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Summary

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CHAPTER 356: SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

OVERVIEW & EPIDEMIOLOGY

• Systemic Lupus Erythematosus (SLE) is an autoimmune disease where damage to organs is mediated by autoantibodies and immune complex deposits.
• SLE is 5-6 times more common in females than males, with 90% of patients being females of child-bearing age.
• The prevalence of SLE is highest in African-American and Afro-Caribbean women and lowest in white men.
• In most SLE patients, autoantibodies are present for a few years before the first clinical symptom appears.
• The disease course of SLE for ~85% of patients involves active disease or flares annually, with less than 5% achieving permanent complete remission.

SLE: PATHOGENESIS, ETIOLOGY, AND CLINICAL FINDINGS

SLE: CLINICAL MANIFESTATIONS

SLE: DIAGNOSIS AND TREATMENT

CHAPTER 357: ANTIPHOSPHOLIPID SYNDROME (APS)

OVERVIEW, PATHOGENESIS, AND CLINICAL FINDINGS

CHAPTER 365: INFLAMMATORY MYOPATHIES

OVERVIEW AND DIAGNOSIS

• Inflammatory myopathies are a group of diseases characterized by progressive and symmetric proximal muscle weakness, which is initially painful. Sensory function is preserved.
• Five Types: Dermatomyositis (DM), Polymyositis (PM), Immune-mediated necrotizing myopathy (IMNM), Antisynthetase syndrome (AS), and Inclusion body myositis (IBM).
• Diagnostic Modalities:
  • Serum Creatine Kinase (CK): The most sensitive lab marker of muscle destruction.
  • EMG/NCS: Helps localize the lesion to the muscle and guides biopsy.
  • Myositis-Specific Antibodies (MSAs): Help distinguish between the different subtypes.
  • Muscle MRI: Assesses the extent of muscle involvement and guides biopsy.
  • Muscle Biopsy: The definitive diagnostic modality.

TYPES OF INFLAMMATORY MYOPATHIES

TREATMENT OF INFLAMMATORY MYOPATHIES

• First-line: Steroids are the standard treatment for inflammatory myopathies.
• Second-line: Steroid-sparing agents like Methotrexate (preferred), Azathioprine, or Mycophenolate (preferred for ILD) are used for severe disease or to taper steroids.
• Refractory Disease: IV Immunoglobulin (IVIG) or Rituximab may be used.
• IMNM: Requires steroids plus a second-line agent from the start.
• IBM: Often does not respond to immunosuppressive therapy; the main therapy is Physical and Occupational Therapy (PT/OT).
• Monitoring: Treatment adjustments should be based on objective improvement in muscle strength, not just on CK levels.
• Steroid Myopathy: If weakness develops on high-dose steroids with a normal CK level, it may be steroid-induced myopathy rather than a disease relapse.

CHAPTER 361: SJÖGREN'S SYNDROME

HIGH-YIELD COMPARISONS & DIFFERENTIATORS

1. SLE Arthritis vs. RA Arthritis: Both can present in young women with symmetric polyarthritis of the hands. However, SLE arthritis is rarely erosive, while RA is classically erosive and deforming.
2. SLE Mucosal Ulcers: Oral ulcers are painless and do NOT correlate with disease activity, whereas Nasal ulcers (on the lower septum) ARE associated with disease activity.
3. SLE-Specific Antibodies: Anti-dsDNA is specific for SLE and its levels often correlate with disease activity (especially nephritis). Anti-Sm is also highly specific for SLE but its levels do not correlate with disease activity.
4. SLE Cutaneous Rashes:
   • Malar Rash (Acute): Erythematous rash on cheeks, spares nasolabial folds, non-scarring.
   • Subacute Cutaneous Lupus (SCLE): Photosensitive annular or psoriasiform rashes, spares the face, non-scarring, associated with anti-Ro.
   • Discoid Lupus (DLE) (Chronic): Circular, atrophic, hyperpigmented lesions that cause scarring and disfigurement.
5. Polymyositis vs. Dermatomyositis: The key differentiator is the rash. DM has pathognomonic rashes (Heliotrope, Gottron's) and is highly associated with malignancy. PM has no rash. Histologically, PM has endomysial infiltrates, while DM has perimysial infiltrates and perifascicular atrophy.
6. Polymyositis vs. Inclusion Body Myositis (IBM): Both show endomysial inflammation on biopsy. However, IBM occurs in older men (>50), causes asymmetric and distal weakness (finger flexors), has rimmed vacuoles on biopsy, is associated with the anti-cN-1A antibody, and responds poorly to treatment.
7. Dermatomyositis vs. Antisynthetase Syndrome (AS): AS is a subtype of DM. Differentiators for AS are the triad of myositis, ILD, and non-erosive arthritis, plus the presence of mechanic's hands and anti-synthetase antibodies (e.g., anti-Jo-1). Importantly, AS does not carry the increased malignancy risk seen in classic DM.
8. SLE vs. Sjögren's Syndrome: Both are autoimmune, affect women, and can have positive anti-Ro/La. SLE is a systemic disease with prominent features like nephritis and malar rash. Sjögren's is defined by sicca symptoms (dry eyes/mouth) from exocrine gland destruction and carries a significant risk of lymphoma.
9. SLE Hematologic Findings: SLE is unique among many connective tissue diseases for causing leukopenia, lymphopenia, and thrombocytopenia. Other inflammatory conditions often cause leukocytosis.
10. Lupus Nephritis Induction Meds: For fertility concerns, Mycophenolate Mofetil (MMF) is preferred over Cyclophosphamide, which carries a high risk of permanent ovarian failure.
11. Life-Threatening vs. Non-Life-Threatening SLE: Treatment differs drastically. Non-life-threatening disease (skin, joints) is managed with NSAIDs, Hydroxychloroquine, and low-dose steroids. Life-threatening disease (renal, CNS, cardiac, severe hematologic) requires high-dose glucocorticoids and potent immunosuppressants.
12. Antiphospholipid Antibodies: Lupus Anticoagulant (LA) is the strongest predictor of thrombosis. Anti-β2-Glycoprotein I is the most specific antibody for APS diagnosis (97% specificity). Positive lab tests must be confirmed ≥12 weeks apart to be diagnostically significant.
13. Relapse of Myositis vs. Steroid Myopathy: Both cause weakness. A myositis relapse is typically associated with a rising CK level. Steroid-induced myopathy occurs on high-dose steroids and is characterized by a normal CK level.

QA

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CHAPTER 356: SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

OVERVIEW & EPIDEMIOLOGY

1. How is organ damage mediated in Systemic Lupus Erythematosus (SLE)? | By autoantibodies and immune complex deposits.
2. In SLE, what is the prevalence ratio of females to males? | 5-6 times more common in females.
3. What percentage of SLE patients are females of child-bearing age? | 90%.
4. In which populations is the prevalence of SLE highest and lowest? | Highest: African-American and Afro-Caribbean women.
   Lowest: white men.
5. In most SLE patients, when do autoantibodies appear relative to the first clinical symptom? | For a few years before the first clinical symptom appears.
6. What is the typical disease course for approximately 85% of SLE patients? | Involves active disease or flares annually.
7. What percentage of SLE patients achieve permanent complete remission? | Less than 5%.

SLE: PATHOGENESIS, ETIOLOGY, AND CLINICAL FINDINGS 8. What is the core mechanism of SLE pathogenesis? | Interactions between susceptible genes and environmental factors. 9. What is a key initiating step in SLE pathogenesis involving innate immunity? | Activation of innate immunity (dendritic cells, monocyte/macrophages). 10. What do activated innate immune cells produce in SLE, creating a genetic "signature"? | IFN-alpha. 11. What percentage of known predisposing genes for SLE influence IFN production/function? | Approximately 50%. 12. What is the most characteristic increased gene expression pattern for SLE? | The pattern related to IFN-alpha. 13. Describe the dysfunction of B and T cells in SLE pathogenesis. | Lowered activation thresholds of B and T cells. 14. What process is reduced in SLE pathogenesis regarding waste clearance? | Reduced clearance of immune complexes and apoptotic cells. 15. SLE is described as what kind of genetic disease? | A multigenetic disease. 16. What gene is associated with End-Stage Renal Disease (ESRD) in all ancestries with SLE? | The MYH9/APOL1 gene. 17. In which ancestry are APOL1G1/G2 variants associated with ESRD? | Only in African Americans. 18. Which spectrum of UV light is a more potent trigger for SLE? | The UV-B spectrum. 19. Which infection is particularly noted to activate autoreactive T and B cells in SLE? | Epstein-Barr Virus (EBV). 20. How can female hormones like estradiol contribute to SLE? | Increasing the activation, survival, and activity of abnormal immune cells. 21. Name four other environmental triggers for SLE. | Tobacco smoking,
prolonged exposure to silica,
air pollution,
pesticides. 22. What is the primary purpose of SLE classification criteria (like SLICC or EULAR/ACR)? | To standardize patient groups in clinical trials. 23. According to SLICC Criteria (2012), how is a patient classified with SLE? | At least 4 criteria, with at least 1 clinical and 1 immunologic criterion. 24. What is the entry criterion for the 2019 EULAR/ACR criteria for SLE? | A positive ANA test (≥1:80). 25. What score is needed to classify a patient as having SLE using the 2019 EULAR/ACR criteria? | A score of 10 or more points.

SLE: CLINICAL MANIFESTATIONS 26. What are common initial systemic symptoms of SLE? (3) | Fatigue, myalgias, and arthralgias. 27. How can severe systemic illness in SLE present? (4) | Fever, weight loss, anemia, and prostration. 28. Describe the SLE Malar Rash. | An erythematous, elevated, pruritic rash that spares the nasolabial folds. 29. What is a key feature of Subacute Cutaneous Lupus (SCLE) lesions? | Scaly red patches (psoriasiform) or circular flat red-rimmed lesions (annular). 30. Which antibody is often associated with Subacute Cutaneous Lupus (SCLE)? | Anti-Ro (SS-A) antibodies. 31. Describe the appearance of Discoid Lupus (DLE) lesions. | Circular, raised, scaly, hyperpigmented rims with depigmented, atrophic centers. 32. What percentage of people with Discoid Lupus (DLE) develop systemic SLE? | Only 5%. 33. Describe the alopecia associated with SLE. | Non-scarring; hair typically grows back. 34. Which SLE mucosal ulcers are typically painless and NOT associated with disease activity? | Oral ulcers. 35. Which SLE mucosal ulcers ARE associated with disease activity? | Nasal ulcers (on the lower nasal septum). 36. How does SLE arthritis differ from Rheumatoid Arthritis? | It is RARELY the erosive type. 37. What musculoskeletal manifestation can SLE cause besides arthritis? | Proximal muscle myositis. 38. What is the most serious manifestation of SLE and a leading cause of mortality? | Lupus Nephritis (LN). 39. What is crucial for the diagnosis and for guiding therapy in Lupus Nephritis? | A renal biopsy. 40. Which classes of Lupus Nephritis require aggressive treatment? (3) | Classes III, IV, and V. 41. Enumerate the 6 classes of Lupus Nephritis. | Class I: Minimal Mesangial LN
Class II: Mesangial Proliferative LN
Class III: Focal LN
Class IV: Diffuse LN
Class V: Membranous LN
Class VI: Advanced Sclerosis LN. 42. How can CNS Lupus present? (2 ways) | A diffuse process (headache, psychosis) or a vascular occlusive disease (stroke, TIA). 43. What must be ruled out when considering CNS Lupus-related psychosis? | Steroid-induced psychosis. 44. What is the most common pulmonary manifestation of SLE? | Pleuritis, with or without pleural effusion. 45. Name three other serious pulmonary manifestations of SLE. | Lupus Pneumonitis,
Interstitial Lung Disease (ILD),
shrinking lung syndrome. 46. What is the most frequent cardiac manifestation of SLE? | Pericarditis. 47. What specific valvular heart disease is associated with SLE? | Libman-Sacks vegetations (on mitral/aortic valves). 48. What is the most frequent hematologic manifestation of SLE? | Anemia, typically normochromic normocytic anemia of chronic illness. 49. What type of anemia is also a key feature of SLE? | Hemolytic anemia. 50. What three hematologic findings distinguish SLE from other connective tissue diseases? | Leukopenia, lymphopenia, and thrombocytopenia. 51. What are common GI symptoms in SLE? (3) | Nausea, vomiting, and diarrhea. 52. In active SLE, what may be elevated, requiring exclusion of primary liver problems? | Liver enzymes. 53. What are common ocular manifestations in SLE? (2) | Sicca syndrome (Sjögren's) and nonspecific conjunctivitis. 54. Name two serious, vision-threatening ocular manifestations of SLE. | Retinal vasculitis and optic neuritis.

SLE: DIAGNOSIS AND TREATMENT 55. What is the most important screening test for SLE? | Antinuclear Antibody (ANA) Test. 56. What are the two highly specific antibodies for SLE? | Anti-dsDNA and Anti-Sm. 57. Which SLE-specific antibody's levels often correlate with disease activity? | Anti-dsDNA. 58. The presence of Antiphospholipid (APS) Antibodies in SLE increases the risk for what? (2) | Thrombosis and fetal loss. 59. What happens to Complement C3 and C4 levels in active SLE? | Levels are often low. 60. What are two essential standard screening tests for SLE? | Complete blood count (CBC) and urinalysis. 61. What medication should all lupus patients take for non-life-threatening disease? | Hydroxychloroquine. 62. Name three other standard treatments for non-life-threatening SLE. | Low-dose or topical steroids, NSAIDs, sunscreen (SPF 30). 63. What is the mainstay of treatment for life-threatening SLE? | High-dose glucocorticoids. 64. For Lupus Nephritis induction therapy, which immunosuppressant is preferred for fertility preservation? | Mycophenolate Mofetil (MMF). 65. What is required after induction therapy for Lupus Nephritis to prevent flares? | Lifelong maintenance therapy (Azathioprine or Mycophenolate). 66. Name two biologics that may be used for severe or refractory SLE. | Rituximab or Belimumab or Anifrolumab. 67. Are fertility rates in SLE patients normal? | Yes, fertility rates are normal. 68. The rate of fetal loss is increased in SLE, especially with what three conditions? | High disease activity, active nephritis, or positive antiphospholipid antibodies. 69. For a better pregnancy outcome, SLE patients should be in remission for how long prior to conception? | At least 6 months. 70. Why must ALL pregnant women with SLE be tested for anti-Ro antibodies? | High risk for congenital heart block in the fetus. 71. Which three medications are teratogenic and must be stopped before conception in SLE patients? | Methotrexate, Mycophenolate, and Cyclophosphamide.

CHAPTER 357: ANTIPHOSPHOLIPID SYNDROME (APS)

72. What is Antiphospholipid Syndrome (APS)? | An autoantibody-mediated acquired thrombophilia.
73. What is Catastrophic APS (CAPS)? | A rapidly progressive thromboembolic disease involving three or more organs.
74. What percentage of SLE patients have positive antiphospholipid antibodies? | About 30-40%.
75. What is the proposed theory for the pathogenesis of Antiphospholipid Syndrome? | A "two-hit" theory.
76. What is the purpose of the Lupus Anticoagulant (LA) test? | A functional test that detects antibodies prolonging coagulation tests.
77. What is the most specific antibody for Antiphospholipid Syndrome (APS)? | Anti-β2-Glycoprotein I (Anti-β2GPI) antibodies (97% specificity).
78. When should Antiphospholipid Syndrome (APS) be strongly suspected? | In patients <55 years with unprovoked thrombosis, stroke, or pregnancy morbidity.
79. What does the Revised Sapporo Criteria for APS require for diagnosis? | ≥1 clinical criterion AND ≥1 laboratory criterion confirmed ≥12 weeks apart.
80. According to the ACR/EULAR 2023 criteria, how is a patient classified with APS? | Score ≥3 points in clinical domain and ≥3 points in laboratory domain.
81. How is a high-risk profile defined in Antiphospholipid Syndrome? (3) | Presence of LA, double/triple antibody positivity, or persistently high titers.
82. How is asymptomatic high-risk Antiphospholipid Syndrome treated? | Low-dose aspirin (LDA) 75-100 mg/day.
83. How is Obstetric APS (history of pregnancy loss only) treated during pregnancy? | LDA + prophylactic heparin.
84. What is the treatment for Thrombotic APS (history of thrombosis)? | Lifelong anticoagulation with a Vitamin K Antagonist (Warfarin).

