A renal biopsy from a 50-year-old with nephrotic syndrome shows thickened GBM and 'spike and dome' pattern on silver stain, with granular IgG and PLA2R deposits on immunofluorescence. Electron microscopy shows subepithelial deposits. Anti-PLA2R antibodies are positive. This patient's membranous nephropathy is classified as:

• A Secondary membranous nephropathy (class V lupus nephritis)
• B Drug-induced membranous nephropathy
• C THSD7A-associated membranous nephropathy
• D Primary (idiopathic) membranous nephropathy due to anti-PLA2R autoantibodies ✓

Explanation

Anti-phospholipase A2 receptor (PLA2R) antibodies, directed against the PLA2R on the podocyte surface, are present in approximately 70–80% of cases of primary (idiopathic) membranous nephropathy and not in secondary forms. The 'spike and dome' appearance on silver stain reflects projections of GBM material between subepithelial immune deposits. THSD7A (thrombospondin type-1 domain-containing 7A) is the target in another ~5% of primary MN cases. Lupus nephritis class V shows full-house IF pattern with IgG, IgM, IgA, C3, and C1q.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.