Back to 2011 Program

Introduction: Percutaneous needle biopsy is emerging as an option for identifying benign renal neoplasms. The natural history of in situ renal oncocytoma has not been well characterized. We present radiographic and clinical outcomes of patients diagnosed with oncocytoma by a percutaneous needle biopsy.
Materials & Methods: We performed a retrospective review of 899 patients who underwent percutaneous core biopsy of a renal mass at our institution from 1997-2010. We excluded patients with ≤ 12 months follow-up, leaving 40 patients who were diagnosed with oncocytoma by dedicated genitourinary pathologists. Follow-up and treatment outcomes were assessed.
Results:
38/40 patients underwent active surveillance with serial cross-sectional imaging. Median follow-up time was 26.0 months. Median tumor size was 2.5 cm. Median growth rate was 0.1 cm/year. 1 patient underwent delayed intervention (radical nephrectomy) due to an increase in lesion size from 6.6 cm to 7.1 cm over a 9 month period. Surgical pathology confirmed oncocytoma.
2/40 patients received immediate treatment via radical nephrectomy (1) or RFA (1). Tumor sizes were 4.3 cm and 2.6 cm, respectively. Indications for treatment were baseline size and imaging characteristics (1) or patient preference (1). In 1 patient (4.3 cm tumor) who underwent immediate surgery, surgical pathology revealed papillary RCC, Fuhrman Grade 2.
Conclusions: Renal oncocytoma is a slow growing lesion which, in our series, had a median growth rate of 0.1 cm/year. The biopsy diagnosis of oncocytoma may allow patients to avoid the need for intervention; however, our data highlight the need for close follow-up with serial imaging.