A 45-year-old woman presents with AKI (creatinine rising from 0.9 to 4.2 mg/dL over 4 weeks), haemoptysis, haematuria, and red cell casts. cANCA (anti-PR3) is strongly positive. Renal biopsy is most likely to show:

• A Membranous nephropathy with spike and dome pattern
• B Linear IgG deposits along the GBM (anti-GBM disease)
• C Mesangial IgA deposits with mesangial hypercellularity
• D Pauci-immune crescentic glomerulonephritis with fibrocellular crescents ✓

Explanation

ANCA-associated vasculitis (GPA, MPA) causes pauci-immune crescentic GN — so called because immunofluorescence shows little or no immunoglobulin deposition (distinguishing it from anti-GBM and immune-complex GN). Light microscopy reveals crescents with fibrin and cellular proliferation. Haemoptysis + haematuria + cANCA positivity = pulmonary-renal syndrome due to GPA. Linear IgG deposits are the hallmark of Goodpasture's disease (anti-GBM antibodies). Mesangial IgA deposits define IgA nephropathy.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.