Organ sparing surgery for giant bilateral renal oncocytoma.

Abstract

Renal oncocytoma, which is a renal cortical tumor according to the Heidelberg and WHO classifications, represents about 5% of renal tumors. This lesion occurs more commonly in males than in females and has generally the same age incidence as that of renal cell carcinoma. To our knowledge we report the first case of successful organ sparing surgery for giant bilateral renal oncocytoma. CASE REPORT A 63-year-old woman with a history of headache and weight loss underwent computerized tomography (CT), which revealed a 16 12 15 cm. tumor on the caudal pole of the right kidney and an 11 8.5 12 cm. tumor with central necrosis on the cranial pole of the left kidney (fig. 1). The mass on the right side was seen compressing the inferior vena cava subtotally and obstructing the ureteropelvic junction, causing dilatation of the collecting system. Serum creatinine was 1.0 mg./dl. (normal 0.5–1.0). Metastatic evaluation was noncontributory. With a presumptive diagnosis of bilateral renal cell carcinoma the patient underwent organ sparing surgery of the smaller tumor on the left side with intraoperative cold ischemia. Intraoperative frozen section showed renal oncocytoma, and histological examination of the entire specimen confirmed the diagnosis. The large mass on the right side required a careful decision regarding further surgery. Therefore, CT guided biopsy was performed. Histological examination again demonstrated renal oncocytoma and, thus, organ sparing surgery was an option. Four weeks after the first operation transperitoneal resection of the larger tumor on the right side through median laparotomy was performed. Final diagnosis was again renal oncocytoma. Nine days after the second operation excretory urography revealed prompt excretion of contrast medium on both sides and no extravasation (fig. 2). The patient was discharged home the same day in good general condition. At 1-year followup she was asymptomatic with a stable serum creatinine of 1.1 mg./dl. DISCUSSION Renal oncocytoma was initially described in 1942 by Zippel1 but it took more than 30 years to establish renal oncocytoma as a distinct entity in the differential diagnosis of solid renal parenchymal masses. Current series suggest that 3% to 7% of solid renocortical tumors are renal oncocytomas.2 According to the literature 4% to 5% of these tumors occur bilaterally, and coincidence with renal cell carcinoma is reported to be 10%.3 Oncocytomas are mostly asymptomatic, and the majority of tumors are discovered incidentally. Hematuria, flank pain and palpable mass are infrequent findings. There is no method of determining tumor histology