CHAPTER 365: INFLAMMATORY MYOPATHIES

85. What characterizes Inflammatory Myopathies? | Progressive and symmetric proximal muscle weakness, initially painful.
86. Name the five types of Inflammatory Myopathies. | Dermatomyositis (DM), Polymyositis (PM), IMNM, Antisynthetase syndrome (AS), and Inclusion body myositis (IBM).
87. What is the most sensitive lab marker of muscle destruction in Inflammatory Myopathies? | Serum Creatine Kinase (CK).
88. What is the definitive diagnostic modality for Inflammatory Myopathies? | Muscle Biopsy.
89. How does Polymyositis (PM) present? | Symmetric proximal muscle weakness with NO RASH.
90. What does histopathology show in Polymyositis (PM)? | Inflammatory cell infiltrates in the endomysium.
91. How does Dermatomyositis (DM) present? | As polymyositis WITH A RASH.
92. Dermatomyositis (DM) is highly associated with what condition? | Malignancy (15% risk within 3 years).
93. Name two pathognomonic rashes of Dermatomyositis (DM). | Heliotrope rash and Gottron's sign/papules.
94. Which two MSAs in Dermatomyositis (DM) are associated with increased cancer risk? | Anti-TIF1 & Anti-NXP2.
95. What does histopathology show in Dermatomyositis (DM)? | Perimysial/perivascular infiltrates and perifascicular atrophy.
96. Antisynthetase Syndrome is characterized by what specific finding on the hands? | Mechanic's hands.
97. Does Antisynthetase Syndrome (AS) increase the risk for malignancy? | No.
98. What is the most common antibody in Antisynthetase Syndrome (AS)? | Anti-Jo-1.
99. What antibody is associated with statin-induced Immune-Mediated Necrotizing Myopathy (IMNM)? | Anti-HMGCR.
100. What does histopathology show in Immune-Mediated Necrotizing Myopathy (IMNM)? | Necrotic fibers with a paucity of inflammatory cells.
101. What is the most common myopathy in individuals aged >50? | Inclusion Body Myositis (IBM).
102. How does the muscle weakness present in Inclusion Body Myositis (IBM)? | Slowly progressive, asymmetric, may start distally.
103. What is a highly specific diagnostic marker for Inclusion Body Myositis (IBM)? | Anti-cN-1A antibody.
104. What distinguishes Inclusion Body Myositis (IBM) histopathology from Polymyositis? | Presence of rimmed vacuoles and amyloid deposits.
105. What is the first-line treatment for Inflammatory Myopathies? | Steroids.
106. Which second-line agent is preferred for Inflammatory Myopathies with ILD? | Mycophenolate.
107. Which Inflammatory Myopathy requires steroids plus a second-line agent from the start? | Immune-Mediated Necrotizing Myopathy (IMNM).
108. What is the main therapy for Inclusion Body Myositis (IBM)? | Physical and Occupational Therapy (PT/OT).
109. How should treatment adjustments be monitored for Inflammatory Myopathies? | Based on objective improvement in muscle strength, not just CK levels.
110. How can steroid-induced myopathy be differentiated from a disease relapse? | Steroid myopathy occurs with a normal CK level.

CHAPTER 361: SJÖGREN'S SYNDROME

111. What is Sjögren's Syndrome characterized by? | Lymphocyte infiltration of exocrine glands and B-cell hyperactivity.
112. What are the two key autoantibodies in Sjögren's Syndrome? | Anti-Ro/SS-A and Anti-La/SS-B.
113. What are the hallmark glandular symptoms of Sjögren's Syndrome? | Sicca symptoms: Dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia).
114. Patients with Sjögren's Syndrome have an increased risk of developing what malignancy? | Lymphoma.
115. What are the two definitive tests for diagnosing Sjögren's Syndrome? | Positive serology (Anti-Ro/SS-A or Anti-La/SS-B) or a minor salivary gland biopsy.
116. Name two secretagogue medications used to treat Sjögren's Syndrome. | Pilocarpine or Cevimeline.
117. What medication is used for arthralgias in Sjögren's Syndrome? | Hydroxychloroquine.
118. What classes of medications should be avoided in Sjögren's Syndrome as they can worsen dryness? | Diuretics, anticholinergics, and some antidepressants.

HIGH-YIELD COMPARISONS & DIFFERENTIATORS

119. How does SLE arthritis differ from RA arthritis regarding erosions? | SLE arthritis is rarely erosive.
120. In SLE, which mucosal ulcers ARE associated with disease activity? | Nasal ulcers.
121. Compare Anti-dsDNA and Anti-Sm antibodies in SLE regarding disease activity correlation. | Anti-dsDNA levels correlate with activity; Anti-Sm levels do not.
122. Differentiate Malar rash, SCLE, and DLE in SLE based on scarring. | Malar and SCLE are non-scarring; DLE causes scarring.
123. What is the key differentiator between Polymyositis and Dermatomyositis? | The rash in Dermatomyositis.
124. Compare the muscle weakness pattern in Polymyositis vs. Inclusion Body Myositis. | PM: symmetric/proximal.
     IBM: asymmetric/distal.
125. How does Antisynthetase Syndrome (AS) differ from classic Dermatomyositis (DM) regarding malignancy risk? | AS does not carry the increased malignancy risk.
126. What is the defining feature of Sjögren's Syndrome compared to SLE? | Sicca symptoms (dry eyes/mouth).
127. What hematologic finding is characteristic of SLE compared to other inflammatory conditions? | Leukopenia, lymphopenia, and thrombocytopenia.
128. For lupus nephritis induction, which drug is preferred to preserve fertility instead of Cyclophosphamide? | Mycophenolate Mofetil (MMF).
129. How does treatment differ for life-threatening vs. non-life-threatening SLE? | Life-threatening requires high-dose glucocorticoids and immunosuppressants.
130. In Antiphospholipid Syndrome, which antibody is the most specific for diagnosis? | Anti-β2-Glycoprotein I.
131. How is a myositis relapse differentiated from steroid myopathy? | Myositis relapse has a rising CK level; steroid myopathy has a normal CK.

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Summary

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CHAPTER 363: THE VASCULITIS SYNDROMES

I. GENERAL PRINCIPLES

• Definition of Vasculitis: Vasculitis is characterized by inflammation of blood vessels, which compromises the vessel lumen and leads to ischemia of the tissues it supplies.
• Primary vs. Secondary Vasculitis: Primary vasculitis is when vasculitis is the sole disease manifestation. Secondary vasculitis occurs as part of another underlying disease (e.g., Hepatitis C, HIV).
• Constitutional Signs/Symptoms of Vasculitis: Common features of inflammation include fever, elevated ESR/CRP, anemia (of chronic disease or from bleeding), leukocytosis, and thrombocytosis.
• Diagnosis of Vasculitis: A tissue biopsy provides the definitive diagnosis. An arteriogram is used for medium- to large-vessel vasculitis if a biopsy cannot be done. It is crucial to rule out other diseases that can mimic vasculitis.
• General Signs/Symptoms Suggestive of Vasculitis: Systemic symptoms (malaise, fever, weight loss), respiratory symptoms (cough, hemoptysis), skin changes (purpura, ulcers), ENT issues (epistaxis, sinusitis), GI pain, and neurologic deficits are common but vague.

II. PATHOPHYSIOLOGY

• Immune-Mediated Pathogenesis: Most vasculitides are immune-mediated, resulting from a complex interaction between genetic predisposition, environmental exposures, and immune regulatory mechanisms.
• Three Main Pathophysiologic Mechanisms:
  1. Pathogenic Immune-Complex Formation: Antigen-antibody complexes (e.g., in Hepatitis B-associated PAN, Hepatitis C-associated cryoglobulinemia) deposit in vessel walls, activating complement and causing neutrophil-mediated damage.
  2. Antineutrophil Cytoplasmic Antibodies (ANCA) Production: Autoantibodies target neutrophil proteins (PR3, MPO), causing neutrophil activation and endothelial injury, leading to small-vessel vasculitis.
  3. Pathogenic T-Lymphocyte Responses & Granuloma Formation: T-cells are activated and, along with macrophages, infiltrate the vessel wall, leading to inflammation and granuloma formation.

III. ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCA)

• ANCA Definition: ANCAs are autoantibodies directed against proteins in the cytoplasmic granules of neutrophils and monocytes.
• Cytoplasmic ANCA (cANCA): cANCA is directed against serine proteinase (PR3) and is highly associated with Granulomatosis with Polyangiitis (GPA).
• Perinuclear ANCA (pANCA): pANCA is directed against myeloperoxidase (MPO) and is associated with Microscopic Polyangiitis (MPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA).
• Non-MPO/PR3 ANCA: Other antigens can cause ANCA positivity (e.g., in RA, SLE, certain drugs), but these are considered false-positives for ANCA-associated vasculitis and do not cause vasculitis. Positive tests must be confirmed for PR3 or MPO specificity.
• Clinical Usefulness of ANCA: ANCAs are not part of the diagnostic criteria but have high diagnostic potential. Titers do not always correlate with disease activity, so treatment decisions are based on clinical findings.

IV. VASCULITIS CLASSIFICATION BY VESSEL SIZE & CLINICAL CLUES

SMALL VESSEL VASCULITIS

A. GRANULOMATOSIS WITH POLYANGIITIS (GPA / WEGENER'S)

• Hallmarks: GPA is a granulomatous vasculitis of the upper and lower respiratory tracts combined with glomerulonephritis.
• Pathology: The key feature is necrotizing granulomatous inflammation of small arteries and veins. Chronic nasal carriage of S. aureus is associated with higher relapse rates.
• Clinical - Upper Respiratory Tract (95%): Sinus pain, purulent/bloody nasal discharge, nasal septal perforation leading to saddle nose deformity, and subglottic tracheal stenosis are characteristic.
• Clinical - Lung (85-90%): Manifestations range from asymptomatic infiltrates to cough and hemoptysis. Chest imaging often shows multiple, bilateral, nodular cavitary infiltrates.
• Clinical - Kidney (77%): Rapidly progressive, crescentic glomerulonephritis is common.
• Clinical - Other: Eye involvement (retroorbital mass, scleritis), skin lesions (palpable purpura), and an increased incidence of venous thrombosis can occur.
• Diagnosis: The definitive diagnosis is made by tissue biopsy demonstrating necrotizing granulomatous vasculitis. Pulmonary tissue provides the highest diagnostic yield.
• Lab Findings: Anti-PR3 ANCA (cANCA) is highly specific for GPA (~90% of active cases). Elevated ESR/CRP and thrombocytosis are also seen.
• Treatment (Severe Disease): Induction therapy involves high-dose glucocorticoids plus either Rituximab or Cyclophosphamide. This is followed by maintenance therapy with agents like Rituximab, Azathioprine, or Methotrexate.

B. MICROSCOPIC POLYANGIITIS (MPA)

• Hallmarks: MPA is a necrotizing pauci-immune vasculitis of small vessels (capillaries, venules) that lacks granulomatous inflammation.
• Key Differentiator from GPA: The primary distinction from GPA is the absence of granulomas and the absence of significant upper airway disease.
• Clinical Manifestations: Glomerulonephritis and pulmonary hemorrhage are very common.
• Diagnosis & Treatment: Diagnosis is confirmed by biopsy showing non-granulomatous, pauci-immune vasculitis. Treatment is the same as for severe GPA.

C. EOSINOPHILIC GRANULOMATOSIS WITH POLYANGIITIS (EGPA / CHURG-STRAUSS)

• Hallmarks: EGPA is characterized by asthma, peripheral and tissue eosinophilia, and extravascular granuloma formation.
• Pathology: Histology shows granulomatous inflammation with prominent eosinophilic infiltration of tissues. The classic triad is Asthma + Eosinophilia + Necrotizing Granulomatous Vasculitis.
• Clinical Manifestations: Pulmonary findings dominate, especially severe asthmatic attacks. Allergic rhinitis is common. Mononeuritis multiplex is the second most common manifestation. Cardiac involvement is a major cause of mortality. Kidney involvement is less common and less severe than in GPA or MPA.
• Lab Findings: The hallmark is marked eosinophilia (>1000 cells/µL). p-ANCA (anti-MPO) is present in about half of patients.
• Diagnosis & Treatment: Diagnosis is based on clinical features (asthma, eosinophilia) and confirmed by biopsy. First-line treatment is systemic glucocorticoids. For severe disease, Cyclophosphamide is used. Mepolizumab (anti-IL-5) is effective for relapsing disease.

D. IgA VASCULITIS (HENOCH-SCHÖNLEIN PURPURA / HSP)

• Hallmarks: Often triggered by an upper respiratory tract infection, IgA vasculitis typically affects children.
• Pathology: Caused by the deposition of IgA-containing immune complexes in small vessels.
• Clinical Triad: The classic presentation includes 1) Palpable purpura on dependent areas (legs, buttocks), 2) Abdominal pain, and 3) Polyarthralgia.
• Renal Involvement: Glomerulonephritis can occur and is the main determinant of long-term prognosis, especially in adults.
• Diagnosis: Diagnosis is clinical, based on the classic triad. A biopsy of the skin or kidney will show IgA and C3 deposition. Platelet count and complement levels are typically normal.
• Treatment: Mostly supportive. Glucocorticoids are used to relieve severe abdominal and joint pain but do not prevent renal disease. Immunosuppressants are used for severe renal disease.

E. IDIOPATHIC CUTANEOUS VASCULITIS

• Hallmarks: Also known as hypersensitivity vasculitis or cutaneous leukocytoclastic angiitis, this is inflammation confined to the blood vessels of the dermis, with no systemic organ involvement.
• Pathology: A leukocytoclastic vasculitis (nuclear debris from neutrophils) primarily affecting postcapillary venules.
• Clinical Manifestations: Presents only with skin lesions, most commonly palpable purpura, but can also be urticaria, vesicles, or ulcers.
• Diagnosis & Treatment: Diagnosis is by skin biopsy. Treatment involves identifying and removing the inciting agent (e.g., drug, infection). Idiopathic cases may resolve spontaneously or require steroids.

MEDIUM VESSEL VASCULITIS

A. POLYARTERITIS NODOSA (PAN)

• Hallmarks: PAN is a necrotizing vasculitis of small and medium-sized arteries, sparing venules. It does not involve pulmonary arteries and is not associated with ANCA.
• Associations: About 30% of cases were historically associated with Hepatitis B infection. It can also be linked to Hepatitis C.
• Pathology: A key feature is the formation of aneurysmal dilations along the arteries, which can be seen on arteriogram ("beads on a string" or "rosary sign"). Histology shows necrotizing inflammation without granulomas.
• Clinical Manifestations: Symptoms depend on the organs affected (renal, visceral arteries). Renal involvement causes renovascular hypertension due to glomerulosclerosis, not glomerulonephritis. Patients may present with abdominal pain, skin nodules, or mononeuritis multiplex.
• Diagnosis: The gold standard is a biopsy of an affected organ (skin, nerve, muscle). An arteriogram showing aneurysms and stenosis in renal, hepatic, or visceral vessels is also diagnostic.
• Treatment: High-dose glucocorticoids. Cyclophosphamide is added for severe, refractory disease.

LARGE VESSEL VASCULITIS

A. GIANT CELL ARTERITIS (GCA) & POLYMYALGIA RHEUMATICA (PMR)

• Hallmarks: GCA is a vasculitis of large and medium vessels, typically the carotid artery and its branches (especially the temporal artery). It almost exclusively affects individuals > 50 years old.
• Polymyalgia Rheumatica (PMR): A related syndrome causing stiffness, aching, and pain in the muscles of the neck, shoulders, and hips. Occurs in ~50% of GCA patients.
• Pathology: Histology shows mononuclear cell infiltrates within the vessel wall with giant cell formation.
• Clinical Manifestations: The predominant symptom is a new-onset headache. The temporal artery may be tender, thickened, or nodular. Jaw claudication is highly specific. The most dreaded complication is ischemic optic neuropathy, which can cause sudden blindness.
• Diagnosis: The gold standard for GCA is a biopsy of the temporal artery. For isolated PMR, diagnosis is clinical (age >50, typical symptoms, elevated ESR/CRP, and prompt response to low-dose steroids).
• Treatment: GCA is a medical emergency requiring immediate high-dose glucocorticoids to prevent blindness. Tocilizumab (anti-IL-6) is used for refractory disease. PMR is treated with low-dose steroids.

B. TAKAYASU’S ARTERITIS

• Hallmarks: TA is an inflammatory and stenotic disease of the aorta and its main branches, affecting young women (typically < 50 years old). It is also known as "pulseless disease."
• Pathology: It is a panarteritis with a strong predilection for the aortic arch and its branches, with the subclavian artery being most commonly involved.
• Clinical Manifestations: Early systemic symptoms include fever, malaise, and weight loss. Later vascular symptoms include arm claudication, blood pressure discrepancies between arms, absent or weak peripheral pulses, and arterial bruits.
• Diagnosis: Diagnosis is suspected in a young woman with characteristic vascular signs and confirmed by arteriography (CTA/MRA) showing stenosis, occlusion, or aneurysms of the aorta and its branches.
• Treatment: Glucocorticoids are the mainstay of therapy. Surgical or endovascular procedures may be needed for critical stenosis after inflammation is controlled.

CHAPTER 359: ACUTE RHEUMATIC FEVER (ARF)

I. GENERAL PRINCIPLES

• Definition: ARF is a multi-system, nonsuppurative inflammatory disease that is an immune-mediated sequela of a Group A Streptococcus (GAS) pharyngitis. It is not an active infection.
• Epidemiology: ARF is a disease of poverty, mainly affecting children aged 5-15 years.
• Etiology: Caused by a throat infection with certain rheumatogenic M protein strains of S. pyogenes (Group A Strep).
• Pathogenesis: The mechanism is molecular mimicry, where antibodies and T-cells directed against streptococcal antigens cross-react with human tissues (heart, joints, CNS).
• Latency Period: There is a latent period of ~3 weeks between the GAS pharyngitis and the onset of ARF symptoms. Chorea may have a much longer latency period (up to 6 months).

II. CLINICAL FEATURES & DIAGNOSIS (REVISED JONES CRITERIA)

• Diagnosis: Requires evidence of a preceding GAS infection (e.g., positive throat swab, rapid antigen test, or elevated ASO/anti-DNase B titers) plus a combination of major and minor criteria.
• Echocardiography: Recommended in all suspected cases to detect valvular regurgitation and identify subclinical carditis.

