A 48-year-old man has proteinuria of 6 g/day. Renal biopsy shows subepithelial immune deposits with a spike pattern on silver stain. Serum testing is positive for antibodies against phospholipase A2 receptor (PLA2R). What does this result establish?

• A Primary (idiopathic) membranous nephropathy ✓
• B Secondary membranous nephropathy due to an occult malignancy
• C Membranous lupus nephritis requiring immunosuppression
• D Hepatitis B virus associated membranous nephropathy

Explanation

PLA2R is an antigen on podocyte membranes; circulating anti-PLA2R antibodies are found in about 70 to 80 percent of patients with primary membranous nephropathy and are rarely present when a secondary cause exists. B positive titre therefore supports idiopathic disease. In secondary membranous nephropathy from lupus, hepatitis A or malignancy, other antigens such as PLA2R-negative deposits, exogenous antigens or tumor-related mechanisms drive the deposits, so positivity argues strongly against those options.

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.