Bilateral renal oncocytoma: report of 2 cases and literature review

We report on 2 patients with bilateral renal oncocytoma treated in the last 5 years. One patient underwent bilateral partial nephrectomy for a solitary tumor in each kidney. Both tumors were confirmed to be renal oncocytomas by light and electron microscopic examination. After 4 years this patient had no evidence of local recurrence or distal metastasis. The second patient presented with bilateral multiple renal oncocytomas. Transabdominal bilateral renal exploration revealed 2 tumors in the right kidney and 3 tumors in the left kidney. Right radical nephrectomy and enucleation of the left renal tumors were performed. Examination by light and electron microscopy confirmed that all tumors from both kidneys were oncocytomas. Only 8 cases of bilateral renal oncocytoma have been reported in the literature, including our 2 cases. In 6 of these 8 cases the tumors were multicentric, which may be a characteristic of bilateral renal oncocytoma. Recognizing the coexistence of multicentricity and bilaterality is important because more conservative treatment is required. However, a favorable prognosis may still be anticipated.