Background: Solid renal masses are found increasingly. Further analysis of the characteristics of solid renal masses is useful for optimal treatment.
Methods: A retrospective analysis of all solid renal masses was conducted from December 1998 to May 2003 at the Urology Department, Central University Hospital of Saint-Etienne, France. A total of 162 solid renal masses were treated. The preoperative imaging diagnosis of ultrasound and computed tomography, and final pathological results were reviewed.
Results: One hundred and forty-five tumors were pathologically confirmed to be renal cell carcinomas (RCC); 17 tumors (10.5%) were benign. There were eight renal oncocytomas, eight renal angiomyolipomas and one benign mixed epithelial/stroma tumor. Three oncocytomas and five angiomyolipomas were strongly suspected before surgery. The majority of the benign tumors were ≤4 cm. The percentage of small benign tumors (≤4 cm) was significantly higher than large benign tumors (>4 cm). Although it is possible to use imaging to detect some benign tumors, the majority of benign tumors cannot be diagnosed definitively by imaging before surgery.
Conclusions: Malignancy in solid renal masses is tumor-size related. Benign solid renal tumors appear mainly as small-sized tumors. The preoperative differentiation between an RCC and a benign tumor can be difficult. Our data suggest that a biopsy is necessary in selected patients to achieve the maximum accuracy in order to provide optimal treatment.