ANCA-associated vasculitides (AAV) include granulomatosis with polyangiitis (GPA), eosinophilic GPA (EGPA), and microscopic polyangiitis (MPA). The predominant ANCA target antigen and histological features distinguish these conditions. Which pairing is CORRECT?
- A GPA — p-ANCA (anti-MPO); necrotizing granulomatous inflammation of upper and lower respiratory tract with pauci-immune crescentic GN
- B MPA — c-ANCA (anti-PR3); granulomatous vasculitis without necrotizing granulomas
- C GPA — c-ANCA (anti-PR3); necrotizing granulomatous inflammation of upper/lower respiratory tract + pauci-immune crescentic GN; EGPA — p-ANCA (anti-MPO); eosinophilic tissue infiltration with extravascular granulomas and asthma ✓
- D EGPA — c-ANCA (anti-PR3); granulomatous vasculitis with eosinophilia and IgE elevation
Explanation
The correct ANCA associations: GPA (formerly Wegener's) — c-ANCA (cytoplasmic ANCA) pattern, anti-PR3 (proteinase-3) specificity in ~75–90%; histology shows necrotizing granulomatous inflammation (upper respiratory — sinuses, nasal septum; lower respiratory — lungs) + pauci-immune crescentic glomerulonephritis. EGPA (formerly Churg-Strauss) — p-ANCA (perinuclear pattern), anti-MPO in ~40–70%; histology shows eosinophilic tissue infiltration, extravascular necrotizing granulomas with eosinophils, and asthma with peripheral eosinophilia. MPA — p-ANCA (anti-MPO) in ~60–70%; necrotizing vasculitis without granulomas, pauci-immune crescentic GN (identical to GPA renally but no granulomas). Option A incorrectly assigns p-ANCA to GPA.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.