Renal masses detected by general health checkup

Background: A total of 60 604 persons underwent a general health checkup at Toma Hospital, Saitama, Japan, between January 1993 and June 1997, and tra nsabdominal ultrasonography (US) was performed on all persons. We investiga ted the usefulness of transabdominal US in detecting renal tumors during ge neral health checkups. Methods: A definite diagnosis was made in cases where the re-examination by US revealed calculus with acoustic shadow or a simple cyst. Computed tomog raphy (CT) was conducted in patients suspected of having a renal tumor, and a diagnosis of renal angiomyolipoma (AML) was made if plain CT gave eviden ce of a fatty component. Patients diagnosed as having a renal cell carcinom a (RCC) with non-uniform enhancement underwent nephrectomy. If a definite d iagnosis could not be made even by contrast CT, the monitoring by US and co ntrast CT once a year was continued. Results: Of 97 (0.16%) patients whose transabdominal US findings indicated a diagnosis of suspected renal tumor, 58 underwent the re-examination by US ; of these, CT was conducted in 47. Detailed US revealed a hyperechoic patt ern in 44 patients, a mixed pattern in nine and an isohypoechoic pattern wi th internal echo in five. By plain CT, 24 patients were diagnosed as having AML, and two as having renal calcification. Contrast CT enabled a diagnosi s; of renal cyst to be made in two patients and renal tumor in 14. All 14 p atients with RCC except one underwent nephrectomy, which provided pathologi c evidence supporting the diagnosis. Five patients had a tumor unidentifiab le by CT, with continuing periodic follow-up by US and CT. Eleven patients underwent no CT. Conclusion: Of the 60 604 persons who underwent a general health checkup, w e found 14 cases of RCC and 24 cases of AML. As a small RCC has a favorable prognosis, patients greatly benefit from early detection; therefore, we sh ould recognize the importance of identifying renal masses by US screening d uring general health checkups.