Renal oncocytoma: a benign tumour on the increase.

Renal oncocytoma is an uncommon tumour which is being diagnosed with increasing frequency in recent years. Traditionally, these renal tumours were considered to be histological variants of renal adenocarcinomas, with no prognostic significance of their own. Several recent retrospective studies have demonstrated that they are a separate benign entity; therefore, differentiation and identification of these tumours are of the utmost importance.