Comparison of Glomerular Size between Focal Segmental Glomerulosclerosis and Minimal Lesion in Children

ABSTRACT

The pathogenetic mechanism of focal segmental glomerulosclerosis (FSGS) is not known. Some authors suggest glomerular hypertrophy may precede the development of FSGS in patients with minimal lesion. It was recently reported that the size of nonsclerotic glomeruli in adults with FSGS is significantly larger than that of cases with minimal lesion. It is not clear whether glomerular hypertrophy observed in adults with FSGS is also seen in children with FSGS. Thus, we have analyzed 37 renal biopsies from children with FSGS by morphometry and the data were compared with 37 renal biopsies from age- and sex-matched patients with minimal lesion. The number of glomeruli submitted for morphometric analysis was 22.6+/-14.2 in cases with FSGS and 30.9+/-11.4 in cases with minimal lesion. Mean glomerular volume (MGV) in FSGS group was significantly larger than that of minimal lesion [(13.1+/-3.9) x10(5) microm3 vs. (10.1+/-1.9) x10(5) microm3, p<0.001]. The relative interstitial volume of renal cortex in patients with FSGS was significantly larger than that of minimal lesion [(0.106+/-0.051) microm3/microm3 vs. (0.029+/-0.012) microm3/microm3, p<0.0001]. In FSGS, the percentage of glomeruli with FSGS was significantly correlated with relative interstitial volume of renal cortex (r=0.79, p<0.0001). As is the case for adult FSGS, MGV of children with FSGS is significantly larger than that of minimal lesion. Thus, the presence of glomerular hypertrophy observed in biopsies with minimal lesion nephropathy seems to be an indication that the coexistent FSGS lesions are undetected due to sampling problems.