3-DIMENSIONAL ANALYSIS OF GLOMERULAR MORPHOLOGY IN PATIENTS WITH SUBTOTAL NEPHRECTOMY

Previous studies documented that single section examination of kidney tissue underestimates glomerulosclerosis and that three-dimensional ex amination of glomerular morphology improves recognition of the inciden ce and distribution of sclerotic changes within the glomerular capilla ry tuft. We have adopted this technique to evaluate the true frequency and the spatial extent of glomerulosclerosis in patients who were sub jected to extensive renal mass reduction. We re-evaluated four kidney biopsies of patients with a solitary kidney who had undergone partial nephrectomy for renal-cell carcinoma. Histopathological examination ai med at detection of glomerular sclerotic lesions was performed on seri al sections (from 75 to 93 serial sections for each biopsy, 3 mu m thi ck) together with three-dimensional morphometric analysis of glomerula r tuft and sclerotic areas using a computer-based image processing sys tem. Results were compared with observations based on more conventiona l single section evaluation of the same biopsies. Among 65 glomeruli e xamined by three-dimensional morphometric analysis, only 8% were norma l, 42% revealed segmental sclerosis and 51% global sclerosis. These re sults confirmed that single section evaluation grossly overestimates t he number of normal glomeruli (37% vs. 8%, respectively), since the ma jority of glomeruli classified as normal are indeed affected by sclero tic changes in areas typically out of the section plane. The three-dim ensional distribution of sclerosis is characterized by the appearance of multi-focal areas affecting a small capillary tuft volume (<10%/) w hich ultimately propagate to the entire capillary tuft. Despite the ma intenance of renal function, at the time of biopsy in patients with ex tensive ablation of renal mass, the incidence of glomerulosclerosis af fects almost the entire glomerular population. These data suggest scle rotic lesions initially arise as multifocal lesions within the capilla ry tuft, and eventually propagate to global sclerosis.