Renal Oncocytoma: A Case Report and Review of the Literature.

Renal oncocytomas (ROs) are uncommon, benign epithelial tumors of the kidney. We report a case of an asymptomatic RO incidentally detected in a 34-year-old woman that was difficult to differentiate preoperatively from renal cell carcinoma (RCC). Abdominal ultrasonography revealed a right renal mass measuring 2 cm, while MRI showed a cystic-solid nodule without a central scar in the mid region of the right kidney. The patient underwent partial right nephrectomy via the lumbar region without complications and was discharged on the seventh postoperative day. Although MRI showed no central scar, immunohistochemistry and histopathological examination of the specimen demonstrated the characteristic features of RO without evidence of malignancy. This report discusses a small, asymptomatic RO and its differentiation from RCC using radiological imaging, immunohistochemistry, and histopathological examination to establish a definitive diagnosis and avoid misdiagnosis based solely on radiological features.