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Introduction:The long-term outcomes of renal oncocytomas and their natural history has not been well characterized. In this study we review the in-situ natural history and clinical outcomes of renal mass biopsy (RMB) proven oncocytomas at our institution.
Materials & Methods:We performed a retrospective review of our database of 1233 RMBs between 1998-2012. Lesions with a pathological diagnosis of oncocytoma on percutaneous biopsy were identified. Surveillance and follow-up outcomes were assessed.
Results: A total of 109 lesions had pathological diagnosis of oncocytoma on image-guided (US:CT=7:102) RMB. Median age was 72 years (range:40-91 years) and 69/109 were male. The majority of lesions were solid (n=106,97%) with a median size of 2.5cm (range: 0.9-7.8cm). A total of 54 lesions were followed with a minimum of one additional imaging study. 24 lesions were either stable or decreased in size during a mean 2.4 ± 2.1years of follow-up. Of the 30 lesions which grew in size the mean rate of growth was 0.38cm/year. However, the mean rate of growth for the overall followed cohort was 0.07cm/year. Two patients underwent RFA, 4 underwent nephrectomy, and 2 were re-biopsied.
Conclusions: This is the largest series of biopsy proven oncocytomas reported to date. Renal oncocytomas are slow growing. Our data suggests that lesions of this type with growth rates ≤ 0.3cm/yr may be safely followed with serial imaging.