A 38-year-old man with adult-onset asthma now poorly controlled, chronic sinusitis, and a peripheral eosinophil count of 6,800 per microlitre develops palpable purpura and mononeuritis multiplex. Chest imaging shows fleeting migratory infiltrates without cavitation. Which finding best supports the diagnosis?
- A Positive c-ANCA with anti-proteinase 3
- B Positive p-ANCA with anti-myeloperoxidase ✓
- C Positive anti-glomerular basement membrane antibody
- D Positive anti-phospholipase A2 receptor antibody
Correct answer: B. Positive p-ANCA with anti-myeloperoxidase
Explanation
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss) presents as asthma plus eosinophilia plus small vessel vasculitis, often with neuropathy and transient pulmonary infiltrates. Roughly 40 percent of patients have ANCA, usually p-ANCA against myeloperoxidase. GPA is defined by c-ANCA against proteinase 3 with cavitating nodules and granulomatous inflammation, which this patient lacks. Anti-GBM disease causes rapidly progressive glomerulonephritis with pulmonary haemorrhage, and anti-PLA2R belongs to membranous nephropathy.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.