• Carditis (50-75%): The most serious manifestation, potentially causing permanent damage (Rheumatic Heart Disease). It is a pancarditis. The mitral valve is almost always affected, leading to regurgitation.
• Polyarthritis (60–75%): A migratory arthritis affecting large joints (knees, ankles). It is typically very painful but shows a dramatic response to salicylates. If joint pain persists >2 days after starting NSAIDs, ARF is unlikely.
• Sydenham Chorea: A delayed neurologic manifestation with involuntary, purposeless movements, often associated with emotional lability. More common in females.
• Erythema Marginatum (<5%): A pink, macular rash with serpiginous, spreading edges, typically on the trunk and limbs. It is evanescent (comes and goes).
• Subcutaneous Nodules (<5%): Painless, mobile lumps over bony prominences. Associated with severe carditis.

III. TREATMENT & PROPHYLAXIS

• Acute Management:
  1. Eradicate GAS: A single dose of intramuscular Benzathine Penicillin G or a 10-day course of oral penicillin. This is given even if the throat swab is negative.
  2. Anti-inflammatory Therapy:
     • Aspirin/NSAIDs for arthritis and fever.
     • Corticosteroids are reserved for patients with severe carditis (heart failure).
  3. Supportive Care: Bed rest is advised during active carditis.
• Secondary Prophylaxis: The cornerstone of preventing RHD is long-term antibiotic prophylaxis to prevent recurrent GAS infections. Intramuscular Benzathine Penicillin G every 3-4 weeks is the preferred regimen.
• Duration of Secondary Prophylaxis:
  • ARF without Carditis: 5 years or until age 21 (whichever is longer).
  • ARF with Carditis but NO residual heart disease: 10 years or until age 21 (whichever is longer).
  • ARF with Carditis AND residual heart disease: 10 years or until age 40 (whichever is longer), and potentially lifelong for severe valvular disease.
• Complications: The primary long-term complication is Rheumatic Heart Disease (RHD), leading to chronic valvular stenosis or regurgitation, heart failure, and arrhythmias.

HIGH-YIELD COMPARISONS

• GPA vs. MPA: GPA has granulomas and significant upper respiratory tract involvement (sinusitis, saddle nose); MPA lacks both of these features. GPA is typically c-ANCA (PR3) positive, while MPA is p-ANCA (MPO) positive.
• ANCA Vasculitides vs. PAN: ANCA-associated vasculitides (GPA, MPA, EGPA) are ANCA-positive. Polyarteritis Nodosa (PAN) is ANCA-negative. PAN affects arteries only, while MPA can affect venules.
• EGPA vs. Other AAVs: EGPA (Churg-Strauss) is distinguished by the presence of asthma and profound peripheral eosinophilia, which are absent in GPA and MPA.
• Giant Cell Arteritis vs. Takayasu's Arteritis: Both are large-vessel vasculitides, but GCA affects patients >50 years old, while Takayasu's affects patients <50 years old (typically young women).
• PAN vs. IgA Vasculitis: PAN is a necrotizing arteritis of medium vessels without significant immune deposits, often presenting with visceral ischemia. IgA vasculitis is a small-vessel vasculitis caused by IgA deposition, classically presenting with palpable purpura, arthralgia, and abdominal pain.
• ARF Arthritis vs. Rheumatoid Arthritis: ARF arthritis is migratory, moving from joint to joint, and has a dramatic, rapid response to salicylates. RA is typically a symmetric, persistent, and erosive arthritis.
• GPA Pulmonary Nodules vs. Other Causes: The lung nodules in GPA are characteristically cavitary.
• Vasculitic Glomerulonephritis vs. PAN Renal Disease: ANCA vasculitides and IgA vasculitis cause an active, inflammatory glomerulonephritis (GN) with an active urine sediment. PAN causes renal artery stenosis and ischemia, leading to renovascular hypertension and glomerulosclerosis, not typically a true GN.
• c-ANCA vs. p-ANCA: c-ANCA targets PR3 and is highly specific for GPA. p-ANCA targets MPO and is most commonly seen in MPA and EGPA.
• Diagnosis: Biopsy vs. Arteriogram: Biopsy is the gold standard for definitive diagnosis in most vasculitides (especially small-vessel). An arteriogram (CTA/MRA) is the diagnostic modality of choice for large-vessel vasculitides (Takayasu's) and can be diagnostic in PAN by showing characteristic aneurysms.
• GPA, MPA, EGPA Histology: GPA shows necrotizing granulomas. MPA shows necrotizing vasculitis with no granulomas. EGPA shows necrotizing vasculitis with eosinophil-rich granulomas.
• Treatment: Rituximab vs. Cyclophosphamide: Both are used for induction in severe ANCA-associated vasculitis. Rituximab is often preferred to preserve fertility compared to Cyclophosphamide.
• ARF Primary vs. Secondary Prophylaxis: Primary prophylaxis is treating an acute GAS pharyngitis to prevent a first episode of ARF. Secondary prophylaxis is long-term antibiotic use in a patient who has already had ARF to prevent recurrences and the development of RHD.

QA

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CHAPTER 363: THE VASCULITIS SYNDROMES

I. GENERAL PRINCIPLES

1. What is the fundamental process in Vasculitis? | Inflammation of blood vessels.
2. What are the two main consequences of vasculitis-induced inflammation? | Compromised lumen, tissue ischemia.
3. What defines Primary Vasculitis? | Sole disease manifestation.
4. What defines Secondary Vasculitis? | Occurs with another underlying disease (e.g., Hepatitis C, HIV).
5. What are the common constitutional features of inflammation in Vasculitis? (5) | 1. Fever
   2. Elevated ESR/CRP
   3. Anemia
   4. Leukocytosis
   5. Thrombocytosis
6. What provides the definitive diagnosis for most Vasculitis? | Tissue biopsy.
7. What diagnostic tool is used for medium- to large-vessel vasculitis if a biopsy is not possible? | Arteriogram.
8. What are some general systemic symptoms suggestive of Vasculitis? | Malaise, fever, weight loss.
9. What are other vague signs and symptoms suggestive of Vasculitis? | Respiratory, skin, ENT, GI, neurologic deficits.

II. PATHOPHYSIOLOGY

10. How are most vasculitides mediated? | Immune-mediated.
11. The pathogenesis of vasculitis results from a complex interaction between what three factors? | 1. Genetic predisposition
    2. Environmental exposures
    3. Immune regulatory mechanisms
12. What are the three main pathophysiologic mechanisms of Vasculitis? | 1. Immune-Complex Formation
    2. ANCA Production
    3. T-Lymphocyte Responses & Granuloma Formation
13. Describe the mechanism of Pathogenic Immune-Complex Formation in vasculitis. | Antigen-antibody complexes deposit in vessel walls, activating complement.
14. Describe the mechanism of Antineutrophil Cytoplasmic Antibodies (ANCA) Production in vasculitis. | Autoantibodies cause neutrophil activation and endothelial injury.
15. Describe the mechanism of Pathogenic T-Lymphocyte Responses in vasculitis. | T-cells and macrophages infiltrate the vessel wall, forming granulomas.

III. ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCA)

16. What are ANCAs? | Autoantibodies against proteins in neutrophil and monocyte granules.
17. What is the target of cANCA (cytoplasmic ANCA)? | Serine proteinase (PR3).
18. With which vasculitis is cANCA (anti-PR3) highly associated? | Granulomatosis with Polyangiitis (GPA).
19. What is the target of pANCA (perinuclear ANCA)? | Myeloperoxidase (MPO).
20. With which vasculitides is pANCA (anti-MPO) associated? | Microscopic Polyangiitis (MPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA).
21. What should be suspected if ANCA is positive but not for MPO/PR3 antigens? | False-positive for ANCA-associated vasculitis.
22. Are ANCAs part of the diagnostic criteria for vasculitis? | No.
23. Do ANCA titers always correlate with disease activity? | No, treatment decisions are based on clinical findings.
24. What is the ANCA positivity and predominant type in GPA (Wegener's)? | 80-95%; ~90% cANCA (anti-PR3).
25. What is the ANCA positivity and predominant type in MPA? | ~70%; ~70% pANCA (anti-MPO).
26. What is the ANCA positivity and predominant type in EGPA (Churg-Strauss)? | ~50%; ~40% pANCA (anti-MPO).

IV. VASCULITIS CLASSIFICATION BY VESSEL SIZE & CLINICAL CLUES

27. What are the two main Large Vessel vasculitides? | Giant Cell (Temporal) Arteritis, Takayasu’s Arteritis.
28. What are key clinical clues for Large Vessel vasculitis? | Claudication, asymmetric pulses, blood pressure discrepancies.
29. What are the two main Medium Vessel vasculitides? | Polyarteritis Nodosa (PAN), Kawasaki Disease.
30. What are key clinical clues for Medium Vessel vasculitis? | Livedo reticularis, digital ischemia, mesenteric ischemia.
31. Name the primary types of Small Vessel vasculitis. | ANCA-Associated (GPA, MPA, EGPA), IgA vasculitis, Cryoglobulinemic, Cutaneous.
32. What are key clinical clues for Small Vessel vasculitis? | Palpable purpura, glomerulonephritis, alveolar hemorrhage.

SMALL VESSEL VASCULITIS

A. GRANULOMATOSIS WITH POLYANGIITIS (GPA / WEGENER'S)

33. What are the hallmarks of Granulomatosis with Polyangiitis (GPA)? | Granulomatous vasculitis of upper/lower respiratory tracts + glomerulonephritis.
34. What is the key pathological feature of GPA? | Necrotizing granulomatous inflammation.
35. What is associated with higher relapse rates in GPA? | Chronic nasal carriage of S. aureus.
36. What is a characteristic physical finding from nasal septal perforation in GPA? | Saddle nose deformity.
37. What is a characteristic upper respiratory tract symptom of GPA? | Purulent/bloody nasal discharge.
38. What does chest imaging often show in GPA? | Multiple, bilateral, nodular cavitary infiltrates.
39. What type of kidney disease is common in GPA? | Rapidly progressive, crescentic glomerulonephritis.
40. What is the definitive diagnosis for GPA? | Biopsy showing necrotizing granulomatous vasculitis.
41. Which tissue provides the highest diagnostic yield for GPA? | Pulmonary tissue.
42. Which ANCA is highly specific for GPA? | anti-PR3 ANCA (cANCA).
43. What is the induction therapy for severe GPA? | High-dose glucocorticoids plus Rituximab or Cyclophosphamide.

B. MICROSCOPIC POLYANGIITIS (MPA)

44. What are the hallmarks of Microscopic Polyangiitis (MPA)? | Necrotizing, pauci-immune vasculitis lacking granulomas.
45. What is the primary distinction between MPA and GPA? | Absence of granulomas and significant upper airway disease.
46. What are the two very common clinical manifestations of MPA? | Glomerulonephritis and pulmonary hemorrhage.
47. How is MPA diagnosed and treated? | Diagnosis by biopsy; treatment is same as severe GPA.

C. EOSINOPHILIC GRANULOMATOSIS WITH POLYANGIITIS (EGPA / CHURG-STRAUSS)

48. What are the hallmarks of Eosinophilic Granulomatosis with Polyangiitis (EGPA)? | Asthma, peripheral and tissue eosinophilia, granulomas.
49. What is the classic triad of EGPA? | Asthma + Eosinophilia + Necrotizing Granulomatous Vasculitis.
50. What is the dominant clinical manifestation in EGPA? | Severe asthmatic attacks.
51. What is the second most common manifestation of EGPA? | Mononeuritis multiplex.
52. What lab finding is the hallmark of EGPA? | Marked eosinophilia (>1000 cells/µL).
53. What ANCA is present in about half of EGPA patients? | p-ANCA (anti-MPO).
54. What is first-line treatment for EGPA? | Systemic glucocorticoids.
55. What targeted therapy is effective for relapsing EGPA? | Mepolizumab (anti-IL-5).

D. IgA VASCULITIS (HENOCH-SCHÖNLEIN PURPURA / HSP)

56. What often triggers IgA Vasculitis and who does it typically affect? | Upper respiratory infection; children.
57. What is the pathology of IgA Vasculitis? | Deposition of IgA-containing immune complexes.
58. What is the classic clinical triad of IgA Vasculitis? | 1. Palpable purpura
    2. Abdominal pain
    3. Polyarthralgia
59. What mainly determines long-term prognosis in IgA Vasculitis, especially in adults? | Glomerulonephritis.
60. How is IgA Vasculitis diagnosed? | Clinically, based on the classic triad.
61. What do skin or kidney biopsies show in IgA Vasculitis? | IgA and C3 deposition.

E. IDIOPATHIC CUTANEOUS VASCULITIS

62. What is the hallmark of Idiopathic Cutaneous Vasculitis? | Inflammation confined to dermal blood vessels.
63. What is the pathology of Idiopathic Cutaneous Vasculitis? | Leukocytoclastic vasculitis of postcapillary venules.
64. How does Idiopathic Cutaneous Vasculitis manifest clinically? | Only with skin lesions (e.g., palpable purpura).
65. How is Idiopathic Cutaneous Vasculitis diagnosed and treated? | Diagnosis by skin biopsy; treat by removing inciting agent.

MEDIUM VESSEL VASCULITIS

A. POLYARTERITIS NODOSA (PAN)

66. What are the hallmarks of Polyarteritis Nodosa (PAN)? | Necrotizing vasculitis of small/medium arteries; ANCA-negative.
67. Which infection has been historically associated with PAN? | Hepatitis B.
68. What is a key pathological feature of PAN seen on arteriogram? | Aneurysmal dilations ("beads on a string").
69. What type of renal manifestation does PAN cause? | Renovascular hypertension (not glomerulonephritis).
70. What is the gold standard for diagnosing PAN? | Biopsy of an affected organ.
71. What is the treatment for PAN? | High-dose glucocorticoids.

LARGE VESSEL VASCULITIS

A. GIANT CELL ARTERITIS (GCA) & POLYMYALGIA RHEUMATICA (PMR)

72. What are the hallmarks of Giant Cell Arteritis (GCA)? | Vasculitis of carotid artery branches in individuals > 50 years old.
73. What is Polymyalgia Rheumatica (PMR)? | Syndrome causing stiffness/pain in neck, shoulders, and hips.
74. What does histology show in GCA? | Mononuclear cell infiltrates with giant cell formation.
75. What is the predominant symptom of GCA? | New-onset headache.
76. What is a highly specific symptom for GCA? | Jaw claudication.
77. What is the most dreaded complication of GCA? | Ischemic optic neuropathy (blindness).
78. What is the gold standard for diagnosing GCA? | Biopsy of the temporal artery.
79. How is GCA treated emergently? | Immediate high-dose glucocorticoids.

B. TAKAYASU’S ARTERITIS

80. What are the hallmarks of Takayasu’s Arteritis? | Aortic disease in young women (< 50 years); "pulseless disease".
81. Which part of the aorta and which specific artery are most commonly involved in Takayasu’s Arteritis? | Aortic arch and branches; subclavian artery.
82. What are the later vascular symptoms of Takayasu’s Arteritis? | Arm claudication, BP discrepancies, weak pulses.
83. How is the diagnosis of Takayasu’s Arteritis confirmed? | Arteriography (CTA/MRA).
84. What is the mainstay of therapy for Takayasu’s Arteritis? | Glucocorticoids.

CHAPTER 359: ACUTE RHEUMATIC FEVER (ARF)

I. GENERAL PRINCIPLES

85. What is Acute Rheumatic Fever (ARF) an immune-mediated sequela of? | Group A Streptococcus (GAS) pharyngitis.
86. ARF primarily affects children of what age group? | 5-15 years.
87. What is the pathogenesis of ARF? | Molecular mimicry.
88. What is the typical latent period between GAS pharyngitis and the onset of ARF? | ~3 weeks.
89. Which manifestation of ARF can have a much longer latency period (up to 6 months)? | Chorea.

II. CLINICAL FEATURES & DIAGNOSIS (REVISED JONES CRITERIA)

90. A diagnosis of ARF requires evidence of preceding GAS infection plus what? | A combination of major and minor criteria.
91. Why is echocardiography recommended in all suspected cases of ARF? | To detect subclinical carditis.
92. What are the 5 major manifestations of ARF? (Mnemonic: CANCER) | Carditis
    Arthritis
    Nodules
    Chorea
    ERythema Marginatum
93. What are the 4 minor manifestations of ARF? (Mnemonic: PEF-P) | Polyarthralgia
    Elevated ESR/CRP
    Fever
    PR interval prolongation
94. What is the most serious manifestation of ARF? | Carditis.
95. Which heart valve is almost always affected in rheumatic carditis? | Mitral valve.
96. Describe the arthritis of ARF. | Migratory polyarthritis with dramatic response to salicylates.
97. What is Sydenham Chorea? | Delayed neurologic manifestation with involuntary, purposeless movements.
98. What is Erythema Marginatum? | An evanescent, pink, macular rash with serpiginous edges.
99. What are Subcutaneous Nodules in ARF associated with? | Severe carditis.

