Diagnostic accuracy of percutaneous renal mass biopsy in patients undergoing robot-assisted partial nephrectomy for localized renal cell carcinoma.

Objective: The aim of this study was to assess the diagnostic accuracy of renal mass biopsy in determining tumor subtype and grade, in patients with renal cell carcinoma who subsequently underwent partial nephrectomy.

Material and methods: This retrospective, single-institution study included consecutive patients who underwent a renal mass biopsy revealing renal cell carcinoma, followed by robot-assisted partial nephrectomy between May 2016 and April 2023. The diagnostic accuracy of renal mass biopsy was evaluated using the final histopathology on the surgical specimens as the reference standard and presented as proportions.

Results: We identified 275 patients diagnosed with renal cell carcinoma on biopsy, all of whom subsequently underwent surgery. The median age was 65 years, and 30% of the patients were female. The overall accuracy of tumor subtype identification in the biopsy was 89% (95% CI: 85%-93%). A Fuhrman grade was assigned in both biopsy and surgical specimen in 156 patients with clear cell renal cell carcinoma. The concordance between biopsy and surgical specimen for exact Fuhrman grade was 50% (95% CI: 42%-59%) but increased to 92% (95% CI: 86%-95%) when pooled into low grade (Fuhrman grades 1-2) and high grade (Fuhrman grade 3).

Conclusion: The current study supports the use of renal mass biopsies in patients with small renal masses if it will influence the clinical decision as it offers valuable diagnostic information that assists clinicians in the diagnosis, risk assessment and management of small renal masses.