ABSTRACT
Renal oncocytomas account for approximately 5% of renal parenchymal tumors. Usually it has unilateral solitary oncocytic nodule, but bilateral multifocal renal oncocytomasis is rare. The term renal oncocytoma should be used to characterize a well-differentiated renal epithelial tumor with eosinophilic granular cytoplasm that has benign behavior and favourable progress. Also, multiple oncocytoma distributed diffusely in both kidneys is termed renal oncocytomatosis Because of the benign nature, multicentricity, possible bilaterality and absence of pathognomonic radiographic features, renal oncocytomas should be considered in differential diagnosis of solid masses, especially renal cell carcinoma. We report a patient with bilaleral multifocal renal oncocytomatosis, who had progressive renal failure. Renal oncocytomatosis was diagnosed pathologically after bilateral nephrectomy.