III. TREATMENT & PROPHYLAXIS

100. What is the first step in acute management of ARF? | Eradicate GAS (e.g., Benzathine Penicillin G).
101. What anti-inflammatory therapy is used for arthritis in ARF? | Aspirin/NSAIDs.
102. When are corticosteroids used in ARF? | For patients with severe carditis (heart failure).
103. What is the cornerstone of preventing Rheumatic Heart Disease after an episode of ARF? | Secondary prophylaxis (long-term antibiotics).
104. What is the preferred regimen for secondary prophylaxis in ARF? | Intramuscular Benzathine Penicillin G every 3-4 weeks.
105. What is the duration of secondary prophylaxis for ARF without carditis? | 5 years or until age 21 (whichever is longer).
106. What is the duration of secondary prophylaxis for ARF with carditis but NO residual heart disease? | 10 years or until age 21 (whichever is longer).
107. What is the duration of secondary prophylaxis for ARF with carditis AND residual heart disease? | 10 years or until age 40 (whichever is longer), potentially lifelong.
108. What is the primary long-term complication of ARF? | Rheumatic Heart Disease (RHD).

HIGH-YIELD COMPARISONS

109. Compare GPA vs. MPA in terms of pathology and location. | GPA: Granulomas, upper respiratory involvement.
     MPA: No granulomas, no significant upper airway disease.
110. Compare ANCA Vasculitides vs. PAN in terms of ANCA status. | ANCA-associated vasculitides (GPA, MPA, EGPA) are ANCA-positive; Polyarteritis Nodosa (PAN) is ANCA-negative.
111. Compare EGPA vs. Other AAVs based on key features. | EGPA is distinguished by asthma and profound peripheral eosinophilia.
112. Compare Giant Cell Arteritis vs. Takayasu's Arteritis based on patient age. | GCA affects patients >50 years old; Takayasu's affects patients <50 years old.
113. Compare PAN vs. IgA Vasculitis based on vessel size and pathology. | PAN: Medium-vessel necrotizing arteritis.
     IgA Vasculitis: Small-vessel vasculitis from IgA deposition.
114. Compare ARF Arthritis vs. Rheumatoid Arthritis. | ARF arthritis is migratory and responds dramatically to salicylates; RA is symmetric and persistent.
115. Compare pulmonary nodules in GPA vs. other causes. | Lung nodules in GPA are characteristically cavitary.
116. Compare renal disease in Vasculitic Glomerulonephritis vs. PAN. | Vasculitides cause inflammatory GN; PAN causes renovascular hypertension and glomerulosclerosis.
117. Compare c-ANCA vs. p-ANCA based on target and primary disease association. | c-ANCA (anti-PR3) for GPA; p-ANCA (anti-MPO) for MPA and EGPA.
118. Compare the primary diagnostic modality for small vs. large vessel vasculitis: Biopsy vs. Arteriogram. | Biopsy is gold standard for small-vessel; Arteriogram is choice for large-vessel (e.g., Takayasu's).
119. Compare the histology of GPA, MPA, and EGPA. | GPA: Necrotizing granulomas.
     MPA: No granulomas.
     EGPA: Eosinophil-rich granulomas.
120. Compare Rituximab vs. Cyclophosphamide for AAV treatment. | Both are used for induction; Rituximab is often preferred to preserve fertility.
121. Compare ARF Primary vs. Secondary Prophylaxis. | Primary: Prevent first ARF episode.
     Secondary: Prevent recurrence in a patient who has had ARF.

3

Summary

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CHAPTER 360: SYSTEMIC SCLEROSIS (SCLERODERMA) AND RELATED DISORDERS

I. GENERAL PRINCIPLES & DEFINITION

• Systemic Sclerosis (SSc) Definition: Systemic Sclerosis is a multisystem connective tissue disease characterized by chronic inflammation, variable degrees of collagen accumulation (fibrosis), and obliterative vasculopathy affecting the skin and internal organs.
• Pathogenesis Hallmark: The hallmark of Systemic Sclerosis pathogenesis is prominent microangiopathy in multiple vascular beds.
• Key Pathophysiologic Processes in SSc: The pathogenesis of SSc involves three core processes: (1) Diffuse microangiopathy, (2) Inflammation and autoimmunity, and (3) Fibrosis of vascular and visceral tissues.
• Pathogenesis Summary: In SSc, endothelial damage leads to chronic vasoconstriction and luminal narrowing. This stimulates an ongoing immune response (T-cells, B-cells) and the release of growth factors (TGF-β, PDGF), causing fibroblasts to become myofibroblasts. These myofibroblasts produce excessive collagen and extracellular matrix, leading to tissue fibrosis and organ failure.

II. ETIOLOGY & RISK FACTORS

• Etiology of SSc: The cause of SSc is multifactorial, resulting from an interplay of genetic predisposition, epigenetic factors, infectious agents, and environmental exposures.
• Genetic Predisposition in SSc: SSc is associated with HLA class II genes on chromosome 6.
• Infectious Agents Associated with SSc: Potential infectious triggers for SSc include Parvovirus B19, Epstein-Barr virus (EBV), and Cytomegalovirus (CMV).
• Environmental & Drug Exposures in SSc: Occupational exposure to silica (quartz) is a well-documented risk factor. Other associations include gadolinium contrast (nephrogenic fibrosis), polyvinyl chloride, welding fumes, and certain drugs like bleomycin and cocaine.

III. CLASSIFICATION OF SCLERODERMA

• Main Classifications: Scleroderma is broadly classified into Localized Scleroderma and Systemic Sclerosis (SSc).
• Localized Scleroderma: A form of scleroderma that affects only the skin without internal organ involvement.
  • Morphea: A type of localized scleroderma presenting as single or multiple plaques of hardened skin, typically on the trunk.
  • Linear Scleroderma: A type of localized scleroderma presenting as bands of skin thickening on the legs, arms, or face. A facial presentation is termed "en coup de sabre."
• Systemic Sclerosis (SSc): A form of scleroderma involving the skin and internal organs, further divided into limited and diffuse types.
• Limited Cutaneous Systemic Sclerosis (lcSSc):
  • Skin thickening is restricted to areas distal to the elbows and knees, but may also involve the face and neck.
  • Often associated with CREST syndrome manifestations: Calcinosis cutis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia.
  • Note: Limited SSc is not necessarily "mild" scleroderma and can have severe internal organ involvement like Pulmonary Arterial Hypertension (PAH).
• Diffuse Cutaneous Systemic Sclerosis (dcSSc):
  • Characterized by skin thickening that involves proximal limbs (above elbows/knees) and/or the trunk.
  • Associated with a higher risk of early and significant internal organ disease (e.g., ILD, renal crisis) and poorer survival.
• SSc Sine Scleroderma: A rare variant where patients have typical internal organ manifestations and autoantibodies of SSc but lack clinically evident skin thickening.

IV. CLINICAL FEATURES OF SYSTEMIC SCLEROSIS

A. General & Skin Manifestations

• Skin Thickening: The hallmark skin finding is bilateral, symmetric skin thickening and induration, making the skin difficult to pinch.
• "Salt and Pepper" Appearance: A characteristic skin change in SSc involving interspersed areas of hyperpigmentation and hypopigmentation.
• Mauskopf Facie: A "mouse-like" facial appearance due to skin tightening, resulting in a pinched nose, thin lips, prominent teeth, and an expressionless face.
• Sclerodactyly: Thickening and tightening of the skin on the fingers and/or toes.
• Other Skin Findings: Dermal sclerosis can obliterate hair follicles and glands, leading to dryness (xerosis) and itching. Telangiectasias (dilated capillaries) are also common.

B. Vascular Manifestations

• Raynaud's Phenomenon: The most common initial symptom, characterized by episodic vasoconstriction in digits, nose, or earlobes triggered by cold or stress.
• Triphasic Color Change of Raynaud's: The classic sequence is (1) Pallor (white) from vasoconstriction, followed by (2) Cyanosis (blue) from ischemia, and then (3) Hyperemia (red) from reperfusion.
• Complications of Chronic Raynaud's: Chronic, severe Raynaud's can lead to digital pitting scars, ulcers, dissolution (resorption) of distal phalanges, and dystrophic calcification (calcinosis cutis).
• Calcinosis Cutis: The formation of calcium phosphate crystals, often in the soft tissues of the fingers or over bony prominences, associated with chronic disease.

C. Gastrointestinal Manifestations

• GI Involvement: Gut dysmotility is the most common GI issue and can affect any segment of the GI tract, from the mouth to the anus.
• Esophageal Dysfunction: The most frequent GI manifestation, leading to chronic GERD, dysphagia, and risk of Barrett’s esophagus.
• Gastric Antral Vascular Ectasia (GAVE): Also known as "watermelon stomach," this condition involves dilated blood vessels in the stomach that can lead to chronic GI bleeding and microcytic anemia.
• Small Bowel Involvement: Hypomotility of the small bowel can cause bacterial overgrowth, leading to bloating, malabsorption, and macrocytic anemia (B12/folate deficiency). Wide-mouth diverticula can also form.
• Prognostic Factor: Severe dysfunction of the lower GI tract in SSc is associated with a poor overall prognosis.

D. Pulmonary Manifestations

• Main Pulmonary Complications: Interstitial Lung Disease (ILD) and Pulmonary Arterial Hypertension (PAH) are the leading causes of mortality in SSc.
• Interstitial Lung Disease (ILD) in SSc: Characterized by fibrosis and scarring of the lung parenchyma, often showing a "honeycombing" pattern on high-resolution CT (HRCT). Highest risk is associated with a positive Anti-Scl-70 antibody.
• Pulmonary Arterial Hypertension (PAH) in SSc: Defined by a mean pulmonary artery pressure ≥20 mmHg at rest. It is a common complication, especially in Limited Cutaneous SSc.

E. Renal Manifestations

• Scleroderma Renal Crisis (SRC): A life-threatening complication characterized by the abrupt onset of accelerated hypertension (>150/90 mmHg) and rapidly progressive renal failure.
• Risk Factors for SRC: SRC typically occurs within the first 4 years of disease, is more common in diffuse SSc, and is strongly associated with a positive Anti-RNA Polymerase III antibody. High-dose corticosteroid use is a major precipitating factor.
• SRC Pathophysiology: SRC is caused by microangiopathy in the kidney, leading to intimal proliferation of renal arterioles.
• Hallmark of SRC on Labs: Microangiopathic hemolytic anemia is a classic laboratory finding in SRC.

F. Cardiovascular & Musculoskeletal Manifestations

• Cardiac Involvement in SSc: Can manifest as pericarditis, pericardial effusions, myocardial fibrosis (leading to heart failure), and fibrosis of the conduction system (leading to heart block and arrhythmias).
• Musculoskeletal Involvement in SSc: Common features include arthralgia, morning stiffness, and prominent tendon friction rubs. Flexion contractures of the joints can develop due to skin thickening. An overlap with Rheumatoid Arthritis (erosive polyarthritis) can occur.

V. DIAGNOSIS

• Diagnostic Approach: The diagnosis of SSc is primarily clinical, based on characteristic skin induration and visceral organ manifestations.
• ACR/EULAR 2013 Criteria: A score of ≥9 establishes a definite diagnosis of Systemic Sclerosis. Skin thickening of the fingers of both hands extending proximal to the MCP joints is sufficient for diagnosis (score = 9).
• Antinuclear Antibody (ANA): ANA is positive in almost all patients with SSc, often in a nucleolar or speckled pattern.
• Scleroderma-Specific Antibodies:
  • Anti-Scl-70 (Anti-topoisomerase I): Highly specific for SSc, strongly associated with diffuse cutaneous SSc (dcSSc) and an increased risk for Interstitial Lung Disease (ILD).
  • Anticentromere Antibody (ACA): Highly specific for SSc, strongly associated with limited cutaneous SSc (lcSSc) and an increased risk for Pulmonary Arterial Hypertension (PAH).
  • Anti-RNA Polymerase III Antibody: Associated with diffuse cutaneous SSc (dcSSc) and a high risk for Scleroderma Renal Crisis (SRC) and an increased risk of malignancy around the time of SSc onset.
• Anemia in SSc:
  • Microcytic Anemia: May result from chronic GI bleeding from GAVE or esophagitis.
  • Macrocytic Anemia: May be caused by vitamin B12/folate deficiency from small-bowel bacterial overgrowth or as a side effect of methotrexate.
  • Microangiopathic Hemolytic Anemia: A hallmark of Scleroderma Renal Crisis (SRC), caused by mechanical RBC fragmentation.
• Inflammatory Markers: ESR and CRP are often normal in SSc. An elevated ESR may suggest a coexisting myositis or malignancy.

VI. TREATMENT & MANAGEMENT

• Treatment Goal: There is no cure for SSc. Treatment is aimed at alleviating symptoms, managing organ complications, and slowing disease progression.
• Role of Corticosteroids: Glucocorticoids are used cautiously at low doses (<5-10 mg/day prednisone) for inflammatory arthritis or early inflammatory dcSSc. High doses are strongly associated with an increased risk of Scleroderma Renal Crisis (SRC).
• Irreversibility of Skin Changes: It is important to note that established skin fibrosis and tightening are generally irreversible.

A. Organ-Specific Treatment

• Scleroderma Renal Crisis (SRC) Management:
  • First-line Treatment: Prompt initiation of ACE inhibitors (e.g., Captopril, Enalapril) is critical and life-saving.
  • Goal: The goal is to gradually lower blood pressure, not normalize it abruptly.
  • Refractory Cases: May require adding ARBs, CCBs, or other agents. Renal replacement therapy (dialysis) or kidney transplantation may be necessary.
• SSc-Associated Interstitial Lung Disease (ILD) Management:
  • Monitoring: Regular monitoring with HRCT scans and Pulmonary Function Tests (PFTs) is essential.
  • Immunosuppressive Therapy: Mycophenolate Mofetil (MMF) or Cyclophosphamide are used to stabilize lung function.
  • Antifibrotic Therapy: Nintedanib, a tyrosine kinase inhibitor, is approved to slow the rate of lung function decline in SSc-ILD.
• Pulmonary Arterial Hypertension (PAH) Management:
  • Treatment: Requires advanced vasodilator therapies including endothelin-1 receptor antagonists (Bosentan), PDE-5 inhibitors (Sildenafil), and prostacyclin analogues (Epoprostenol).
• Gastrointestinal Complication Management:
  • GERD: Managed with PPIs, prokinetic agents, and lifestyle modifications (elevating head of bed, small frequent meals).
  • GAVE: Bleeding is treated with endoscopic ablation (e.g., argon plasma coagulation).
  • Bacterial Overgrowth: Treated with rotating courses of antibiotics.
  • Severe Hypomotility: May require octreotide.
• Vascular / Raynaud's Phenomenon Management:
  • First-line: Dihydropyridine calcium channel blockers (e.g., Amlodipine, Nifedipine).
  • Advanced/Refractory: Options include PDE-5 inhibitors (Sildenafil), ARBs (Losartan), or intermittent IV prostaglandins.
  • Digital Ulcers: Bosentan can reduce the development of new ischemic ulcers. Low-dose aspirin is often used as an adjunctive agent.
• Skin & Joint Involvement Management:
  • Joints: Methotrexate can be used for SSc-associated arthritis.
  • Skin: Methotrexate may provide modest benefit for early skin involvement. Cyclophosphamide may also improve skin induration.

B. Advanced & Systemic Therapies

• Mycophenolate Mofetil (MMF): Increasingly used as a first-line agent, showing benefits for both skin induration and ILD with a better safety profile than cyclophosphamide.
• Tocilizumab (Anti-IL-6): An biologic agent that has shown improvement in both skin and lung involvement in SSc.
• Rituximab (Anti-CD20): Used in refractory cases with promising results for skin and lung disease.
• Hematopoietic Stem Cell Transplantation (HSCT): Reserved for patients with severe, rapidly progressive SSc; it is associated with significant treatment-related mortality but can induce long-term remission.

HIGH-YIELD COMPARISONS

• Limited vs. Diffuse SSc:
  • Limited (lcSSc): Skin thickening distal to elbows/knees. Associated with Anticentromere antibody. Higher risk for late-onset Pulmonary Arterial Hypertension (PAH).
  • Diffuse (dcSSc): Skin thickening includes proximal limbs/trunk. Associated with Anti-Scl-70 and Anti-RNA Pol III antibodies. Higher risk for early Interstitial Lung Disease (ILD) and Scleroderma Renal Crisis (SRC).
• Anti-Scl-70 vs. Anticentromere vs. Anti-RNA Pol III:
  • Anti-Scl-70 (Topoisomerase I): Marker for Diffuse SSc and high risk of Interstitial Lung Disease (ILD).
  • Anticentromere (ACA): Marker for Limited SSc and high risk of Pulmonary Arterial Hypertension (PAH).
  • Anti-RNA Polymerase III: Marker for Diffuse SSc and high risk of Scleroderma Renal Crisis (SRC) and malignancy.
• ILD vs. PAH in Scleroderma:
  • ILD (Interstitial Lung Disease): Fibrosis of lung tissue. Associated with Anti-Scl-70. Diagnosed with HRCT. Treated with immunosuppressants (MMF, Cyclophosphamide) and antifibrotics (Nintedanib).
  • PAH (Pulmonary Arterial Hypertension): High pressure in pulmonary arteries. Associated with Anticentromere. Diagnosed with right heart catheterization. Treated with vasodilators (Bosentan, Sildenafil).
• Localized vs. Systemic Scleroderma:
  • Localized: Involves only the skin (e.g., Morphea, Linear Scleroderma). No internal organ affectation.
  • Systemic: Involves both the skin and internal organs (e.g., lungs, kidneys, GI tract).
• Scleroderma Renal Crisis (SRC) vs. Other Hypertensive Emergencies: SRC is uniquely characterized by accelerated hypertension combined with microangiopathic hemolytic anemia and thrombocytopenia in the context of SSc. The first-line treatment is specifically ACE inhibitors.
• Scleroderma Raynaud's vs. Primary Raynaud's: In SSc, nailfold capillaroscopy shows abnormal changes (capillary dilation, hemorrhage, and dropout), whereas in primary Raynaud's, the capillaries are normal.
• Role of Steroids in SSc vs. other CTDs (e.g., Lupus): In SSc, steroids are used sparingly and at low doses due to the high risk of precipitating SRC. In active lupus, high-dose steroids are a cornerstone of treatment.
• Cyclophosphamide vs. Mycophenolate (MMF) for SSc-ILD: Both are used for immunosuppression. Cyclophosphamide is effective but has higher toxicity (e.g., hemorrhagic cystitis, malignancy). MMF is now often preferred due to a better long-term safety profile.
• Nintedanib vs. PPIs in SSc Treatment: Nintedanib is an antifibrotic drug specifically used to slow the progression of SSc-ILD. PPIs are used for symptomatic management of the very common GI complication of GERD.
• GAVE ("Watermelon Stomach") vs. Esophageal Dysmotility: Both are GI issues in SSc. GAVE is a vascular problem in the stomach causing chronic bleeding (microcytic anemia). Esophageal dysmotility is a motility problem causing GERD and dysphagia.
• Three Anemias of SSc:
  • Microcytic Anemia: Caused by chronic iron loss from GI bleeding (GAVE, esophagitis).
  • Macrocytic Anemia: Caused by malabsorption of Vitamin B12/Folate due to bacterial overgrowth.
  • Microangiopathic Hemolytic Anemia: A specific finding caused by mechanical damage to RBCs in the setting of Scleroderma Renal Crisis.

