Accuracy of Percutaneous Core Biopsy in Management of Small Renal Masses

Objectives To determine the sufficiency and accuracy of percutaneous core needle renal biopsy in patients with small renal masses (SRMs). Methods A retrospective chart review was performed on those patients who had undergone image-guided 18-gauge core renal biopsy of SRMs ≤4 cm from February 1999 to October 2006. The information obtained included the initial biopsy technique, pathologic findings, and the clinical outcome. Results A total of 110 renal biopsies were performed for masses ≤4 cm. The average renal mass size biopsied was 2.7 cm, with a median of 4 cores taken. Of the 110 biopsies, 100 (90.9%) were sufficient for diagnosis and 10 (9.1%) were indeterminate or provided insufficient tissue. Of the 100 diagnostic biopsies, 65% were interpreted as malignant and 35% as benign. There were 8 complications (7.2%), with 2 postprocedural hematomas (1.8%). Thirty-four patients underwent surgical extirpation; the ultimate histopathologic accuracy of biopsy compared with the final surgical pathologic finding was 100% (34/34) in these patients. Conclusions Image-guided core needle biopsy is highly accurate in SRMs, and more than one third of these lesions will be benign. With a low complication rate, core biopsy provides a histopathologic diagnosis that aids in decision-making for the growing number of incidentally detected SRMs.