The use of renal biopsy in the kidney tumor management: A retrospective analysis of consecutive cases in a referral center

Introduction: Ultrasound-guided renal masses biopsy (RMB) is a useful and underestimated tool to evaluate suspected renal tumors. This study aimed to assess the safety and feasibility of this technique. Materials and Methods: Data of 80 patients with suspected primary or secondary kidney tumors who underwent RMB between January 2012 and December 2020 were included in this retrospective study. Twelve patients were excluded due to incomplete data. Biopsy outcomes were collected through our electronic medical records system and then compared with definitive pathology. Results: RMB was performed in 68 cases. Pathological examination reported 43 (63%) malignant cases, while RMB was negative in 15 (22%) samples. On the other hand, a benign lesion was present in 8 (12%) cases, and 2 (3%) biopsies were non diagnostic. One major and one minor post-procedure complication were reported among the patients. A total of 31 patients underwent renal surgery including 19 partial and 12 radical nephrectomies. Out of them, 4 patients had a negative biopsy, but radiological imaging strongly suggested malignancy. The concordance between biopsy and definitive pathology occurred in 22 out of 31 (71%) cases, with a higher rate among the masses greater than 4 cm, 9/11 (82%) compared to smaller ones 13/20 (65%). Pathologic examination of the 4 cases with negative biopsy showed 3 renal cell and a translocation renal cell carcinoma. Conclusions: Ultrasound-guided biopsy for renal masses is a safe and effective procedure. Its ability to identify malignancy is evident, especially for primary renal tumors. However, low concordance between biopsy and definitive pathology in cases with negative biopsies, especially for tumors < 4 cm, does not reliably guarantee the absence of tumor and, therefore, strict follow-up or repeat biopsy may be indicated.