[Renal oncocytoma. Retrospective study of 38 cases].

38 cases of renal oncocytoma were recognized at Cochin's hospital from 1982 to 1991. Accurate diagnosis was not possible before performing surgery. However, a benign tumor appearance on the preoperative morphologic investigations and an evocative peroperative macroscopic aspect of renal oncocytoma, allowed us to realize a conservative surgery in 4 cases. Follow-up of 27 patients (11 lost to follow-up) showed a benign clinical behaviour in all cases, de spite of invasion of the perirenal fat in 2 cases, and tumoral thrombosis of a proximal branch of the renal vein in 1 case. No metastases occurred after a mean follow-up of 32.5 months, within range from 11 to 101. Our experience as well as the literature leads us to believe that renal oncocytoma is a benign tumor. We conclude that conservative surgery must be systematically considered when peroperative histological examination assert the diagnosis of renal oncocytoma, especially when the tumoral diameter is less than 5 cm.