QA

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CHAPTER 360: SYSTEMIC SCLEROSIS (SCLERODERMA) AND RELATED DISORDERS

I. GENERAL PRINCIPLES & DEFINITION

1. What is the definition of Systemic Sclerosis (SSc)? | A multisystem connective tissue disease characterized by chronic inflammation, fibrosis, and obliterative vasculopathy.
2. What is the hallmark of Systemic Sclerosis pathogenesis? | Prominent microangiopathy in multiple vascular beds.
3. What are the three core pathophysiologic processes in SSc? | 1. Diffuse microangiopathy
   2. Inflammation and autoimmunity
   3. Fibrosis of vascular and visceral tissues.
4. Summarize the pathogenesis of SSc. | Endothelial damage leads to an immune response and growth factor release, causing myofibroblasts to produce excessive collagen and cause fibrosis.

II. ETIOLOGY & RISK FACTORS

5. What is the etiology of SSc? | Multifactorial: an interplay of genetic predisposition, epigenetic factors, infectious agents, and environmental exposures.
6. What is the genetic predisposition in SSc? | Associated with HLA class II genes on chromosome 6.
7. What are potential infectious triggers for SSc? (3) | 1. Parvovirus B19
   2. Epstein-Barr virus (EBV)
   3. Cytomegalovirus (CMV).
8. What are some environmental and drug exposures associated with SSc? | Silica (quartz), gadolinium, polyvinyl chloride, welding fumes, bleomycin, and cocaine.

III. CLASSIFICATION OF SCLERODERMA

9. What are the two main classifications of Scleroderma? | Localized Scleroderma and Systemic Sclerosis (SSc).
10. What is Localized Scleroderma? | A form of scleroderma that affects only the skin without internal organ involvement.
11. What is Morphea? | A type of localized scleroderma with single or multiple plaques of hardened skin, typically on the trunk.
12. What is Linear Scleroderma? | Bands of skin thickening on the legs, arms, or face. A facial presentation is "en coup de sabre."
13. What is Systemic Sclerosis (SSc)? | A form of scleroderma involving the skin and internal organs, divided into limited and diffuse types.
14. Describe the skin thickening in Limited Cutaneous Systemic Sclerosis (lcSSc). | It is restricted to areas distal to the elbows and knees, but may also involve the face and neck.
15. What are the manifestations of CREST syndrome, often associated with lcSSc? (5) | Calcinosis cutis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia.
16. Can Limited SSc have severe complications? | Yes, it is not necessarily "mild" and can have severe internal organ involvement like Pulmonary Arterial Hypertension (PAH).
17. Describe the skin thickening in Diffuse Cutaneous Systemic Sclerosis (dcSSc). | It involves proximal limbs (above elbows/knees) and/or the trunk.
18. What is the prognosis for dcSSc compared to lcSSc? | Associated with a higher risk of early and significant internal organ disease and poorer survival.
19. What is SSc Sine Scleroderma? | A rare variant with internal organ manifestations and autoantibodies of SSc but no skin thickening.

IV. CLINICAL FEATURES OF SYSTEMIC SCLEROSIS

A. General & Skin Manifestations 20. What is the hallmark skin finding in SSc? | Bilateral, symmetric skin thickening and induration, making the skin difficult to pinch. 21. What is the "salt and pepper" appearance in SSc? | Interspersed areas of hyperpigmentation and hypopigmentation. 22. What is Mauskopf Facie? | A "mouse-like" facial appearance due to skin tightening, with a pinched nose and thin lips. 23. What is Sclerodactyly? | Thickening and tightening of the skin on the fingers and/or toes. 24. What are other skin findings in SSc due to dermal sclerosis? | Dryness (xerosis), itching, and Telangiectasias (dilated capillaries).

B. Vascular Manifestations 25. What is the most common initial symptom of SSc? | Raynaud's Phenomenon. 26. What is the classic triphasic color change of Raynaud's? (3) | 1. Pallor (white)
2. Cyanosis (blue)
3. Hyperemia (red). 27. What are the complications of chronic, severe Raynaud's? | Digital pitting scars, ulcers, resorption of distal phalanges, and calcinosis cutis. 28. What is Calcinosis Cutis? | The formation of calcium phosphate crystals, often in the soft tissues of the fingers or over bony prominences.

C. Gastrointestinal Manifestations 29. What is the most common GI issue in SSc? | Gut dysmotility, which can affect any segment of the GI tract. 30. What is the most frequent GI manifestation of SSc? | Esophageal dysfunction, leading to chronic GERD and dysphagia. 31. What is Gastric Antral Vascular Ectasia (GAVE)? | "Watermelon stomach," which can lead to chronic GI bleeding and microcytic anemia. 32. How does small bowel involvement in SSc present? | Hypomotility causes bacterial overgrowth, leading to bloating, malabsorption, and macrocytic anemia. 33. What is a poor prognostic factor related to the GI tract in SSc? | Severe dysfunction of the lower GI tract.

D. Pulmonary Manifestations 34. What are the leading causes of mortality in SSc? | Interstitial Lung Disease (ILD) and Pulmonary Arterial Hypertension (PAH). 35. What is Interstitial Lung Disease (ILD) in SSc, and what antibody is it associated with? | Fibrosis and scarring of the lung parenchyma ("honeycombing" on HRCT), associated with Anti-Scl-70 antibody. 36. What is Pulmonary Arterial Hypertension (PAH) in SSc? | A mean pulmonary artery pressure ≥20 mmHg at rest; a common complication in Limited Cutaneous SSc.

E. Renal Manifestations 37. What is Scleroderma Renal Crisis (SRC)? | A life-threatening complication with abrupt onset of accelerated hypertension and rapidly progressive renal failure. 38. What are the risk factors for SRC? | Occurs early, common in diffuse SSc, associated with Anti-RNA Polymerase III, and precipitated by high-dose corticosteroids. 39. What is the pathophysiology of SRC? | Microangiopathy in the kidney, leading to intimal proliferation of renal arterioles. 40. What is the hallmark lab finding in SRC? | Microangiopathic hemolytic anemia.

F. Cardiovascular & Musculoskeletal Manifestations 41. How can SSc affect the heart? | Pericarditis, pericardial effusions, myocardial fibrosis (heart failure), and conduction system fibrosis (arrhythmias). 42. What are common musculoskeletal features of SSc? | Arthralgia, morning stiffness, prominent tendon friction rubs, and joint flexion contractures.

V. DIAGNOSIS

43. How is the diagnosis of SSc primarily made? | Clinically, based on characteristic skin induration and visceral organ manifestations.
44. What score on the ACR/EULAR 2013 criteria establishes a definite diagnosis of SSc? | A score of ≥9.
45. In almost all patients with SSc, what antibody test is positive? | Antinuclear Antibody (ANA).
46. What conditions are associated with the Anti-Scl-70 antibody? | Diffuse cutaneous SSc (dcSSc) and an increased risk for Interstitial Lung Disease (ILD).
47. What conditions are associated with the Anticentromere Antibody (ACA)? | Limited cutaneous SSc (lcSSc) and an increased risk for Pulmonary Arterial Hypertension (PAH).
48. What conditions are associated with the Anti-RNA Polymerase III Antibody? | Diffuse SSc, high risk for Scleroderma Renal Crisis (SRC), and increased risk of malignancy.
49. What can cause Microcytic Anemia in SSc? | Chronic GI bleeding from Gastric Antral Vascular Ectasia (GAVE) or esophagitis.
50. What can cause Macrocytic Anemia in SSc? | Vitamin B12/folate deficiency from small-bowel bacterial overgrowth.
51. What is the cause of Microangiopathic Hemolytic Anemia in SSc? | It is a hallmark of Scleroderma Renal Crisis (SRC), caused by mechanical RBC fragmentation.
52. How do inflammatory markers (ESR, CRP) typically present in SSc? | They are often normal.

VI. TREATMENT & MANAGEMENT

53. What is the goal of treatment for SSc? | To alleviate symptoms, manage organ complications, and slow disease progression, as there is no cure.
54. Why are glucocorticoids used cautiously in SSc? | High doses are strongly associated with an increased risk of Scleroderma Renal Crisis (SRC).
55. Are established skin fibrosis and tightening in SSc reversible? | No, they are generally irreversible.

A. Organ-Specific Treatment 56. What is the critical first-line treatment for Scleroderma Renal Crisis (SRC)? | Prompt initiation of ACE inhibitors (e.g., Captopril). 57. What is the blood pressure goal when treating SRC with ACE inhibitors? | To gradually lower blood pressure, not normalize it abruptly. 58. What are treatment options for refractory SRC? | Adding ARBs or CCBs; renal replacement therapy (dialysis) or kidney transplantation may be necessary. 59. How is SSc-associated Interstitial Lung Disease (ILD) monitored? | Regular monitoring with HRCT scans and Pulmonary Function Tests (PFTs). 60. What immunosuppressive therapies are used for SSc-ILD? | Mycophenolate Mofetil (MMF) or Cyclophosphamide. 61. What antifibrotic therapy is approved for SSc-ILD? | Nintedanib, a tyrosine kinase inhibitor. 62. How is Pulmonary Arterial Hypertension (PAH) managed in SSc? | Advanced vasodilator therapies like endothelin-1 receptor antagonists (Bosentan), PDE-5 inhibitors (Sildenafil), and prostacyclin analogues (Epoprostenol). 63. How is GERD managed in SSc? | With PPIs, prokinetic agents, and lifestyle modifications. 64. How is bleeding from GAVE ("watermelon stomach") treated? | With endoscopic ablation (e.g., argon plasma coagulation). 65. How is bacterial overgrowth treated in SSc? | With rotating courses of antibiotics. 66. What may be required for severe GI hypomotility in SSc? | Octreotide. 67. What is the first-line management for Raynaud's Phenomenon? | Dihydropyridine calcium channel blockers (e.g., Amlodipine, Nifedipine). 68. What are treatment options for advanced/refractory Raynaud's? | PDE-5 inhibitors (Sildenafil), ARBs (Losartan), or intermittent IV prostaglandins. 69. How can the development of new ischemic digital ulcers be reduced in SSc? | Bosentan. 70. What medication is used for SSc-associated arthritis? | Methotrexate. 71. What medications may provide modest benefit for early skin involvement in SSc? | Methotrexate or Cyclophosphamide.

B. Advanced & Systemic Therapies 72. Why is Mycophenolate Mofetil (MMF) increasingly used as a first-line agent in SSc? | It shows benefits for both skin induration and ILD with a better safety profile than cyclophosphamide. 73. What is the role of Tocilizumab (Anti-IL-6) in SSc? | A biologic agent that has shown improvement in both skin and lung involvement. 74. When is Rituximab (Anti-CD20) used in SSc? | Used in refractory cases with promising results for skin and lung disease. 75. When is Hematopoietic Stem Cell Transplantation (HSCT) considered for SSc? | Reserved for patients with severe, rapidly progressive SSc; it can induce long-term remission but has high mortality.

HIGH-YIELD COMPARISONS

76. In comparing Limited vs. Diffuse SSc, describe Limited SSc (lcSSc). | Skin thickening distal to elbows/knees. Associated with Anticentromere antibody. Higher risk for late-onset PAH.
77. In comparing Limited vs. Diffuse SSc, describe Diffuse SSc (dcSSc). | Skin thickening includes proximal limbs/trunk. Associated with Anti-Scl-70 and Anti-RNA Pol III. Higher risk for early ILD and SRC.
78. What are the associations of the Anti-Scl-70 (Topoisomerase I) antibody? | Marker for Diffuse SSc and high risk of Interstitial Lung Disease (ILD).
79. What are the associations of the Anticentromere (ACA) antibody? | Marker for Limited SSc and high risk of Pulmonary Arterial Hypertension (PAH).
80. What are the associations of the Anti-RNA Polymerase III antibody? | Marker for Diffuse SSc and high risk of Scleroderma Renal Crisis (SRC) and malignancy.
81. Compare ILD vs. PAH: Describe Interstitial Lung Disease (ILD) in scleroderma. | Fibrosis of lung tissue. Associated with Anti-Scl-70. Diagnosed with HRCT. Treated with immunosuppressants and antifibrotics.
82. Compare ILD vs. PAH: Describe Pulmonary Arterial Hypertension (PAH) in scleroderma. | High pressure in pulmonary arteries. Associated with Anticentromere. Diagnosed with right heart catheterization. Treated with vasodilators.
83. Compare Localized vs. Systemic Scleroderma: Describe Localized Scleroderma. | Involves only the skin (e.g., Morphea, Linear Scleroderma). No internal organ affectation.
84. Compare Localized vs. Systemic Scleroderma: Describe Systemic Scleroderma. | Involves both the skin and internal organs (e.g., lungs, kidneys, GI tract).
85. How does Scleroderma Renal Crisis (SRC) differ from other hypertensive emergencies? | Uniquely characterized by accelerated hypertension plus microangiopathic hemolytic anemia. First-line treatment is specifically ACE inhibitors.
86. How does Scleroderma Raynaud's differ from Primary Raynaud's on nailfold capillaroscopy? | In SSc, capillaries show dilation, hemorrhage, and dropout; in primary Raynaud's, capillaries are normal.
87. Compare the role of steroids in SSc vs. Lupus. | In SSc, steroids are used sparingly at low doses due to SRC risk. In active lupus, high-dose steroids are a cornerstone of treatment.
88. Compare Cyclophosphamide vs. Mycophenolate (MMF) for SSc-ILD. | MMF is now often preferred due to a better long-term safety profile than cyclophosphamide, which has higher toxicity.
89. Compare the use of Nintedanib vs. PPIs in SSc treatment. | Nintedanib is an antifibrotic for SSc-ILD. PPIs are for symptomatic management of GI complications like GERD.
90. Compare GAVE vs. Esophageal Dysmotility in SSc. | GAVE is a vascular issue in the stomach causing bleeding (microcytic anemia). Esophageal dysmotility is a motility issue causing GERD.
91. What are the three types of anemias in SSc and their causes? | 1. Microcytic: GI bleeding (GAVE, esophagitis).
    2. Macrocytic: B12/Folate malabsorption.
    3. Microangiopathic Hemolytic: Scleroderma Renal Crisis.

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Summary

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CHAPTER 371: OSTEOARTHRITIS

I. BACKGROUND & PATHOGENESIS

• Osteoarthritis (OA) is the most common type of arthritis and a leading cause of disability in the elderly.
• The pathogenesis of Osteoarthritis is conceptualized as "Joint Failure," resulting from a combination of risk factors, an initiating event, and the failure of the joint's protective mechanisms.
• The pathologic "sine qua non" (an essential condition) for a diagnosis of Osteoarthritis is the loss of hyaline articular cartilage.
• In Osteoarthritis, damaged hyaline cartilage is replaced by fibrocartilage, which is not as tensile or effective.
• Chondrocytes in articular cartilage are incapable of regenerating, meaning cartilage is a non-renewable tissue.
• In the context of Osteoarthritis pathogenesis, strong muscles absorb load and stabilize joints; when athletic activity stops, muscle disuse leads to atrophy, increasing the load on cartilage and making prior asymptomatic damage painful.

II. RISK FACTORS

• The two major categories of risk factors for Osteoarthritis are joint vulnerability (e.g., increased age, genetics) and joint loading (e.g., obesity, repeated joint use).
• Age is the most potent risk factor for Osteoarthritis, with radiographic evidence being rare in individuals under 40 years old.
• Obesity is a potent risk factor for the development of knee Osteoarthritis, and to a lesser extent, hip Osteoarthritis, primarily through increased joint loading.
• Genetics plays a role in Osteoarthritis; a family history of nodular hand OA increases the risk for an individual by 50%.
• Repetitive occupational tasks are a risk factor for Osteoarthritis; for example, farmers are at high risk for hip OA, while miners are at risk for knee and spine OA.
• Commonly affected joints in Osteoarthritis include the cervical and lumbosacral spine, hip, knee, distal and proximal interphalangeal joints (DIPs/PIPs), and the base of the thumb (1st carpometacarpal).
• Joints typically spared in Osteoarthritis include the wrist, elbow, and ankle; pain in these joints warrants consideration of a different diagnosis.

