Recurrent nephrotic syndrome in renal allografts.

We describe the clinicopathologic course of two patients with recurrent focal segmental glomerular sclerosis (FSGS). In both patients, FSGS was initially demonstrated during the evaluation of proteinuria. After progressing to end-stage renal disease, each patient received a living-related renal transplant. Shortly after transplantation, proteinuria recurred in both patients, progressing to the nephrotic syndrome. Serial renal biopsies were obtained from each patient. These initially demonstrated focal segmental epithelial proliferation (the "cellular lesion"), but focal segmental scars were observed in subsequent biopsies. None of the biopsies demonstrated immunoglobulin, complement deposition, or diffuse epithelial cell foot process fusion. These findings suggest that the scarring lesion in recurrent FSGS may be the result of a primary process involving damage to a limited number of visceral epithelial cells.