Renal oncocytoma: a clinicopathologic study of a case with review of the literature.

A peculiar case of renal oncocytoma was studied by clinical, light- and electron-microscopic examinations. The neoplasm, which was first discovered 21 years ago, at operation turned out to be very large, well-circumscribed and lacking any feature of aggressiveness. Histologically, it was composed totally of oncocytes without relevant atypia or necrosis. Ultrastructurally, a cytoplasmic filling by mitochondria with paucity of other organelles and filaments also supported the diagnosis. The authors also reviewed the literature and emphasized the diagnostic criteria of this type of tumor.