Renal oncocytosis: management and clinical outcomes

Purpose: Renal oncocytosis is a rare pathological condition in which renal parenchyma is diffusely involved by numerous oncocytic nodules in addition to showing a spectrum of other oncocytic changes. We describe our experience with renal oncocytosis, focusing on management and outcomes.

Materials and methods: A total of 20 patients with a final pathological diagnosis of renal oncocytosis from July 1995 through June 2009 were included in the analysis. Patient demographics, intraoperative variables and postoperative outcomes are reported.

Results: Median age at nephrectomy was 71 years (IQR 59-75). Of the patients 15 (75%) had bilateral disease. There were 23 operations (9 right side, 14 left side) performed on 20 patients, and of these procedures 13 (57%) were partial nephrectomies and 10 (43%) were radical nephrectomies. Median dominant tumor mass diameter was 4.1 cm (IQR 3-6.4, range 1 to 14.6). The most common dominant tumor histology was hybrid tumor between oncocytoma and chromophobe renal cell carcinoma in 13 of 23 specimens (57%), followed by chromophobe renal cell carcinoma in 6 (26%), oncocytoma in 3 (13%) and conventional renal cell carcinoma in 1 (4%). Ten patients (50%) had preexisting chronic kidney disease before nephrectomy and chronic kidney disease developed in 5 more after surgery. After a median followup of 35 months no patients had metastatic disease.

Conclusions: Patients with renal oncocytosis usually present with multiple and bilateral renal nodules. Half of the patients had chronic kidney disease at diagnosis and 25% had new onset of chronic kidney disease. No patient had distant metastatic disease during followup. Our management approach is to perform partial nephrectomy when possible and then use careful surveillance of the remaining renal masses.