A 10-year-old boy with nephrotic syndrome undergoes renal biopsy after steroid resistance. LM shows mesangial hypercellularity and segmental sclerosis. EM shows diffuse podocyte foot process effacement without immune deposits. IHC is positive for IgM and C3 in sclerotic segments. This pattern most likely represents:

• A IgA nephropathy
• B Minimal change disease with secondary sclerosis
• C Membranoproliferative glomerulonephritis type I
• D Focal segmental glomerulosclerosis (FSGS) — not otherwise specified variant ✓

Explanation

The FSGS NOS (not otherwise specified, formerly 'classic') variant shows segmental sclerosis with hyalinosis, IgM and C3 trapping in sclerotic areas (non-specific 'trapping'), and diffuse foot process effacement on EM — distinguishing it from immune-complex mediated diseases where there are organized subendothelial or mesangial deposits. FSGS is a leading cause of steroid-resistant nephrotic syndrome in children and adults. The absence of organized immune deposits excludes IgA nephropathy and MPGN.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.