A 45-year-old man presents with nephrotic syndrome. Renal biopsy shows mesangial proliferation with increased mesangial matrix and segmental sclerosis. Immunofluorescence shows dominant C3 deposits in the mesangium with no significant immunoglobulin deposits. Electron microscopy shows mesangial and subendothelial deposits. The most likely diagnosis is:

• A C3 glomerulopathy (C3GN) ✓
• B Membranoproliferative glomerulonephritis type I
• C Lupus nephritis class III
• D IgA nephropathy

Explanation

C3 glomerulopathy is defined by C3-dominant glomerular deposits with absent or minimal immunoglobulin on immunofluorescence, differentiating it from immune-complex-mediated diseases. MPGN type I shows both C3 and immunoglobulins. Lupus nephritis shows full-house staining. IgA nephropathy shows dominant IgA deposits. The current classification reclassifies former MPGN type II and some MPGN type I cases as C3 glomerulopathy.

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.