A 62-year-old man develops malaise, oliguria and cola-colored urine over three weeks. Creatinine rises from 1.0 to 6.5 mg/dL. Urinalysis shows dysmorphic red cells and red cell casts. Renal biopsy shows circumferential cellular crescents in more than 60 percent of glomeruli. Immunofluorescence shows little or no staining for IgG, IgA, C3 or fibrin. Which category of rapidly progressive glomerulonephritis does this represent?

• A Type III, pauci-immune ANCA associated ✓
• B Type II, immune complex mediated
• C Type I, anti-GBM antibody mediated
• D Type IV, dual anti-GBM and ANCA positive

Explanation

Pauci-immune crescentic GN is defined by few or no immune deposits on immunofluorescence despite severe necrotizing and crescentic injury, and it accounts for about 60 percent of RPGN cases. It is linked to circulating ANCA, usually MPO-ANCA in this age group, and includes microscopic polyangiitis and granulomatosis with polyangiitis. Type I would show linear IgG along the GBM, and type II would show granular deposits, neither of which is present here.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.