Diagnostic accuracy of pre-operative imaging findings in presumed clinical T1a renal cell carcinomas.

Despite the development of recent imaging modalities, certain pathological misdiagnoses remain for surgical specimens of presumed small renal cell carcinomas (RCCs). In the present study, a retrospective analysis of benign pathological lesions diagnosed as small RCC prior to surgery was performed. In total, the cases of 196 sporadic renal tumors that was surgically treated as clinical T1a RCCs were reviewed, and the accuracy of the pathological diagnoses was calculated. The pre-operative findings for benign pathological lesions was investigated, and the lesions were observed in 13 (6.63%) of the 196 tumors. Pre-operative computed tomography images were obtained in all cases, and magnetic resonance images were available in 10 cases. The diagnostic accuracy of imaging modalities was significantly lower in the tumors with a diameter of ≤20 mm. In all cases, the possible pathological diagnosis of RCC could not be excluded even by retrospective imaging analysis. Several benign pathological lesions were found in small renal masses presumed to be clinical T1a RCC. In conclusion, there may be limitations to the pre-operative imaging for certain types of small renal mass.