[Renal oncocytoma. Report of 13 cases]

We report 13 cases of renal oncocytoma. Urinary symptoms occurred in only 3 cases. The patient's age ranged from 41 to 74 years with an average of 62.3 years. The mean tumor diameter was 5.6 cm (range: 1.5-14). Diagnostic features of ultrasonography, CT scan and, in some instances, angiography were suggestive of renal oncocytoma in 2 patients, but never affirmative, 4 patients were treated by partial nephrectomy. No local or metastatic recurrence was observed with a mean follow-up of 30.8 months, ranging from 6 to 96 months. We assume that the term renal oncocytoma should be restricted to tumors exclusively composed of regular oncocytic cells with an eosinophilic granular mitochondria-rich cytoplasm and an absence of malignant potential. Diagnostic imaging characteristics may sometimes suggest the diagnosis of renal oncocytoma, but cannot eliminate the main differential diagnosis, i.e. granular renal cell adenocarcinoma. When the tumor is small and unifocal, nephron sparing surgery may be considered. Whether or not the diagnosis has been confirmed by fine needle aspiration, conservative surgery must be controlled by intraoperative frozen sections of the tumor and surgical margins.