III. CLINICAL FEATURES

• In early Osteoarthritis, pain is typically episodic and triggered by overuse of the joint.
• As Osteoarthritis progresses, joint pain can become continuous, occur at rest, and even be nocturnal.
• A key clinical feature of Osteoarthritis is brief morning stiffness, characteristically lasting less than 30 minutes, which helps distinguish it from inflammatory arthritis like Rheumatoid Arthritis.
• Heberden's nodes are bony nodules found on the distal interphalangeal (DIP) joints in hand Osteoarthritis.
• Bouchard's nodes are bony nodules found on the proximal interphalangeal (PIP) joints in hand Osteoarthritis.
• Osteoarthritis of the 1st carpometacarpal joint at the base of the thumb should be considered in patients complaining of a stinging pain with pinching, gripping, or twisting objects.
• A varus (bow-legged) deformity in a patient with knee pain suggests cartilage loss in the medial compartment of the knee due to Osteoarthritis.
• A valgus (knock-knee) deformity in a patient with knee pain suggests cartilage loss in the lateral compartment of the knee due to Osteoarthritis.

IV. DIAGNOSIS

• The diagnosis of Osteoarthritis is primarily made clinically, and routine blood tests are not usually needed.
• If performed, synovial fluid analysis in Osteoarthritis shows non-inflammatory fluid, with a white blood cell (WBC) count of less than 2,000 cells/µL.
• Imaging is not usually necessary for an initial diagnosis of Osteoarthritis and is often used to rule out other conditions like fractures.
• The severity of pain in Osteoarthritis correlates poorly with radiographic findings, as the cartilage itself has no nerve supply.
• The key radiographic findings in Osteoarthritis are:
  1. Joint space narrowing (a surrogate for hyaline articular cartilage loss).
  2. Subchondral thickness and sclerosis.
  3. Osteophytes (bony outgrowths at joint margins).

V. TREATMENT

• The main goals of Osteoarthritis treatment are to alleviate pain and minimize the loss of physical function.
• Non-pharmacologic management is a cornerstone of Osteoarthritis treatment and includes patient education to avoid painful activities, weight loss, and exercise (aerobic and resistance training).
• For Osteoarthritis, physical management includes unloading the affected joint through the use of a brace, splint, cane, or crutch.
• First-line pharmacotherapy for Osteoarthritis is often Paracetamol due to its favorable side-effect profile when used at the appropriate dose.
• NSAIDs and COX-2 inhibitors are more effective than paracetamol for Osteoarthritis pain but are not recommended for daily use due to potential side effects.
• Intra-articular glucocorticoid injections for Osteoarthritis offer short-term pain relief and are typically reserved for larger joints like the knee.
• Intra-articular hyaluronic acid injections for Osteoarthritis have a slower onset of action than corticosteroids but may provide longer-lasting relief.
• Surgical options for severe Osteoarthritis include joint realignment or total joint arthroplasty (replacement) of the knee or hip.
• There is currently no sufficient evidence to support cartilage regeneration techniques, including stem cell therapy, for the treatment of Osteoarthritis.

CHAPTER 370/372: GOUT AND OTHER CRYSTAL-ASSOCIATED ARTHROPATHIES

I. ACUTE MONOARTHRITIS & SEPTIC ARTHRITIS

• The primary differential diagnoses for an acute, red, hot, swollen joint (acute monoarthritis) are:
  1. Crystal-induced arthritis (e.g., Gout).
  2. Trauma (may cause hemarthrosis).
  3. Septic arthritis.
• Septic arthritis must be ruled out emergently in cases of acute monoarthritis, as irreversible joint damage can occur in less than 24-48 hours if left untreated.
• Arthrocentesis (joint aspiration) is a critical diagnostic procedure for acute monoarthritis to analyze the synovial fluid.
• In septic arthritis, the synovial fluid is typically purulent or turbid, with a very high WBC count (often >50,000/uL, >90% neutrophils), and a positive Gram stain and culture.
• The most common causative agent for non-gonococcal bacterial arthritis is Staphylococcus aureus.
• The knee is the most commonly involved joint in non-gonococcal bacterial arthritis, which typically presents as a monoarticular arthritis.
• Risk factors for non-gonococcal bacterial arthritis include Rheumatoid Arthritis, Diabetes Mellitus, use of glucocorticoids, and immunodeficiencies.
• Gonococcal arthritis is more likely to occur in women, and may present as Disseminated Gonococcal Infection (DGI) with fever, rash, and articular symptoms.
• The recommended treatment for gonococcal arthritis is Ceftriaxone.
• Poncet's disease is a reactive symmetric polyarthritis associated with an untreated Mycobacterium tuberculosis infection elsewhere in the body; the joint culture is negative.
• Sporotrichosis is a fungal arthritis that can cause chronic, indolent monoarthritis, often seen in gardeners ("Rose gardener's disease").

II. GOUT: PATHOPHYSIOLOGY & CLINICAL FEATURES

• Gout is a metabolic disease caused by chronic hyperuricemia leading to the deposition of monosodium urate (MSU) crystals in and around the joints.
• The pathophysiology of an acute gout flare involves the shedding of MSU crystals into the joint, which triggers a potent inflammatory response from synovial macrophages and other cells.
• Key risk factors for Gout include hyperuricemia, obesity, Western diet, alcohol consumption, and use of medications like diuretics (e.g., Furosemide) and low-dose aspirin.
• A classic Gout attack presents as an intensely painful, warm, red, and swollen joint.
• The first attack of Gout is usually monoarticular, with the first metatarsophalangeal (MTP) joint being the most commonly affected site, a condition known as "podagra".

III. GOUT: DIAGNOSIS

• The gold standard for diagnosing Gout is the identification of needle-shaped, negatively birefringent monosodium urate (MSU) crystals in synovial fluid via polarized light microscopy.
• Under a polarizing microscope with a first-order compensator, MSU crystals in Gout appear yellow when parallel to the axis of the compensator and blue when perpendicular.
• During an acute Gout flare, serum uric acid (SUA) levels can be normal or even low due to cytokine-mediated uricosuria; levels should be rechecked 4-6 weeks after the flare resolves.
• On ultrasound, MSU crystal deposition on the surface of cartilage can create a "double contour" sign, which can be seen even in asymptomatic hyperuricemic patients.
• Radiographic findings in chronic Gout can include "rat-bite" erosions, which are punched-out erosions with sclerotic margins and overhanging edges.

IV. GOUT: TREATMENT

• The treatment for an acute Gout attack focuses on anti-inflammatory therapy with NSAIDs, Colchicine, or glucocorticoids.
• Urate-lowering therapy (ULT) such as Allopurinol or Febuxostat should NOT be initiated during an active Gout flare, as it can potentially worsen the attack.
• Prophylaxis against Gout flares with low-dose Colchicine (0.5 mg OD) or low-dose NSAIDs is often started concurrently with the initiation of urate-lowering therapy.
• The target serum uric acid (SUA) level for patients with Gout is typically <6 mg/dL.
• For patients with tophaceous Gout (visible tophi), a lower SUA target of <5 mg/dL is recommended to promote tophi dissolution.
• Indications for starting long-term urate-lowering therapy (ULT) include:
  1. Two or more Gout flares per year.
  2. Presence of tophi.
  3. History of uric acid kidney stones.
  4. Evidence of radiographic damage due to Gout.

V. OTHER CRYSTAL-ASSOCIATED ARTHROPATHIES

• Calcium Pyrophosphate Deposition (CPPD) disease can cause an acute inflammatory arthritis known as "pseudogout".
• The definitive diagnosis of CPPD is made by identifying rhomboid or rod-shaped, weakly positively birefringent crystals in the synovial fluid.
• CPPD most commonly affects the knee and can be precipitated by trauma, severe illness, or parathyroidectomy.
• On imaging, CPPD is associated with chondrocalcinosis, which appears as punctate or linear radiodense deposits in cartilage.
• Calcium Apatite Deposition Disease involves the deposition of basic calcium phosphate crystals, which are typically not visible on standard polarized light microscopy.
• Calcium Apatite Deposition is associated with a destructive arthropathy of the shoulder known as "Milwaukee shoulder".
• Calcium Oxalate Deposition Disease is a rare condition seen mainly in patients with chronic renal failure on hemodialysis.
• The diagnosis of Calcium Oxalate Deposition Disease is confirmed by finding envelope-shaped or bipyramidal, strongly birefringent crystals in the synovial fluid.

HIGH-YIELD COMPARISONS

• Osteoarthritis vs. Gout (Clinical Presentation): In Osteoarthritis, pain is insidious and related to use, with morning stiffness lasting <30 minutes. In Gout, the onset of pain is acute, severe, and inflammatory, often waking the patient from sleep.
• Osteoarthritis vs. Septic Arthritis (Synovial Fluid): Osteoarthritis fluid is non-inflammatory (WBC < 2,000/µL). Septic arthritis fluid is purulent and highly inflammatory (WBC > 50,000/µL, >90% neutrophils, positive culture).
• Gout vs. Pseudogout (Crystals): Gout is caused by needle-shaped, negatively birefringent MSU crystals. Pseudogout (CPPD) is caused by rhomboid-shaped, weakly positively birefringent CPP crystals.
• Gout Crystal Birefringence (Color Rule): In Gout, MSU crystals appear Yellow when parallel to the compensator axis and Blue when Perpendicular. (Mnemonic: Y-L-L for YeLLow-paraLLel).
• Pseudogout Crystal Birefringence (Color Rule): In Pseudogout, CPP crystals appear Blue when Parallel to the compensator axis and Yellow when Perpendicular.
• Starting Urate-Lowering Therapy (ULT) in Gout: ULT (e.g., Allopurinol) should not be started during an acute flare. The acute inflammation should be treated first, and ULT can be initiated once the flare has resolved, typically with prophylactic anti-inflammatory cover.
• Affected Joints in OA vs. Gout: OA commonly affects weight-bearing joints (knees, hips) and hands (DIPs, PIPs). Gout's classic initial presentation is in the 1st MTP joint (podagra), but it can also affect the midfoot, ankles, and knees.
• Hand OA vs. Gout in Hands: Hand OA presents as bony nodules (Heberden's/Bouchard's) at the DIP/PIP joints. Gout can also affect hand joints but presents as acute inflammatory attacks and can form tophi.
• Radiographic Findings in OA vs. Gout: OA shows joint space narrowing, subchondral sclerosis, and osteophytes. Chronic Gout shows characteristic "rat-bite" or punched-out erosions with overhanging edges.
• Aspirin's Effect on Uric Acid: Low-dose aspirin (<1-2 g/day) can increase serum uric acid levels by inhibiting renal tubular secretion and is a risk factor for Gout. High-dose aspirin has a uricosuric effect (lowers uric acid).
• Furosemide's Effect on Uric Acid: Loop diuretics like furosemide increase uric acid reabsorption in the proximal tubule, leading to hyperuricemia and increasing the risk for Gout attacks.
• Non-gonococcal vs. Gonococcal Septic Arthritis: Non-gonococcal arthritis is often a severe monoarthritis in an older patient with comorbidities (e.g., RA, DM), and fluid culture is usually positive. Gonococcal arthritis is more common in younger, sexually active individuals (especially women) and may present as a polyarthralgia/dermatitis syndrome (DGI) with less consistently positive cultures.
• Gout vs. CPPD vs. Calcium Oxalate (Key Associations): Gout is associated with metabolic syndrome, alcohol, and diuretics. CPPD is associated with older age, hyperparathyroidism, and hemochromatosis. Calcium Oxalate arthritis is almost exclusively seen in patients with end-stage renal disease.
• Glucocorticoids in OA vs. Gout: In OA, glucocorticoids are used via intra-articular injection for localized, short-term relief. In Gout, oral, intramuscular, or intra-articular glucocorticoids are a primary option for treating acute inflammatory flares.

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CHAPTER 371: OSTEOARTHRITIS

I. BACKGROUND & PATHOGENESIS

1. What is the most common type of arthritis and a leading cause of disability in the elderly? | Osteoarthritis
2. The pathogenesis of Osteoarthritis is conceptualized as what process? | "Joint Failure"
3. What is the pathologic "sine qua non" (essential condition) for a diagnosis of Osteoarthritis? | The loss of hyaline articular cartilage.
4. In Osteoarthritis, what is damaged hyaline cartilage replaced by? | Fibrocartilage.
5. In articular cartilage, are chondrocytes capable of regenerating? | No, cartilage is a non-renewable tissue.
6. In Osteoarthritis pathogenesis, what is the effect of muscle disuse and atrophy? | It increases the load on cartilage, making prior asymptomatic damage painful.

II. RISK FACTORS 7. What are the two major categories of risk factors for Osteoarthritis? | 1. Joint vulnerability
2. Joint loading 8. What is the most potent risk factor for Osteoarthritis? | Age. 9. Obesity is a potent risk factor for knee and, to a lesser extent, hip Osteoarthritis, primarily through what mechanism? | Increased joint loading. 10. A family history of what type of Osteoarthritis increases an individual's risk by 50%? | Nodular hand Osteoarthritis. 11. Repetitive occupational tasks are a risk factor for Osteoarthritis; farmers are at high risk for hip OA, while miners are at risk for what? | Knee and spine Osteoarthritis. 12. What are the commonly affected joints in Osteoarthritis? (6) | 1. Cervical and lumbosacral spine
2. Hip
3. Knee
4. DIPs/PIPs
5. Base of thumb (1st carpometacarpal) 13. Pain in which joints, typically spared in Osteoarthritis, warrants consideration of a different diagnosis? (3) | 1. Wrist
2. Elbow
3. Ankle

III. CLINICAL FEATURES 14. In early Osteoarthritis, how is pain typically described? | Episodic and triggered by overuse. 15. As Osteoarthritis progresses, how can the joint pain change? | It can become continuous, occur at rest, and even be nocturnal. 16. A key feature of Osteoarthritis is brief morning stiffness, characteristically lasting how long? | Less than 30 minutes. 17. What are the bony nodules found on the distal interphalangeal (DIP) joints in hand Osteoarthritis called? | Heberden's nodes. 18. What are the bony nodules found on the proximal interphalangeal (PIP) joints in hand Osteoarthritis called? | Bouchard's nodes. 19. Osteoarthritis of the 1st carpometacarpal joint should be considered with stinging pain during what actions? | Pinching, gripping, or twisting objects. 20. A varus (bow-legged) deformity with knee pain suggests cartilage loss in which compartment due to Osteoarthritis? | Medial compartment. 21. A valgus (knock-knee) deformity with knee pain suggests cartilage loss in which compartment due to Osteoarthritis? | Lateral compartment.

IV. DIAGNOSIS 22. How is the diagnosis of Osteoarthritis primarily made? | Clinically. 23. What is the characteristic synovial fluid white blood cell (WBC) count in Osteoarthritis? | Less than 2,000 cells/µL (non-inflammatory). 24. Is imaging usually necessary for an initial diagnosis of Osteoarthritis? | No, it is often used to rule out other conditions. 25. How well does the severity of pain in Osteoarthritis correlate with radiographic findings? | It correlates poorly. 26. What are the 3 key radiographic findings in Osteoarthritis? | 1. Joint space narrowing
2. Subchondral thickness and sclerosis
3. Osteophytes

V. TREATMENT 27. What are the two main goals of Osteoarthritis treatment? | 1. Alleviate pain
2. Minimize loss of physical function 28. What are 3 non-pharmacologic cornerstones of Osteoarthritis treatment? | 1. Patient education
2. Weight loss
3. Exercise 29. To unload the affected joint in Osteoarthritis, what physical management tools can be used? | A brace, splint, cane, or crutch. 30. What is often the first-line pharmacotherapy for Osteoarthritis? | Paracetamol. 31. Are NSAIDs and COX-2 inhibitors recommended for daily use in Osteoarthritis? | No, due to potential side effects. 32. What duration of pain relief do intra-articular glucocorticoid injections offer for Osteoarthritis? | Short-term pain relief. 33. Compared to corticosteroids, what is the onset and duration of intra-articular hyaluronic acid injections for Osteoarthritis? | Slower onset, but may provide longer-lasting relief. 34. What are the surgical options for severe Osteoarthritis of the knee or hip? (2) | 1. Joint realignment
2. Total joint arthroplasty (replacement) 35. Is there sufficient evidence to support cartilage regeneration techniques like stem cell therapy for Osteoarthritis? | No.

CHAPTER 370/372: GOUT AND OTHER CRYSTAL-ASSOCIATED ARTHROPATHIES

I. ACUTE MONOARTHRITIS & SEPTIC ARTHRITIS 36. What are the 3 primary differential diagnoses for an acute, red, hot, swollen joint (acute monoarthritis)? | 1. Crystal-induced arthritis (e.g., Gout)
2. Trauma
3. Septic arthritis 37. Why must septic arthritis be ruled out emergently in acute monoarthritis? | Irreversible joint damage can occur in less than 24-48 hours. 38. What is the critical diagnostic procedure for acute monoarthritis? | Arthrocentesis (joint aspiration). 39. What are the typical synovial fluid findings in septic arthritis? | Purulent/turbid fluid, WBC >50,000/uL, positive Gram stain/culture. 40. What is the most common causative agent for non-gonococcal bacterial arthritis? | Staphylococcus aureus. 41. What is the most commonly involved joint in non-gonococcal bacterial arthritis? | The knee. 42. What are 4 risk factors for non-gonococcal bacterial arthritis? | 1. Rheumatoid Arthritis
2. Diabetes Mellitus
3. Glucocorticoids
4. Immunodeficiencies 43. Gonococcal arthritis may present as Disseminated Gonococcal Infection (DGI) with what symptoms? | Fever, rash, and articular symptoms. 44. What is the recommended treatment for gonococcal arthritis? | Ceftriaxone. 45. What is Poncet's disease? | A reactive symmetric polyarthritis associated with an untreated Mycobacterium tuberculosis infection. 46. What fungal arthritis, known as "Rose gardener's disease," can cause chronic, indolent monoarthritis? | Sporotrichosis.

