To evaluate patient and tumor characteristics associated with percutaneous renal mass biopsy (RMB) among patients with small renal masses (SRMs) and assessed the impact on clinical decision-making.

For 204 consecutive patients presenting with a clinical stage T1 renal mass at our institution, we collected data regarding patient demographics, comorbidity, renal function, anatomic factors, and treatment plan. We then assessed the association between these characteristics and receipt of RMB, and between biopsy results and initial treatment decision.

Among 204 patients, 78 (38%) received RMB. Of the demographic and physiological parameters, only non-Caucasian race and family history of renal cell carcinoma were associated with biopsy (P < .05). In contrast, RMB was significantly associated with several anatomic factors, including larger tumor size, solitary kidney, juxta-hilar tumor location, greater body mass index (BMI), and high-complexity nephrometry score (P < .05). On multivariable analysis, only BMI >25 kg/m², juxta-hilar location, and high-complexity nephrometry score remained significantly associated with RMB (P < .05). Biopsy was performed in a greater proportion of patients who ultimately underwent radical nephrectomy vs nephron-sparing surgery (NSS) (P = .04). Furthermore, RMB results directly impacted treatment, with active surveillance more frequent among patients with benign or favorable histology and surgical management more common among patients with more aggressive disease (P < .001).

At our institution, one-third of patients presenting with a SRM undergo RMB, most commonly among patients with complicated anatomic and/or tumor considerations. Because these factors may limit the feasibility of NSS, biopsies are being used to guide decision-making aimed at minimizing total kidney loss.