Diagnostic accuracy and clinical impact of imaging-guided needle biopsy of renal masses. Retrospective analysis on 150 cases

Objective: To review our method of perform needle biopsies of renal masses. Methods: We analysed 150 consecutive imaging-guided percutaneous biopsies. The pathological diagnosis was verified on clinical outcome in 129 cases (40 surgical resection, 53 thermal ablation, two medical treatment and 34 watchful waiting). Twenty-six patients underwent fine-needle aspiration biopsy (FNAB), 45 core-needle biopsy (CB) and 58 FNAB + CB. After review by two expert pathologists, cumulative accuracy of all FNAB (84) and all CB (103) was calculated. The rate of complications and mass management other than surgery was estimated. Results: The final diagnosis was malignancy in 97 cases (benign mass in 32). FNAB correctly diagnosed 64/84 masses (76.2%), CB 96/103 (93.2%). Of 58 masses submitted for both FNAB and CB, CB provided a 22.5% accuracy improvement. Major and minor complications occurred in 0% and 5.3%. Renal biopsy altered clinical management in 89/129 cases (68.9%), in terms of choosing therapeutic options other than surgery. Conclusion: CB is more accurate than FNAB and should be preferred in renal mass biopsy. FNAB may precede CB when an expert pathologist can immediately evaluate the samples. Renal biopsy influences renal mass management.