Renal oncocytoma, benign or malignant?

ABSTRACT

Introduction: Renal oncocytoma is a benign renal tumor, which is commonly asymptomatic and discovered incidentally with diagnostic imaging. This benign tumor occasionally co-exists with a malignant neoplasm, which may be present within or near the oncocytoma; in addition a few rare cases of renal oncocytoma have simulated a malignant course, showing extension to branches of the renal vein or distant metastasis