The Utility of Renal Mass Biopsy in Large Renal Masses.

Objectives: The role of needle core renal biopsy in large renal masses, defined as lesions larger than 4 cm, is debatable, as larger renal masses are associated with malignant histology. We aim to review the safety and impact of renal biopsy on the management of large renal masses.

Methods: A retrospective, single-center review of all renal biopsies performed between January 2011 and December 2020 at Royal Perth Hospital was conducted. Indications for biopsy, complications and final management plans were correlated to assess the value of biopsies in large renal masses.

Results: In total, 126 biopsies were performed. Indeterminate imaging findings and comorbidities were the main indications for biopsies. We identified 116 (92.1%) diagnostic biopsies and 10 (8.0%) non-diagnostic biopsies due to insufficient samples or inflammatory tissue. Of the diagnostic biopsies, 99 (78.6%) were malignant and 17 (13.5%) were benign. Unnecessary extirpative surgery was avoided in 17 patients. Histology included renal cell carcinoma (96%) and other malignancies such as urothelial carcinoma (3%) and non-Hodgkin's lymphoma (1%). Benign biopsies identified histology including angiomyolipoma (35.3%) and oncocytoma (52.5%). The median follow-up time was 68 months (range 19-132 months).

Conclusion: Renal biopsies in large renal masses may aid in preventing unnecessary surgery, especially in situations where imaging findings are equivocal or in patients with many comorbidities.