Renal oncocytoma. A rare entity in Poland.

Renal oncocytoma represents a special category of renal tumours and accounts for 3-5% of renal neoplasms. Usually they are incidental findings. Most reports have demonstrated their benign nature but a few cases of high-grade oncocytomas were reported to have metastasized. In Poland, between 1971 and 1991, 7 patients (4 women, 3 men) underwent radical nephrectomy for oncocytoma. The author describes here one case of rare oncocytoma malignum.