ABSTRACT
BACKGROUND: Renal oncocytoma is an uncommon tumor, classified as a benign renal neoplasm in the World Health Organisation classification of renal tumours. Despite it there were described several reports with invasive histopathologic features. CASE REPORT: We describe a case of renal oncocytoma with bizzare cells and invasion of renal sinus fat tissue. We performed immunohistochemical analysis of the case and a review of relevant literature. CONCLUSION: In order to set up the right dia-gnosis the perfect co-âoperation of clinicians and pathologists is necessary. In our opinion, in accordance with other authors, the renal oncocytomas should be considered as having a very low rather than no malignant potential, in spite of clinically benign behavior, supplementing a hypothesis, whether renal oncocytomas may be considered as a precancerous lesion of chromophobe carcinoma.