Which ANCA pattern and target antigen is most characteristically associated with granulomatosis with polyangiitis (GPA, formerly Wegener's)?

• A p-ANCA pattern; anti-MPO (myeloperoxidase) antibodies
• B c-ANCA pattern; anti-MPO antibodies
• C p-ANCA pattern; anti-elastase antibodies
• D c-ANCA pattern; anti-PR3 (proteinase 3) antibodies ✓

Explanation

Granulomatosis with polyangiitis classically shows c-ANCA (cytoplasmic) pattern on immunofluorescence with specificity for proteinase-3 (PR3-ANCA), present in ~90% of active generalised disease. Microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis (EGPA) more commonly show p-ANCA with anti-MPO specificity. Anti-elastase p-ANCA is seen in drug-induced vasculitis, not GPA.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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