Small renal mass: to treat or not to treat.

An increasing number of small renal masses (SRMs) are being detected with modern cross-sectional imaging. The natural history of SRMs is mostly unknown. Initial active surveillance (AS) is a reasonable treatment option for small renal masses (SRMs) < 4 cm in the infirm patient with major comorbidities. Partial nephrectomy (PN) is the established treatment for T1a tumors, provided that the operation is technically feasible and the tumor can be completely removed. Laparoscopic and, most recently, robotic PN have functional and oncologic outcomes comparable to open PN, but are technically demanding procedures. Radical nephrectomy (RN) should be limited to those cases where the tumor is not amenable to PN. Percutaneous needle biopsy of SRMs can be safely performed and has the potential to characterize SRMs histologically. It is best utilized in conjunction with ablative technologies. However, ablative therapies should be reserved for carefully selected patients who are poor surgical candidates.