RESUMEN
Background: Small renal masses (SRM) are defined as complex organ-confined solid or cystic lesions < 4 cm. Up to 20% of these can be benign. A conservative management with active surveillance can be done in some patients. However, it is difficult to identify patients with a higher risk of malignancy. Aim: To characterize the clinical, radiological and histopathological aspects of patients with SRM, analyzing predictive factors for tumor aggressiveness. Material and Methods: Retrospective analysis of a cohort of patients undergoing partial or total nephrectomy for renal tumors between 2006 and 2016. All tumors of 4 cm or less were included. Four histological groups were defined: benign, favorable, intermediate and unfavorable. Two categories of risk were also defined: low and high. Preoperative clinical and radiological variables of these patients were analyzed. Results: Data of 152 patients were analyzed. Six percent had a benign histology, and the majority was of intermediate risk (74%). According to histological type, clear cell carcinoma was the most common type (74%). Three percent were benign angiomyolipomas. No malignancy predictive variable was identified. Conclusions: In these patients, the percentage of benign SRM was low. No variable that could predict the presence of a benign or malignant lesion in the definitive biopsy was identified.