II. GOUT: PATHOPHYSIOLOGY & CLINICAL FEATURES 47. Gout is a metabolic disease caused by chronic hyperuricemia leading to deposition of what type of crystals? | Monosodium urate (MSU) crystals. 48. What event triggers the potent inflammatory response in an acute gout flare? | The shedding of MSU crystals into the joint. 49. What are 5 key risk factors for Gout? | 1. Hyperuricemia
2. Obesity
3. Western diet
4. Alcohol consumption
5. Certain medications (diuretics, low-dose aspirin) 50. How does a classic Gout attack present? | An intensely painful, warm, red, and swollen joint. 51. What is the most common site for a first Gout attack, and what is this condition called? | First metatarsophalangeal (MTP) joint; known as "podagra".

III. GOUT: DIAGNOSIS 52. What is the gold standard for diagnosing Gout? | Identification of needle-shaped, negatively birefringent MSU crystals. 53. In Gout, what color are MSU crystals when parallel to the compensator axis, and when perpendicular? | Yellow when parallel, blue when perpendicular. 54. During an acute Gout flare, what can be observed about serum uric acid (SUA) levels? | Levels can be normal or even low. 55. What characteristic sign can be seen on ultrasound due to MSU crystal deposition in Gout? | "Double contour" sign. 56. What are the characteristic radiographic findings in chronic Gout? | "Rat-bite" erosions.

IV. GOUT: TREATMENT 57. The treatment for an acute Gout attack focuses on what type of therapy? | Anti-inflammatory therapy (NSAIDs, Colchicine, or glucocorticoids). 58. Should urate-lowering therapy (ULT) like Allopurinol be initiated during an active Gout flare? | No. 59. What is often started concurrently with urate-lowering therapy to prevent Gout flares? | Prophylaxis with low-dose Colchicine or NSAIDs. 60. What is the typical target serum uric acid (SUA) level for patients with Gout? | <6 mg/dL. 61. What is the recommended target serum uric acid (SUA) level for patients with tophaceous Gout? | <5 mg/dL. 62. What are the 4 main indications for starting long-term urate-lowering therapy (ULT) for Gout? | 1. Two or more Gout flares per year
2. Presence of tophi
3. History of uric acid kidney stones
4. Radiographic damage due to Gout

V. OTHER CRYSTAL-ASSOCIATED ARTHROPATHIES 63. What disease causes an acute inflammatory arthritis known as "pseudogout"? | Calcium Pyrophosphate Deposition (CPPD) disease. 64. How is the definitive diagnosis of CPPD (pseudogout) made? | By identifying rhomboid, weakly positively birefringent crystals. 65. What joint does CPPD (pseudogout) most commonly affect? | The knee. 66. On imaging, CPPD is associated with what finding? | Chondrocalcinosis. 67. Are the crystals in Calcium Apatite Deposition Disease visible on standard polarized light microscopy? | No, they are typically not visible. 68. Calcium Apatite Deposition is associated with a destructive arthropathy of the shoulder known as what? | "Milwaukee shoulder". 69. Calcium Oxalate Deposition Disease is mainly seen in which patient population? | Patients with chronic renal failure on hemodialysis. 70. What is the characteristic shape of crystals found in Calcium Oxalate Deposition Disease? | Envelope-shaped or bipyramidal.

HIGH-YIELD COMPARISONS

71. Compare the clinical presentation of Osteoarthritis vs. Gout. | Osteoarthritis: Insidious onset, pain related to use.
    Gout: Acute onset, severe, inflammatory pain.
72. Compare the synovial fluid in Osteoarthritis vs. Septic Arthritis. | Osteoarthritis: Non-inflammatory (WBC < 2,000/µL).
    Septic Arthritis: Purulent, inflammatory (WBC > 50,000/µL).
73. Compare the crystals in Gout vs. Pseudogout. | Gout: Needle-shaped, negatively birefringent MSU crystals.
    Pseudogout: Rhomboid-shaped, weakly positively birefringent CPP crystals.
74. What is the color rule for Gout crystals under a polarizing microscope? | Yellow when parallel to the compensator axis (Mnemonic: Y-L-L, YeLLow-paraLLel).
75. What is the color rule for Pseudogout crystals under a polarizing microscope? | Blue when parallel to the compensator axis.
76. When should urate-lowering therapy (ULT) be started in Gout? | After the acute flare has resolved, not during.
77. Compare the commonly affected joints in Osteoarthritis vs. Gout. | Osteoarthritis: Weight-bearing joints (knees, hips), hands.
    Gout: 1st MTP joint (podagra), midfoot, ankles.
78. Compare the presentation of Osteoarthritis vs. Gout in the hands. | Hand Osteoarthritis: Bony nodules (Heberden's/Bouchard's).
    Gout: Acute inflammatory attacks and tophi.
79. Compare the radiographic findings in Osteoarthritis vs. chronic Gout. | Osteoarthritis: Joint space narrowing, osteophytes.
    Chronic Gout: "Rat-bite" erosions.
80. What is the effect of low-dose aspirin on serum uric acid levels? | It can increase serum uric acid levels, acting as a risk factor for Gout.
81. What is the effect of loop diuretics like furosemide on uric acid levels? | Increases uric acid reabsorption, leading to hyperuricemia.
82. Compare non-gonococcal vs. gonococcal septic arthritis. | Non-gonococcal: Monoarthritis, older patient, comorbidities.
    Gonococcal: Younger, sexually active patient, may have dermatitis/polyarthralgia.
83. Name a key association for Gout, CPPD, and Calcium Oxalate arthritis respectively. | Gout: Metabolic syndrome.
    CPPD: Hyperparathyroidism.
    Calcium Oxalate: End-stage renal disease.
84. Compare the use of glucocorticoids in Osteoarthritis vs. Gout. | Osteoarthritis: Intra-articular for localized relief.
    Gout: Primary option for treating acute flares.

5

Summary

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CHAPTER 358: RHEUMATOID ARTHRITIS (RA)

I. INTRODUCTION & CLINICAL FEATURES

• Rheumatoid Arthritis (RA) is the most common form of chronic inflammatory arthritis, characterized by systemic polyarthritis of unknown etiology.
• The goal in Rheumatoid Arthritis is to diagnose and treat early before irreversible joint damage and functional disability ensue.
• Rheumatoid Arthritis is more common in women than men, with an incidence that increases between 25 and 55 years of age.
• A key clinical feature of Rheumatoid Arthritis is early morning stiffness lasting more than one hour, which improves with activity.
• Rheumatoid Arthritis typically presents with symmetrical joint pain and swelling, with a predilection for the small joints of the hands (MCPs, PIPs) and feet.
• A frequent hallmark of Rheumatoid Arthritis is flexor tendon tenosynovitis.
• The initial pattern of joint involvement in Rheumatoid Arthritis can be monoarticular, oligoarticular (≤ 4 joints), or polyarticular (> 5 joints), resulting from inflammation of joints, tendons, and bursae.

II. PATHOGENESIS

• Genetic predisposition for Rheumatoid Arthritis is linked to MHC class II alleles, particularly HLA-DRB1 and HLA-DR4 related alleles.
• Antibodies to cyclic citrullinated polypeptides (anti-CCP) are associated with the pathogenesis of Rheumatoid Arthritis.
• Environmental factors that are risks for Rheumatoid Arthritis include cigarette smoking and infectious agents like Porphyromonas gingivalis.
• The pathogenesis of Rheumatoid Arthritis involves CD4+ T-cell activation, which stimulates B cells, macrophages, and fibroblasts to secrete proinflammatory mediators like TNF-α, IL-1, and IL-6.
• In Rheumatoid Arthritis, TNF-α inhibits bone formation (via the Wnt pathway) and stimulates osteoclast-mediated bone destruction (via the RANKL pathway).

III. MANIFESTATIONS

• Chronic Hand Deformities in Rheumatoid Arthritis*:
  1. Swan neck deformity: Characterized by hyperextension of the PIP joint and flexion of the DIP joint.
  2. Boutonniere deformity: Characterized by flexion of the PIP joint and hyperextension of the DIP joint.
  3. Ulnar deviation: A drift of the fingers toward the ulna at the MCP joints.
  4. MCP joint subluxation.
  5. Intrinsic muscle atrophy: Worsens and accentuates the deformities by removing dynamic joint stabilization.
• Chronic hand deformities in Rheumatoid Arthritis require long-standing disease and are not typically seen in the early stages.
• Extra-Articular Manifestations of Rheumatoid Arthritis:
  • Ocular: Scleritis and secondary Sjogren’s syndrome (sicca syndrome).
  • Vascular: Rheumatoid vasculitis, which can manifest as Livedo reticularis.
  • Dermatologic: Rheumatoid nodules, seen in chronic, seropositive disease.
  • Pulmonary: Interstitial lung disease (ILD), which can be exacerbated by certain medications like methotrexate.

IV. DIAGNOSIS

• The 2010 ACR/EULAR Criteria for Rheumatoid Arthritis are used for diagnosis, requiring a score of ≥ 6 based on four domains: joint involvement, serology, acute-phase reactants, and duration of symptoms.
• Under the 2010 criteria for RA, "small joints" include the MCPs, PIPs, MTPs (2-5), thumb IP, and wrists. "Large joints" include shoulders, elbows, hips, knees, and ankles.
• For arthritis lasting less than 6 weeks, viral arthritis (e.g., Chikungunya) should be considered as a differential diagnosis for Rheumatoid Arthritis.
• Rheumatoid Factor (RF):
  • An autoantibody (commonly IgM) directed against the Fc portion of IgG.
  • A high titer of RF is a prognosticating factor, suggesting a more severe disease with extra-articular manifestations.
  • Rheumatoid factor is sensitive but not specific for RA, as low titers can be seen in various infectious and chronic inflammatory conditions.
• Anti-Cyclic Citrullinated Peptide (anti-CCP):
  • Antibodies that are more specific for Rheumatoid Arthritis than RF.
  • The presence of anti-CCP antibodies is useful for the initial evaluation of unexplained joint inflammation and often indicates a more aggressive disease with a tendency for bone erosions.
• Synovial Fluid Analysis in Rheumatoid Arthritis:
  • Shows an inflammatory pattern with a WBC count of 5,000-50,000/μL, predominantly neutrophils.
  • This test is not diagnostic for RA but is useful to confirm inflammatory arthritis and rule out infection or crystal-induced arthritis.
• Joint Imaging in Rheumatoid Arthritis:
  • Plain radiography in early RA may show periarticular osteopenia; erosions are a later finding.
  • MRI is highly sensitive for detecting early synovitis and joint effusions.
  • Ultrasound is useful for detecting erosions and synovitis, though it is operator-dependent.

V. MANAGEMENT

• The primary goal of Rheumatoid Arthritis treatment is to achieve remission or low disease activity.
• Treatment principles for Rheumatoid Arthritis include: 1) Early, aggressive treatment, 2) Frequent modification of DMARDs, 3) Individualization, 4) Minimal glucocorticoid use, and 5) Achieving remission.
• Patients with Rheumatoid Arthritis should be monitored regularly (e.g., every 3 months) to assess disease activity (using tools like the DAS28 joint count) and screen for medication side-effects.
• Pharmacologic agents for Rheumatoid Arthritis:
  • NSAIDs: Used as adjunct therapy for symptomatic relief.
  • Steroids: Used for rapid disease control during initial diagnosis and for managing acute flares. The goal is to use the lowest possible dose (<7.5 mg/day prednisone equivalent).
  • Conventional synthetic DMARDs (cDMARDs): Methotrexate is the drug of choice and anchor drug. It is typically dosed once a week. Patients on methotrexate should receive folic acid supplementation.
  • Biologic DMARDs (bDMARDs): Targeted therapies like Anti-TNF agents (e.g., Infliximab, Etanercept), Anti-IL-6 agents, Abatacept, and Rituximab. A common adverse effect of anti-TNF agents is the reactivation of latent tuberculosis.
  • Targeted synthetic DMARDs (tsDMARDs): JAK inhibitors such as Tofacitinib and Baricitinib, which are oral medications.

CHAPTER 362: SPONDYLOARTHRITIS (SpA)

I. SPECTRUM OF SPONDYLOARTHROPATHIES

• Spondyloarthropathies (SpA) are a group of inflammatory diseases that share common features, including sacroiliitis, enthesitis, and a strong association with HLA-B27.
• The three most common types of Spondyloarthropathy are Ankylosing Spondylitis, Psoriatic Arthritis, and Reactive Arthritis.
• SpA typically presents with an asymmetric, oligoarticular (four or less joints) inflammatory arthritis, often involving large joints in the lower limbs. This contrasts with the symmetric polyarthritis of RA.
• Key musculoskeletal manifestations of SpA include sacroiliitis, inflammatory spinal lesions, enthesitis (inflammation at tendon/ligament insertion sites), and dactylitis ("sausage digits").

II. ANKYLOSING SPONDYLITIS (AS)

• Ankylosing Spondylitis (AS) is a chronic inflammatory disorder primarily affecting the axial skeleton, though peripheral joints can be involved.
• Ankylosing Spondylitis typically begins in the 2nd or 3rd decade of life, is more common in men, and has a strong association with HLA-B27.
• Symmetrical sacroiliitis is often the earliest manifestation of Ankylosing Spondylitis.
• The radiographic hallmark of advanced Ankylosing Spondylitis is the "bamboo spine," resulting from vertebral body fusion by marginal syndesmophytes.
• The Schober’s test is used to assess for decreased lumbar spine flexion, a common finding in Ankylosing Spondylitis.
• Treatment for Ankylosing Spondylitis includes:
  • Exercise: Critically important to maintain posture and range of motion.
  • NSAIDs: First-line therapy to reduce pain and tenderness.
  • Biologics: Anti-TNF and Anti-IL17 agents are highly effective and often used as first-line therapy.
  • Sulfasalazine: Used for peripheral arthritis associated with AS.
• A major and concerning complication of advanced Ankylosing Spondylitis is spinal fracture.

III. PSORIATIC ARTHRITIS (PsA)

• Psoriatic Arthritis (PsA) is an inflammatory musculoskeletal disease that characteristically occurs in patients with psoriasis and is usually rheumatoid factor (RF) negative.
• In about 15% of Psoriatic Arthritis cases, arthritis develops before the onset of skin lesions.
• Clinical findings in Psoriatic Arthritis include skin psoriasis, nail changes (pitting, onycholysis), and dactylitis ("sausage digits").
• The five patterns of Psoriatic Arthritis are:
  1. Asymmetric Oligoarticular Arthritis: The most common pattern, affecting <4 joints asymmetrically.
  2. Symmetrical Polyarthritis: Mimics RA but is distinguished by RF negativity and DIP joint involvement.
  3. Distal Interphalangeal (DIP) Predominant Arthropathy: Often associated with nail changes.
  4. Predominant Spondyloarthritis: Affects the axial skeleton and must be distinguished from AS.
  5. Destructive (Arthritis Mutilans): The most severe form, leading to a "pencil-in-cup" deformity on x-rays and telescoping of digits.
• Diagnosis of Psoriatic Arthritis is primarily clinical. RF is negative in the majority, and there is no single diagnostic lab test. The CASPAR criteria are used for classification.
• Treatment for Psoriatic Arthritis includes NSAIDs, DMARDs (methotrexate is first-line), and biologics (Anti-TNF, Anti-IL-23, Anti-IL-17).
• Oral steroids are generally not advised in Psoriatic Arthritis as they can cause an exacerbation of skin lesions upon withdrawal.

IV. REACTIVE ARTHRITIS (ReA)

• Reactive Arthritis (ReA) is an acute nonpurulent arthritis that develops 1-4 weeks after an extra-articular infection, where the microorganism does not enter the joint.
• Common infectious triggers for Reactive Arthritis include genitourinary infections (most commonly Chlamydia trachomatis) and gastrointestinal infections (Salmonella, Shigella, Campylobacter, Yersinia).
• The classic triad for Reactive Arthritis (formerly Reiter's Syndrome) is "Arthritis + Conjunctivitis + Urethritis."
• Clinical manifestations of Reactive Arthritis include an acute, asymmetric oligoarthritis (predominantly lower limbs), dactylitis, enthesitis (e.g., heel pain), conjunctivitis, circinate balanitis, and keratoderma blenorrhagica (hyperkeratotic skin lesions on palms/soles).
• Reactive Arthritis is typically self-limiting and resolves in less than 6 weeks.
• Treatment for Reactive Arthritis includes high-dose NSAIDs as first-line therapy. Antibiotics are used if the initial infection is still active. Sulfasalazine may be used for persistent cases (>6 weeks).

