A 30-year-old asthmatic develops recurrent sinusitis, peripheral neuropathy, and a peripheral blood eosinophil count of 4500 cells/microliter. Biopsy of a skin nodule shows necrotizing granulomas and eosinophilic infiltration of a small artery. Which antineutrophil cytoplasmic antibody specificity is classically associated?

• A Anti-proteinase 3 (c-ANCA)
• B Anti-centromere antibody
• C Anti-glomerular basement membrane antibody
• D Anti-myeloperoxidase (p-ANCA) ✓

Explanation

This is eosinophilic granulomatosis with polyangiitis (Churg-Strauss), defined by asthma, allergic rhinitis/sinusitis, marked eosinophilia, and necrotizing granulomatous vasculitis with abundant eosinophils. Anti-MPO p-ANCA is present in roughly half of cases and supports the diagnosis. Anti-PR3 c-ANCA points instead toward granulomatosis with polyangiitis, where upper airway necrotizing granulomas occur without asthma or eosinophilia.

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.