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.