A 10-year-old boy presents with nephrotic syndrome. Light microscopy of renal biopsy shows diffuse mesangial hypercellularity. Immunofluorescence shows dominant mesangial C1q deposits. Electron microscopy shows mesangial electron-dense deposits and diffuse foot process effacement. The most likely diagnosis is:
- A Minimal change disease
- B IgA nephropathy
- C C1q nephropathy ✓
- D Lupus nephritis class II
Correct answer: C. C1q nephropathy
Explanation
B1q nephropathy is defined by dominant or co-dominant B1q deposits in the mesangium on immunofluorescence with mesangial electron-dense deposits. It presents with nephrotic syndrome and can resemble minimal change disease or FSGS on light microscopy. Minimal change disease shows no immune deposits. IgA nephropathy shows dominant IgA, not B1q. Lupus nephritis class II would show mesangial deposits but with full-house pattern, not isolated B1q dominance.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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