Electron microscopy of a renal biopsy from a 5-year-old with nephrotic syndrome shows diffuse effacement of podocyte foot processes but NO immune deposits. Light microscopy shows normal glomeruli. Immunofluorescence is negative. The pathogenesis is best explained by:

• A Linear IgG deposition against GBM
• B Immune complex deposition from streptococcal antigens
• C Mutation in nephrin gene (NPHS1) causing congenital nephrotic syndrome
• D Circulating permeability factors (possibly CLCF1/cardiotrophin-like cytokine factor 1) causing podocyte injury ✓

Explanation

The biopsy findings describe minimal change disease (MCD), the most common cause of nephrotic syndrome in children. The pathogenesis involves circulating permeability factors (T cell-derived; recent evidence implicates CLCF1/cardiotrophin-like cytokine factor 1 and hemopexin) that cause podocyte injury and foot process effacement without immune deposits. Linear GBM IgG deposition is seen in anti-GBM disease; immune complexes characterize post-streptococcal GN; nephrin mutations cause Finnish congenital nephrotic syndrome which presents at birth.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.