A 62-year-old man presents with rapidly progressive glomerulonephritis, rising creatinine, and hemoptysis. Immunofluorescence of the renal biopsy shows no significant staining for immunoglobulin or complement. The most likely category of RPGN is:

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

Explanation

Pauci-immune (type III) RPGN is the most common form overall and in older adults, defined by few or no immune deposits on immunofluorescence and association with ANCA (MPO or PR3). Type I would show linear IgG along the GBM, and type II would show granular deposits. The absence of any immunoglobulin staining excludes both. Hemoptysis occurs in ANCA-associated vasculitis (microscopic polyangiitis, GPA) just as it does in Goodpasture syndrome, so the IF pattern decides.

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.