Core Biopsy of Solid Renal Masses under CT Guidance

Objectives: To determine for which tumors a percutaneous computed tomography (CT)-guided biopsy might be beneficial to distinguish between benign and malignant lesions. Methods: The author analyzed the international literature since 2000 that deals with biopsy of renal masses, which involved more than 1000 patients. He reports also on his own experience. Results: The accuracy of renal biopsy to differentiate malignant and benign tumors is 90%. The accuracy of renal biopsy for the subtype pathologic evaluation of tumors is 80–90%, but the accuracy for nuclear grade is only 50–75%. However, all renal masses do not deserve biopsy, and this evaluation should be restricted to only intermediate masses that cannot be clearly classified by the imaging technologies. On CT scan, intermediate masses were solid tumors with no hypervascularization, with no early or intense enhancement, with homogenous enhancement but no negative density. The size of the tumor must be considered (<4 cm) to indicate biopsy. These intermediate tumors accounted for 25% of the whole renal masses. Conclusions: Core biopsy of renal tumor is accurate and safe for the diagnosis of renal masses. It can be indicated for intermediate masses. # 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved.