A 60-year-old man with hepatitis C virus infection presents with palpable purpura on lower extremities, arthralgias, and weakness. Serum cryoglobulins are positive. Complement C4 is markedly low. Renal biopsy shows membranoproliferative glomerulonephritis. What is the underlying pathophysiology driving this vasculitis?

• A Immune complex deposition ✓
• B ANCA-mediated neutrophil activation
• C Anti-GBM antibody deposition
• D Complement deficiency

Explanation

Mixed cryoglobulinemia type II and III associated with hepatitis C results from immune complex deposition of cryoglobulins (IgM rheumatoid factor and HCV antigen complexes) in small vessels. This causes leukocytoclastic vasculitis, palpable purpura, arthralgias, and MPGN. Low C4 is characteristic. ANCA-associated vasculitis and anti-GBM disease have different mechanisms.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.