Small Renal Mass—To Biopsy or Not? The Role of Biopsy in Evaluation

Abstract

Although the majority of incidentally diagnosed small renal masses (SRMs) leading to surgery are found to be malignant, most are low-grade, early stage tumors believed to have indolent biology, and 20–30% are benign [1,2]. This presents an increasingly common diagnostic dilemma to urologists. Axial imaging identifies most of these patients; however, tissue sampling via percutaneous core biopsy can provide clinical evidence of histology, subtype, and grade to guide risk stratification and management beyond suspicion from imaging. As with any diagnostic test, performance characteristics must be evaluated in relation to potential harms, and the true utility should be objectively considered for specific clinical situations. A current systematic review effort by the US Agency for Healthcare Research and Quality specifically evaluated diagnostic accuracy of renal mass biopsy for clinically localized renal masses (>80% of included tumors were SRMs) in the global literature, incorporating several large and recently reported series [3]. Importantly, to best determine true performance characteristics, this systematic review included only studies with pathologic confirmation of biopsy (ie, the diagnostic test was compared with the gold standard, surgical pathology). Initial biopsy led to