Renal oncocytoma. A clinicopathologic study.

Seven cases of renal oncocytomas are described. Two cases were from recent surgical and autopsy material seen within a period of ten months. Four cases were reclassified as renal oncocytomas from a 20 year review of 63 renal cell carcinomas removed operatively. One case was identified from a nine year review of 31 renal cell carcinomas coded in our autopsy files. All patients were males; mean age was 69 years. The smallest tumor measuring 0.3 X 0.3 X 0.3 cm represents the smallest renal oncocytoma reported. The largest tumor weighed 2350 g. It is the largest renal oncocytoma so far reported in the literature. Two of the cases were found in polycystic kidneys. None of the seven patients presented with symptoms related to the tumors and the subsequent clinical course was benign in all cases. Differential diagnosis from renal cell carcinoma is discussed in terms of light and electron microscopic and radiologic aspects. The previously reported cases in the literature are reviewed.