A 32-year-old woman with a 6-year history of severe asthma and allergic rhinitis presents with mononeuritis multiplex and a peripheral eosinophil count of 9,000 per cubic millimeter. Chest imaging shows fleeting infiltrates. Biopsy of an involved vessel shows necrotizing vasculitis with prominent eosinophilic infiltration and extravascular granulomas. Which additional laboratory finding is most characteristic of this condition?
- A Anti-proteinase 3 cytoplasmic ANCA (c-ANCA) in nearly all patients
- B Anti-myeloperoxidase perinuclear ANCA (p-ANCA) in a subset of patients ✓
- C Consistently positive hepatitis B surface antigen
- D Markedly elevated serum cryoglobulins
Correct answer: B. Anti-myeloperoxidase perinuclear ANCA (p-ANCA) in a subset of patients
Explanation
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss) is defined by the triad of asthma, marked blood and tissue eosinophilia, and necrotizing vasculitis with extravascular granulomas. Anti-MPO p-ANCA positivity occurs in a subset and correlates with a vasculitic phenotype. c-ANCA against proteinase 3 points toward granulomatosis with polyangiitis, hepatitis B is linked to classical polyarteritis nodosa, and cryoglobulinemia accompanies mixed cryoglobulinemic vasculitis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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