Biopsy of a renal mass is not the standard of care and is suggested in specific circumstances only. There has been a stage shift within the recent years with renal masses being at lower stages and smaller in size at diagnosis. These patients may potentially be offered a variety of management options changing from observation only to radical surgery. In addition to the change in clinical presentation and management, advances in biopsy and immunohistochemical analysis techniques, along with successful outcomes of renal biopsies have caused an increased interest in the potential role of biopsy in renal masses. There have been some historical reservations regarding the role of renal mass biopsy. We have reviewed the current literature on the accuracy, complications and technical aspects of renal mass biopsy. The role of biopsy in small renal masses (<4cm.) has also been analyzed in detail. Small renal masses are benign in 25-45% and current imaging techniques report them as malignant over 80% of the time. In the current era of avoiding unnecessary treatment and minimal invasive surgery, the knowledge on the biology of a small renal mass has the potential to impact management in these patients. Current series report higher accuracy rates and lower complication rates compared to historical ones. Diagnostic accuracy rate is 96% for series published in the last decade and major complications such as tumor seeding and serious bleeding are almost nil. However, the biopsy results are not universally compared to surgical pathology and thus may harbor significant methodological bias. There is an urgent need for current and well designed studies to shed light to the potential paradigm shift on the role of biopsy of renal masses.

Keywords: kidney, mass, biopsy, cancer