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 < or = 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 < or = 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.