A renal biopsy from a patient with nephrotic syndrome shows thickening of the GBM with silver stain 'spike and dome' pattern on EM showing subepithelial deposits. Serology reveals anti-PLA2R antibodies. The most appropriate first-line diagnosis is:
- A Secondary membranous nephropathy due to SLE
- B Primary (idiopathic) membranous nephropathy ✓
- C Diabetic nephropathy
- D Amyloidosis
Correct answer: B. Primary (idiopathic) membranous nephropathy
Explanation
Anti-PLA2R (anti-phospholipase A2 receptor) antibodies are detected in approximately 70-80% of primary (idiopathic) membranous nephropathy cases, and their presence essentially confirms primary etiology. Subepithelial immune deposits with spike-and-dome pattern on silver stain/EM is the hallmark of membranous nephropathy. Secondary causes (SLE, drugs, infections) are anti-PLA2R negative. Diabetic nephropathy shows GBM thickening and Kimmelstiel-Wilson nodules without subepithelial 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.