HIGH-YIELD COMPARISONS & KEY DISTINCTIONS

• Symmetry & Joint Pattern: Rheumatoid Arthritis is typically a symmetric polyarthritis affecting small joints (MCP, PIP). Spondyloarthropathies (like PsA and ReA) are typically an asymmetric oligoarthritis affecting large, lower-extremity joints.
• Morning Stiffness: In Rheumatoid Arthritis, morning stiffness is prolonged, lasting > 1 hour. In Osteoarthritis (a key differential for joint pain), stiffness is brief, lasting < 30 minutes.
• Hand Joint Involvement: Rheumatoid Arthritis classically affects the MCP and PIP joints, sparing the DIP joints. Psoriatic Arthritis characteristically involves the DIP joints.
• Key Serology Markers: Rheumatoid Factor (RF) and Anti-CCP are markers for RA. HLA-B27 is the key genetic marker for Spondyloarthropathies, especially Ankylosing Spondylitis.
• RA vs. PsA Hand Findings: RA is associated with swan neck and boutonniere deformities. PsA is associated with dactylitis ("sausage digit") and arthritis mutilans with "pencil-in-cup" deformity on x-ray.
• Radiographic Spine Findings: Ankylosing Spondylitis shows symmetric, fine syndesmophytes leading to a "bamboo spine". Axial PsA tends to have asymmetric, bulkier, non-marginal syndesmophytes.
• RA vs. Symmetric PsA: Symmetrical polyarthritis in PsA can mimic RA. Distinguishing features for PsA are a history of psoriasis, nail changes, DIP joint involvement, and negative RF.
• Role of Steroids: Systemic steroids are a cornerstone for rapid control in RA flares. In contrast, oral steroids are generally avoided in Psoriatic Arthritis due to the risk of triggering a psoriasis flare-up.
• Extra-Articular Triggers: Reactive Arthritis is distinctly triggered by a preceding GI or GU infection. No such acute trigger is characteristic of RA or PsA.
• Classic Triad: Reactive Arthritis is associated with the triad of arthritis, conjunctivitis, and urethritis.
• Skin Manifestations: Psoriatic Arthritis is defined by psoriasis (erythematous, scaly plaques). Reactive Arthritis can cause keratoderma blenorrhagica (pustules and crusts on palms/soles).
• Synovial Fluid: RA shows inflammatory fluid (WBC 5k-50k). This must be distinguished from septic arthritis (WBC >50k, positive culture) and Osteoarthritis (non-inflammatory, WBC <2k).
• First-Line Treatment for Arthritis: In RA and PsA, the anchor drug is Methotrexate. In Ankylosing Spondylitis, first-line therapy is NSAIDs, with a strong push towards early use of biologics (Anti-TNF, Anti-IL-17).
• Ankylosing Spondylitis vs. other SpA: AS is defined by its primary and severe involvement of the axial skeleton, leading to spinal fusion. While other SpAs can have axial involvement, it is the defining and central feature of AS.
• Dactylitis vs. Nodules: Dactylitis ("sausage digit") is diffuse swelling of an entire finger or toe and is a hallmark of Psoriatic and Reactive Arthritis. Rheumatoid nodules are firm, subcutaneous lumps that occur over pressure points in seropositive RA.

QA

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CHAPTER 358: RHEUMATOID ARTHRITIS (RA)

I. INTRODUCTION & CLINICAL FEATURES

1. What is Rheumatoid Arthritis? | The most common form of chronic inflammatory arthritis, characterized by systemic polyarthritis.
2. What is the goal in treating Rheumatoid Arthritis? | To diagnose and treat early before irreversible joint damage and functional disability ensue.
3. What is the epidemiology of Rheumatoid Arthritis? | More common in women than men; incidence increases between 25 and 55 years of age.
4. What is a key clinical feature of Rheumatoid Arthritis regarding morning stiffness? | Early morning stiffness lasting more than one hour, which improves with activity.
5. How does Rheumatoid Arthritis typically present? | Symmetrical joint pain and swelling, with a predilection for small joints of hands and feet.
6. What is a frequent hallmark of Rheumatoid Arthritis involving tendons? | Flexor tendon tenosynovitis.
7. What are the possible initial patterns of joint involvement in Rheumatoid Arthritis? | Monoarticular, oligoarticular (≤ 4 joints), or polyarticular (> 5 joints).

II. PATHOGENESIS 8. Which genetic markers are linked to a predisposition for Rheumatoid Arthritis? | MHC class II alleles, particularly HLA-DRB1 and HLA-DR4. 9. Which antibodies are associated with the pathogenesis of Rheumatoid Arthritis? | Antibodies to cyclic citrullinated polypeptides (anti-CCP). 10. What are some environmental risk factors for Rheumatoid Arthritis? | Cigarette smoking and infectious agents like Porphyromonas gingivalis. 11. What is the key cellular process in the pathogenesis of Rheumatoid Arthritis? | CD4+ T-cell activation, which stimulates secretion of proinflammatory mediators. 12. In Rheumatoid Arthritis, what are the effects of TNF-α on bone? | Inhibits bone formation (Wnt pathway) and stimulates bone destruction (RANKL pathway).

III. MANIFESTATIONS 13. What are the chronic hand deformities in Rheumatoid Arthritis? (5) | 1. Swan neck deformity
2. Boutonniere deformity
3. Ulnar deviation
4. MCP joint subluxation
5. Intrinsic muscle atrophy 14. How is a swan neck deformity characterized in Rheumatoid Arthritis? | Hyperextension of the PIP joint and flexion of the DIP joint. 15. How is a Boutonniere deformity characterized in Rheumatoid Arthritis? | Flexion of the PIP joint and hyperextension of the DIP joint. 16. What is ulnar deviation in Rheumatoid Arthritis? | A drift of the fingers toward the ulna at the MCP joints. 17. What deformity can occur at the MCP joint in chronic Rheumatoid Arthritis? | MCP joint subluxation. 18. What is the effect of intrinsic muscle atrophy in Rheumatoid Arthritis? | It worsens and accentuates deformities. 19. When are chronic hand deformities typically seen in Rheumatoid Arthritis? | In long-standing disease, not in the early stages. 20. What ocular extra-articular manifestations are seen in Rheumatoid Arthritis? | Scleritis and secondary Sjogren’s syndrome (sicca syndrome). 21. What vascular extra-articular manifestations are seen in Rheumatoid Arthritis? | Rheumatoid vasculitis, which can manifest as Livedo reticularis. 22. What dermatologic extra-articular manifestation is seen in chronic, seropositive Rheumatoid Arthritis? | Rheumatoid nodules. 23. What pulmonary extra-articular manifestation is seen in Rheumatoid Arthritis? | Interstitial lung disease (ILD), which can be exacerbated by methotrexate.

IV. DIAGNOSIS 24. What criteria are used for the diagnosis of Rheumatoid Arthritis and what score is needed? | 2010 ACR/EULAR Criteria, requiring a score of ≥ 6. 25. Under the 2010 criteria, what are considered "small joints" and "large joints" in Rheumatoid Arthritis? | Small: MCPs, PIPs, MTPs.
Large: Shoulders, elbows, hips, knees, ankles. 26. For arthritis lasting less than 6 weeks, what differential diagnosis for Rheumatoid Arthritis should be considered? | Viral arthritis (e.g., Chikungunya). 27. What is Rheumatoid Factor (RF)? | An autoantibody (commonly IgM) directed against the Fc portion of IgG. 28. What does a high titer of Rheumatoid Factor prognosticate in Rheumatoid Arthritis? | A more severe disease with extra-articular manifestations. 29. How is the sensitivity and specificity of Rheumatoid Factor for Rheumatoid Arthritis? | Sensitive but not specific. 30. What is a key characteristic of Anti-Cyclic Citrullinated Peptide (anti-CCP) antibodies in diagnosing Rheumatoid Arthritis? | More specific for Rheumatoid Arthritis than RF. 31. What does the presence of anti-CCP antibodies often indicate in Rheumatoid Arthritis? | A more aggressive disease with a tendency for bone erosions. 32. What does synovial fluid analysis show in Rheumatoid Arthritis? | An inflammatory pattern with a WBC count of 5,000-50,000/μL, predominantly neutrophils. 33. Is synovial fluid analysis diagnostic for Rheumatoid Arthritis? | No, but it is useful to confirm inflammatory arthritis and rule out other causes. 34. What might plain radiography show in early Rheumatoid Arthritis? | Periarticular osteopenia; erosions are a later finding. 35. Which imaging modality is highly sensitive for detecting early synovitis in Rheumatoid Arthritis? | MRI (Magnetic Resonance Imaging). 36. What is ultrasound useful for detecting in Rheumatoid Arthritis? | Erosions and synovitis.

V. MANAGEMENT 37. What is the primary goal of Rheumatoid Arthritis treatment? | To achieve remission or low disease activity. 38. What are the key treatment principles for Rheumatoid Arthritis? (5) | 1. Early, aggressive treatment
2. Frequent modification of DMARDs
3. Individualization
4. Minimal glucocorticoid use
5. Achieving remission 39. How often should patients with Rheumatoid Arthritis be monitored? | Regularly (e.g., every 3 months) to assess disease activity and screen for side-effects. 40. How are NSAIDs used in Rheumatoid Arthritis management? | As adjunct therapy for symptomatic relief. 41. How are steroids used in Rheumatoid Arthritis management? | For rapid disease control during diagnosis and flares (<7.5 mg/day). 42. What is the drug of choice and anchor drug for Rheumatoid Arthritis? | Methotrexate, dosed once a week with folic acid supplementation. 43. What is a common adverse effect of anti-TNF biologic DMARDs used in Rheumatoid Arthritis? | Reactivation of latent tuberculosis. 44. What are examples of targeted synthetic DMARDs (tsDMARDs) for Rheumatoid Arthritis? | JAK inhibitors such as Tofacitinib and Baricitinib (oral medications).

CHAPTER 362: SPONDYLOARTHRITIS (SpA)

I. SPECTRUM OF SPONDYLOARTHROPATHIES 45. What are Spondyloarthropathies? | A group of inflammatory diseases sharing features like sacroiliitis, enthesitis, and HLA-B27 association. 46. What are the three most common types of Spondyloarthropathy? | Ankylosing Spondylitis, Psoriatic Arthritis, and Reactive Arthritis. 47. How does Spondyloarthropathy typically present, in contrast to Rheumatoid Arthritis? | Asymmetric, oligoarticular inflammatory arthritis, often involving large lower limb joints. 48. What are the key musculoskeletal manifestations of Spondyloarthropathy? | Sacroiliitis, inflammatory spinal lesions, enthesitis, and dactylitis ("sausage digits").

II. ANKYLOSING SPONDYLITIS (AS) 49. What is Ankylosing Spondylitis? | A chronic inflammatory disorder primarily affecting the axial skeleton. 50. What is the typical onset and demographic for Ankylosing Spondylitis? | Begins in the 2nd or 3rd decade, more common in men, strong HLA-B27 association. 51. What is often the earliest manifestation of Ankylosing Spondylitis? | Symmetrical sacroiliitis. 52. What is the radiographic hallmark of advanced Ankylosing Spondylitis? | "Bamboo spine". 53. What is the Schober’s test used to assess for in Ankylosing Spondylitis? | Decreased lumbar spine flexion. 54. What are the key components of treatment for Ankylosing Spondylitis? | Exercise, NSAIDs, Biologics (Anti-TNF, Anti-IL17), and Sulfasalazine. 55. Why is exercise critically important in Ankylosing Spondylitis? | To maintain posture and range of motion. 56. What is the first-line therapy to reduce pain in Ankylosing Spondylitis? | NSAIDs. 57. What are highly effective first-line therapies for Ankylosing Spondylitis besides NSAIDs? | Biologics: Anti-TNF and Anti-IL17 agents. 58. When is sulfasalazine used in Ankylosing Spondylitis? | For peripheral arthritis associated with AS. 59. What is a major complication of advanced Ankylosing Spondylitis? | Spinal fracture.

III. PSORIATIC ARTHRITIS (PsA) 60. What is Psoriatic Arthritis? | An inflammatory musculoskeletal disease in patients with psoriasis, usually RF negative. 61. In what percentage of Psoriatic Arthritis cases does arthritis precede skin lesions? | About 15%. 62. What are the key clinical findings in Psoriatic Arthritis? | Skin psoriasis, nail changes (pitting, onycholysis), and dactylitis ("sausage digits"). 63. What are the five patterns of Psoriatic Arthritis? | 1. Asymmetric Oligoarticular
2. Symmetrical Polyarthritis
3. DIP Predominant
4. Predominant Spondyloarthritis
5. Destructive (Arthritis Mutilans) 64. What is the most common pattern of Psoriatic Arthritis? | Asymmetric Oligoarticular Arthritis. 65. How is the Symmetrical Polyarthritis pattern of Psoriatic Arthritis distinguished from RA? | By RF negativity and DIP joint involvement. 66. The Distal Interphalangeal (DIP) Predominant pattern of Psoriatic Arthritis is often associated with what finding? | Nail changes. 67. The Predominant Spondyloarthritis pattern of Psoriatic Arthritis must be distinguished from what other disease? | Ankylosing Spondylitis. 68. What is the most severe form of Psoriatic Arthritis and its radiographic finding? | Destructive (Arthritis Mutilans), with "pencil-in-cup" deformity. 69. How is Psoriatic Arthritis diagnosed? | Primarily clinical; RF is usually negative, and CASPAR criteria are used. 70. What does the treatment for Psoriatic Arthritis include? | NSAIDs, DMARDs (methotrexate is first-line), and biologics. 71. Why are oral steroids generally not advised in Psoriatic Arthritis? | They can cause an exacerbation of skin lesions upon withdrawal.

IV. REACTIVE ARTHRITIS (ReA) 72. What is Reactive Arthritis? | An acute nonpurulent arthritis developing 1-4 weeks after an extra-articular infection. 73. What are the common infectious triggers for Reactive Arthritis? | Genitourinary (Chlamydia) and gastrointestinal (Salmonella, Shigella, etc.) infections. 74. What is the classic triad for Reactive Arthritis? | "Arthritis + Conjunctivitis + Urethritis." 75. What are the clinical manifestations of Reactive Arthritis? | Acute asymmetric oligoarthritis, dactylitis, enthesitis, conjunctivitis, circinate balanitis, keratoderma blenorrhagica. 76. What is the typical clinical course of Reactive Arthritis? | It is typically self-limiting and resolves in less than 6 weeks. 77. What is the first-line therapy for Reactive Arthritis? | High-dose NSAIDs. Sulfasalazine may be used for persistent cases.

HIGH-YIELD COMPARISONS & KEY DISTINCTIONS

78. Compare the symmetry and joint pattern of Rheumatoid Arthritis vs. Spondyloarthropathies. | RA: Symmetric polyarthritis, small joints.
    SpA: Asymmetric oligoarthritis, large lower-extremity joints.
79. Compare morning stiffness in Rheumatoid Arthritis vs. Osteoarthritis. | RA: Prolonged, > 1 hour.
    Osteoarthritis: Brief, < 30 minutes.
80. Compare hand joint involvement in Rheumatoid Arthritis vs. Psoriatic Arthritis. | RA: MCP and PIP joints, spares DIP.
    PsA: Characteristically involves the DIP joints.
81. What are the key serology markers for Rheumatoid Arthritis vs. Spondyloarthropathies? | RA: Rheumatoid Factor and Anti-CCP.
    SpA: HLA-B27.
82. Compare the hand findings in Rheumatoid Arthritis vs. Psoriatic Arthritis. | RA: Swan neck & boutonniere deformities.
    PsA: Dactylitis & "pencil-in-cup" deformity.
83. Compare radiographic spine findings in Ankylosing Spondylitis vs. axial Psoriatic Arthritis. | AS: Symmetric, fine syndesmophytes ("bamboo spine").
    PsA: Asymmetric, bulkier syndesmophytes.
84. How can symmetric Psoriatic Arthritis be distinguished from Rheumatoid Arthritis? | PsA has history of psoriasis, nail changes, DIP involvement, and is negative for RF.
85. Compare the role of steroids in Rheumatoid Arthritis vs. Psoriatic Arthritis. | RA: Used for rapid control.
    PsA: Generally avoided due to risk of psoriasis flare.
86. What is a key distinction regarding triggers for Reactive Arthritis? | It is distinctly triggered by a preceding GI or GU infection.
87. Which arthritis is associated with the classic triad of arthritis, conjunctivitis, and urethritis? | Reactive Arthritis.
88. Compare the skin manifestations of Psoriatic Arthritis vs. Reactive Arthritis. | PsA: Psoriasis (erythematous, scaly plaques).
    ReA: Keratoderma blenorrhagica (pustules on palms/soles).
89. Compare the synovial fluid findings in Rheumatoid Arthritis vs. septic arthritis and Osteoarthritis. | RA: Inflammatory (WBC 5k-50k).
    Septic: WBC >50k.
    OA: Non-inflammatory (WBC <2k).
90. What is the first-line anchor drug for Rheumatoid Arthritis and Psoriatic Arthritis? | Methotrexate.
91. What is the first-line therapy for Ankylosing Spondylitis? | NSAIDs, with early use of biologics (Anti-TNF, Anti-IL-17).
92. How is Ankylosing Spondylitis primarily defined compared to other Spondyloarthropathies? | By its primary and severe involvement of the axial skeleton, leading to spinal fusion.
93. Differentiate between dactylitis and rheumatoid nodules. | Dactylitis: Diffuse swelling of a whole digit (PsA, ReA).
    Nodules: Firm lumps over pressure points (RA).