A 30-year-old woman develops nephrotic syndrome. Renal biopsy light microscopy shows diffuse basement membrane thickening without increase in cellularity. Silver stain shows a 'spike and dome' pattern along the capillary walls. Immunofluorescence shows granular IgG and C3 deposition along GBM. Electron microscopy shows subepithelial electron-dense deposits. What is the diagnosis?
- A Membranoproliferative glomerulonephritis (MPGN) type I
- B Membranous nephropathy ✓
- C Focal segmental glomerulosclerosis
- D Lupus nephritis class V
Explanation
Membranous nephropathy (MN) is characterized by diffuse thickening of the glomerular basement membrane without hypercellularity on light microscopy, a 'spike and dome' pattern on silver stain (spikes = GBM projecting between subepithelial deposits), granular IgG/C3 on immunofluorescence, and subepithelial immune deposits on EM. The most common primary form is caused by anti-PLA2R (phospholipase A2 receptor) antibodies. MPGN shows mesangial and endothelial proliferation with a 'tram-track' pattern; FSGS shows segmental sclerosis with foot process effacement but no immune deposits.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.