Renal Oncocytoma: Two cases / 대한비뇨기과학회지

ABSTRACT

Renal oncocytomas are neoplasms consisting of oncocytes, which are large epithelial cells with finely granular eosinophilic cytoplasm. The incidence of these tumors are unknown and exceedingly rare but believed to range between 5 and 10% of renal cortical tumors. Although renal oncocytomas are considered benign neoplasms, they are difficult to differentiate from renal cell carcinomas and easily misdiagnosed as carcinomas. We report a case that are indistinguishable from renal cell carcinoma preoperatively and another case showing apparently benign nature, despite its large size, 17 x 15cm and 8 years long history. So a provisional diagnosis of renal oncocytoma was made after renal computed tomography demonstrated characteristic appearance of this tumor and the diagnosis was confirmed with electron microscopy.