Imaging guided biopsy of renal masses: indications, accuracy and impact on clinical management.

PURPOSE: We evaluated the indications, accuracy and impact of image guided biopsy of focal renal masses.
MATERIALS AND METHODS: We retrospectively reviewed 79 image guided renal biopsies in 73 patients. Indications, imaging, and histological and clinical features were analyzed. We assumed that nephrectomy, partial nephrectomy or surgical biopsy of suspicious masses would be done when no percutaneous biopsy had been performed. A change in management was defined as surgical to nonsurgical.
RESULTS: Clinical management was altered due to results in 32 of the 79 biopsies (41%) in cases managed nonoperatively, including positive and negative biopsies in those followed clinically and with imaging. Of 79 biopsies 49 (62%) were diagnosed positive for malignancy, including 15 (31%) that were not and 34 (69%) that were renal cell carcinoma. The histological diagnosis was negative on 25 biopsies (32%) and positive or negative on 74 (94%). All 5 of the 79 false-negative biopsies (6%) were due to insufficient tissue and involved highly suspicious imaging findings that required further evaluation, such as repeat biopsy or surgery. Renal cell carcinoma was identified in 4 of the 5 cases. In 12 of the 24 patients (50%) with a pre-biopsy history of nonrenal cancer biopsies were diagnostic of nonrenal cancer. No patient had major complications and in 4 small hematomas were treated with observation only.
CONCLUSIONS: Image guided renal mass biopsy is safe, reliable and accurate, and it changes clinical management in many cases by avoiding nephrectomy or other surgical options. Radiologists should promote imaging guided biopsy as a potentially useful option for managing suspicious or indeterminate renal masses.