USMLE/COMLEX 3 - Small Vessel Vasculitis

Here are key facts for USMLE Step 3 & COMLEX-USA Level 3 from the Small Vessel Vasculitis tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. Small vessel vasculitides cause blood vessel inflammation, leading to ischemia, necrosis, and multiorgan dysfunction. 2. Common systemic symptoms: fever, weight loss, fatigue, arthralgias, and skin manifestations like palpable purpura. 3. Initial treatment for most forms is high-dose corticosteroids, with escalation to immunosuppressants for organ-threatening disease. 4. Granulomatosis with polyangiitis (GPA):

• Classic triad: Upper respiratory, lower respiratory, and renal involvement.
• ENT symptoms: sinusitis, otitis media, nasal septal perforation (saddle-nose deformity).
• Pulmonary: cough, hemoptysis, nodular cavitary lesions on imaging.
• Renal: rapidly progressive glomerulonephritis (RPGN).
• Skin: palpable purpura, ulcers.
• Laboratory: c-ANCA positive (anti-proteinase 3).
• Treatment: corticosteroids plus rituximab or cyclophosphamide.

5. Eosinophilic granulomatosis with polyangiitis (EGPA):

• Triad: Asthma, eosinophilia, and vasculitis.
• Cardiac involvement (e.g., myocarditis) is a leading cause of death.
• Peripheral neuropathy (mononeuritis multiplex).
• p-ANCA positive (anti-MPO).
• Treatment: corticosteroids alone for mild disease; corticosteroids plus cyclophosphamide or mepolizumab for severe disease.

6. Microscopic polyangiitis (MPA):

• Rapidly progressive glomerulonephritis and palpable purpura.
• Pulmonary involvement: alveolar hemorrhage possible.
• p-ANCA positive.
• Treatment: corticosteroids plus rituximab or cyclophosphamide.

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1. IgA Vasculitis (Henoch-Schönlein Purpura):

• Common in children, can occur in adults.
• Triad:
• Palpable purpura (typically on lower extremities).
• Arthralgias.
• Abdominal pain, GI bleeding.
• Renal involvement (hematuria, IgA nephropathy).
• Preceded by upper respiratory infection.
• Diagnosis is clinical; confirmed by skin biopsy (IgA deposition) if uncertain.
• Management: Supportive for mild disease; corticosteroids for severe renal, GI, or joint involvement.

2. Cryoglobulinemia:

• Systemic immune-complex vasculitis associated with Hepatitis C.
• Triad:
• Palpable purpura.
• Arthralgia.
• Glomerulonephritis.
• Labs:
• Positive cryoglobulins.
• Low complement (especially C4).
• Treatment: Treat underlying HCV infection with antivirals plus immunosuppressive therapy if severe.

3. SLE and Rheumatoid Arthritis Vasculitis:

• Secondary vasculitis can occur in longstanding disease.
• Monitor for skin ulcers, nephritis, neurologic symptoms.

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1. GPA and MPA:

• Induction: High-dose corticosteroids plus rituximab or cyclophosphamide.
• Maintenance: Azathioprine, methotrexate, or rituximab.

2. EGPA:

• Mild (asthma only): corticosteroids alone.
• Severe (cardiac, renal, mononeuritis multiplex): corticosteroids plus cyclophosphamide or IL-5 inhibitor (mepolizumab).

3. Cryoglobulinemia:

• Start with antiviral therapy if due to Hepatitis C.
• Use corticosteroids if severe or life-threatening disease.

4. IgA Vasculitis:

• Supportive in most pediatric cases.
• Adults with severe renal disease: corticosteroids; monitor renal function closely.

5. GPA:

• Pulmonary hemorrhage.
• End-stage renal disease.

6. EGPA:

• Heart failure from eosinophilic myocarditis.

7. MPA:

• Pulmonary-renal syndrome (hemoptysis and renal failure).

8. Cryoglobulinemia:

• Chronic kidney disease, neuropathy.

9. IgA Vasculitis:

• Long-term renal impairment in adults.

10. ANCA Testing:

• c-ANCA for GPA.
• p-ANCA for MPA and EGPA.

11. Biopsy when possible to confirm diagnosis and rule out infection or malignancy mimicking vasculitis.