Is Vacuolization of Podocytes and Glomerular Endothelial Cells of Prognostic Value with Respect to FSGS?

Chair and Department of Clinical Pathomorphology,
Department of Children's Diseases,
Department of Informatics and Statistics, K. Marcinkowski University of Medical Sciences, Poznan

Abstract

Focal segmental glomerulosclerosis (FSGS) poses a major problem both from the clinical and pathomorphological viewpoint. The diagnosis of FSGS in its early stage is vital mainly because of rapidly developing therapeutic modalities. In the literature various changes are discussed which may be of prognostic value (may predict the development of FSGS). One of these changes is vacuolization, mainly of podocytes and less frequently of endothelial cells.

The purpose of the present study was to analyse biopsy specimens to find out to what extent vacuolization of podocytes and endothelial cells is associated with FSGS. We compared vacuolization in minimal change disease (MCD), mesangial glomerulonephritis (GNMES) and FSGS. A similar analysis was made also with respect to those cases of MCD and GNMES, in which electron microscopy suggested an early stage of FSGS. In each group electron micrographs obtained from 15 children were analysed. Electron micrographs (12 - 15 on average) were obtained most frequently from 3 glomeruli. Each electron micrograph contained 90 - 100 podocytes. Based upon the same electron micrograph we counted capillary lumina and defined the percentage of those which contained vacuolized endothelia (we counted the capillary lumina, and not the cells, because it is most frequently impossible to identify the border of vacuolized endothelial cells). The number of capillary cross-sections was 60 on average. The results of the analysis were compared with the clinical data. This comparison did not confirm the hypothesis of other investigators that vacuolization is of a prognostic value.

Additionally we evaluated the character of vacuoles. Within podocytes the vacuoles were varying in shape. Surrounded by a single membranous layer most frequently they contained material corresponding to proteins or proteoglycans, rarely to lipids. Sometimes the vacuoles were autophagosomal, occasionally they consisted of the dilated rough endoplasmic reticulum. Vacuole-like changes within the capillary lumina were related to the swelling of endothelial cytoplasm or mesangial processes. The reasons for a discrepancy between our results and those reported by other investigators necessitate further studies.

Address for correspondence and reprint requests to:
Prof. W. Salwa-Zurawska M. D.,
Department of Clinical Pathomorphology,
Przybyszewskiego 49, 60-355 Poznan.