The role of renal biopsy to improve diagnosis and management of small renal masses: are there predictive factors for detective higher diagnostic rate? The first Italian study of 100 cases.

BACKGROUND: Incidence of small renal masses (SRMs) has increased over the last decade: in order to reduce overtreatment of benign lesions, renal tumor biopsy (RTB) has been advocated. The primary aim of this study were to establish the rate of diagnostic biopsies and the concordance rate between RTB and surgical pathology with regard to tumor histology. The secondary aim was to identify what predictive factors are associated with an initial diagnostic biopsy. METHODS: We retrospectively analyzed RTB performed in our centre in patients with SRMs between 2015 and 2017. We assessed patient demographics and clinical status, lesion characteristics and procedural factors. The categorical variables were tested with the chi-square test. We used univariate and multivariate analysis to identify what factors are indicative of non diagnostic biopsies. We used the SPSS statistics 23. RESULTS: We performed a total of 100 RTBs to management 94 patients. The initial biopsy was diagnostic in 88 patients (67malignant and 21 benign lesion). The six remaining patients had repeat biopsies, of which four were diagnostic. Complications rate was 5% prevalently local hematoma treated with surveillance. Agreement between biopsy and surgical histology was found in 94% of cases. On contingency analysis and on univariate and multivariate analysis, these factors ( age, tumor size, exophytic location, and type of imaging used) were not predictive with diagnostic biopsy. CONCLUSIONS: RTB for SRMs helps establish pre-treatment diagnosis, reduce overtreatment, with a low risk of complications and high diagnostic rate. In our experience, we did not find predictive factors more likely associated with a diagnostic biopsy.