A 10-year-old boy presents with periorbital oedema, cola-coloured urine, and hypertension 2 weeks after a skin infection. Serum creatinine is 1.8 mg/dL, C3 is low, C4 is normal, and ASO titre is elevated. Which pathological finding is most characteristic on renal biopsy?

• A Crescent formation in >50% of glomeruli
• B Mesangial IgA deposits on immunofluorescence
• C Subepithelial 'humps' on electron microscopy ✓
• D Thickened glomerular basement membrane with 'spikes'

Explanation

Post-streptococcal glomerulonephritis shows subepithelial electron-dense 'humps' on EM, the hallmark finding. A3 is low with normal A4 (alternative pathway activation). Latency is 1-3 weeks after infection. Option B describes IgA nephropathy (synpharyngitic, normal complement). Option A describes RPGN. Option D describes membranous nephropathy.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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