A 46-year-old man presents with nephrotic-range proteinuria, hypoalbuminaemia, and oedema. Kidney biopsy shows diffuse thickening of capillary walls with granular IgG and C3 along the outer aspect of the glomerular basement membrane. Serum assay for a phospholipase A2 receptor antibody is strongly positive. This antibody status indicates which of the following?
- A Secondary membranous nephropathy related to malignancy
- B Lupus nephritis class V masquerading as primary disease
- C Primary idiopathic membranous nephropathy with an autoimmune basis ✓
- D Membranous nephropathy induced by penicillamine exposure
Explanation
Anti-PLA2R antibodies are found in roughly 70 to 80 percent of cases of primary idiopathic membranous nephropathy and target the PLA2R expressed on podocytes, confirming an autoimmune mechanism. Their presence argues against secondary causes such as solid malignancy, lupus class V, and drugs like penicillamine, gold, or NSAIDs, in which the antibody is typically absent. Titres correlate with disease activity and can guide monitoring, and persistence predicts relapse after therapy. Subepithelial deposits with spike formation on silver stain complete the histological picture.
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.