A 58-year-old man presents with chronic destructive sinusitis, hemoptysis, and rapidly progressive glomerulonephritis. c-ANCA (PR3-ANCA) is positive. Renal biopsy shows pauci-immune necrotizing glomerulonephritis. What is the characteristic histopathological hallmark that distinguishes this condition from microscopic polyangiitis?

• A Eosinophilic infiltration of vessel walls
• B Pauci-immune necrotizing glomerulonephritis
• C Fibrinoid necrosis of small vessels
• D Necrotizing granulomatous inflammation ✓

Explanation

Granulomatosis with polyangiitis (GPA) is distinguished by necrotizing granulomatous inflammation of the upper and lower respiratory tract, along with glomerulonephritis. Microscopic polyangiitis lacks granulomas. Pauci-immune GN and fibrinoid necrosis are common to both ANCA-associated vasculitides. Eosinophilic infiltration is seen in eosinophilic GPA (Churg-Strauss).

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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