A 70-year-old man presents with acute nephritic syndrome: hematuria, proteinuria, hypertension. Serum ANCA (PR3-ANCA/c-ANCA) is positive. Renal biopsy shows focal necrotizing glomerulonephritis with cellular crescents. IF shows NO immune deposits ('pauci-immune'). The diagnosis is:

• A Anti-GBM disease (Goodpasture syndrome)
• B ANCA-associated pauci-immune crescentic glomerulonephritis ✓
• C Post-streptococcal glomerulonephritis
• D IgA nephropathy with crescents

Explanation

Pauci-immune crescentic GN is defined by crescentic nephritis with absent or scant immune deposits on IF, distinguishing it from anti-GBM disease (linear IgG) and immune-complex GN (granular deposits). PR3-ANCA (c-ANCA) positivity points to GPA (granulomatosis with polyangiitis); MPO-ANCA (p-ANCA) is more common in microscopic polyangiitis. The pauci-immune pattern reflects T cell-mediated, neutrophil-driven vascular injury rather than immune complex deposition.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.