Percutaneous renal mass biopsy after indeterminate diagnostic imaging results

We conducted a retrospective study to examine the efficacy of renal mass biopsies in our hospital. Twenty-six patients (18 male, 8 female ; median age, 69 years ; range, 42-85 years) with renal masses were divided into two groups. Group 1 (n＝9) underwent renal mass biopsies after completion of diagnostic imaging tests that needed a pathological diagnosis before treatment other than extirpative surgery, and group 2 (n＝17) underwent renal mass biopsies after completion of indeterminate diagnostic imaging tests that did not rule out malignancy. The median tumor size was 2.8cm (range, 0.8-15 cm), and the median number of biopsy cores obtained was two (range, 2-4). There were no biopsy-associated complications that required intervention. In group 1, 100% (9 of 9) of the renal mass biopsies were diagnostic, and the pathological findings corresponded to the respective diagnosis obtained by imaging tests, most of which were clear cell carcinoma. In group 2, 59% (10 of 17) of the biopsies were diagnostic. The imaging characteristics of the seven nondiagnostic biopsies in group 2 were low blood flow and poor peripheral clarity. On the other hand, renal mass biopsies were indispensable for some patients in group 2 in whom the pathological findings led to a decision of treatment strategy. In conclusion, renal mass biopsies should be considered in view of their ability to compensate for limitations of imaging tests and their low frequency of complications.