Renal Tumor Biopsy: Rationale to Avoid Surgery in Small Renal Masses

The use of renal tumor biopsy (RTB) for small renal masses (SRMs) in daily practice, although safe and accurate, is unusual. Considering the large number of benign tumors in patients with renal masses < 4 cm, some patients with benign tumors are directly referred for surgery instead. This study aimed to report the diagnostic rates of RTB, determine the concordance with surgical pathology, and assess the number of procedures that could have been avoided. We retrospectively studied 255 patients who underwent RTB at our institution in 2010-2019. Of them, 73 were excluded from the analysis (exclusion criteria: > 4 cm, cystic lesion, missing data). The remaining 182 with undetermined SRMs ≤ 4 cm underwent RTB under computed tomography guidance.

Biopsies were diagnostic in 154/182 (84.6%) cases. Of the non-diagnostic biopsies, 11 were diagnostic when repeated. When RTB was performed of all undetermined SRMs, active treatment (surgery or cryotherapy) was avoided in 50/182 patients (27.5%) because of a benign diagnosis, while 9/182 patients (4.9%) underwent surveillance after a shared multidisciplinary decision. The overall diagnostic rate was 90.6%. All adverse events (approximately 4%) were Clavien-Dindo grade I and did not require active treatment. RTB histology results and nuclear grade were highly concordant with the final pathology (96% and 86.6%, respectively). On univariate logistic regression analysis, male sex was the only contributing factor of diagnostic biopsy. RTB of SRMs should be performed more frequently as part of a multidisciplinary decision-making process since it avoided unnecessary surgical treatment in 1 of 3 patients in our institution.