A 45-year-old man with a history of hepatitis C develops hematuria and proteinuria. Serum complement (C3) is low. Renal biopsy reveals hypercellularity with double-contour (tram-track) appearance of glomerular basement membranes on PAS/silver stain. Which immunofluorescence pattern is expected?

• A Granular deposits of IgG and C3 along GBM and mesangium (immune-complex MPGN) ✓
• B Linear IgG along GBM (anti-GBM disease)
• C Dominant IgA deposition in mesangium
• D Pauci-immune pattern (no significant Ig deposition)

Explanation

The tram-track GBM duplication is the hallmark of membranoproliferative glomerulonephritis (MPGN). HCV-associated MPGN is immune-complex mediated (type I/II MPGN) from cryoglobulin or HCV antigen-antibody complexes depositing in glomeruli, producing granular IgG and C3 on IF with low serum C3. Linear IgG characterizes anti-GBM disease (Goodpasture). Dominant IgA mesangial deposits define IgA nephropathy. Pauci-immune is seen in ANCA vasculitis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.