IgA nephropathy (Berger disease) is the most common primary glomerulonephritis worldwide. The pathognomonic immunofluorescence finding is:

• A Linear IgG along the glomerular basement membrane
• B Granular IgA deposits predominantly in the mesangium ✓
• C Subepithelial granular IgG and C3 deposits ('spike and dome')
• D C3-only deposits along capillary walls without immunoglobulin

Explanation

IgA nephropathy is defined by predominant or codominant mesangial IgA deposits on immunofluorescence — this is the diagnostic criterion. The current Oxford (MEST-C) classification scores mesangial hypercellularity (M), endocapillary proliferation (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T), and crescents (C) for prognosis. Linear IgG is characteristic of anti-GBM disease (Goodpasture); subepithelial IgG/C3 is membranous nephropathy; C3-only deposits suggest C3 glomerulopathy.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.