Diagnostic and prognostic significance of glomerular epithelial cell vacuolization and podocyte effacement in children with minimal lesion nephrotic syndrome and focal segmental glomerulosclerosis: an ultrastructural study.

Children with minimal lesion nephrotic syndrome (MLNS) may later develop focal segmental glomerulosclerosis (FSGS). It has been suggested that a low percentage of epithelial podocyte effacement (EPE) and a high degree of epithelial cell vacuolization (ECV) in nonsclerotic glomeruli presage FSGS, and that extensive epithelial cell vacuolization in biopsies clearly showing FSGS predicts a poor clinical outcome. To investigate these contentions, we examined by electron microscopy three glomeruli from each of the first biopsies of 30 patients. Ten patients (group 1) had MLNS, 10 (group 2) had FSGS, and 10 (group 3) had MLNS which progressed to FSGS. Clinical data was obtained by retrospective review of medical records. The percent of epithelial podocyte effacement was calculated by computerized linear tracing and epithelial cell vacuolization was scored semiquantitatively from 0-3. (formula; see text) The percent podocyte effacement in each group was the same and does not distinguish MLNS from FSGS. Group 2 had more extensive epithelial cell vacuolization than group 1 (p less than 0.04) and the same as group 3 (p = 0.16). The combined ECV score for groups 2 and 3, however, was significantly greater than for group 1 (p less than 0.025) suggesting that epithelial cell vacuolization may indeed be a marker of FSGS. The extent of epithelial cell vacuolization did not correlate with creatinine clearance at latest follow-up, and thus does not predict clinical outcome.