Dilemmas in diagnosis and natural history of renal oncocytoma and implications for management.

INTRODUCTION: Oncocytomas have traditionally been treated with surgical excision; however, their excellent long-term prognosis has popularized conservative and minimally invasive ablative techniques. We evaluated the evolving management and natural history of renal oncocytomas and investigated the relationship between radiological and histopathological diagnosis.

METHODS: We performed a 17-year retrospective cohort study on all patients with a confirmed histopathological diagnosis of renal oncocytoma. The primary outcome variables were long-term outcomes, coexistence with renal cell carcinoma, and development of metastatic disease.

RESULTS: A total of 38 oncocytomas were reported in 36 patients. Of the 36 patients, 29 (81%) were diagnosed incidentally. Oncocytoma was considered in the differential diagnosis in 4 oncocytomas (10.5%). In total, 34 patients underwent early surgical intervention; of these, 27 (79.4%) underwent radical nephrectomy and 7 underwent partial nephrectomy (20.6%). Four patients (11.1%) were managed conservatively with surveillance. No patients developed recurrence or metastatic disease after a median follow-up of 84 months (range: 4-178).

CONCLUSIONS: The diagnostic accuracy for imaging modalities in renal oncocytoma is poor. Surveillance or minimally invasive ablative techniques are appropriate in selected patients with biopsy-proven oncocytoma that are not increasing in size.