A clinicopathologic study of focal segmental glomerulosclerosis: comparison between nephrotic and non-nephrotic focal segmental glomerulosclerosis.

Seven out of 16 patients with primary focal segmental glomerulosclerosis (FGS) did not showed the nephrotic syndrome throughout their clinical courses, and then patients with FGS could be divided into the two groups, nephrotic FGS group (NS-G) and non-nephrotic one (NO-G). The clinicopathologic findings of NS-G and NO-G were compared retrospectively to define the pathogenesis of the glomerular disease in FGS. No significant differences were found between the groups except for proteinuria and serum total protein or albumin, and it was impossible to distinguish the two groups only histologically. In addition, electron microscopic study revealed that the glomerular epithelial cell was altered more than the endothelial and mesangial cells in both groups, resulting in vacuolization, foot process fusion, and detachment, and the striking fact that the glomerular epithelial vacuoles consisted mainly of the dilated rough endoplasmic reticulums (RERs). The speculation is drawn that in FGS the glomerular epithelial cell is firstly damaged by unknown factor(s), manifested functionally proteinuria and/or hematuria, morphologically dilatation of RER, foot process fusion, detachment, and eventually segmental sclerosis and hyalinosis.