Frequency, Clinical Presentation and Evolution of Renal Oncocytomas: Multicentric Experience from a European Database

Objectives: To understand the clinical behavior of renal oncocytoma in a retrospective analysis of a European multicentric nephrectomies database. Methods: The records of 891 patients who underwent surgical resection of renal neoplasm were reviewed. Relevant clinical and pathological data for each patient were retrieved in a database. Results: Thirty-two (3.6%) cases of renal oncocytoma were identified. Twenty patients (62.5%) were asymptomatic. No case of lymphatic invasion or metastatic disease, nor any evidence of vascular or fat tissue invasion was found. Thirty-one cases (96%) exhibited low mitotic activity. In one case the presence of renal clear cell carcinoma (diameter: 1.5cm) was found. After a median follow-up of 42 months, 87.5% of patients were alive with no evidence of tumor, while 9.3% of patients had died for non-malignant causes. One patient had not treated the tumor surgically and was disease-free at a 27-month follow-up. Conclusions: Renal oncocytoma is a benign neoplasm, characterized by slow growth and excellent prognosis after surgery. Nephron sparing techniques may be adequate for tumor removal.