[Incidental renal cell carcinoma]

We reviewed the cases of incidental renal cell carcinoma that had been treated at the Kitasato University Hospital between July, 1971 and December, 1989. Forty one of the 170 (24.1%) cases were found without any direct signs of renal cell carcinoma. The patients were between 30 and 78 years old (mean 55.0 years) and consisted of 29 males and 12 females. Fifteen cases were detected at the general health check-up and the remaining 26 during the postoperative follow-up for other malignant tumors or other diseases. Twenty three cases were identified by ultrasonography followed by computed tomography (CT) and excretory pyelography in 4 cases each. Especially, the number of patients incidentally found by ultrasonography had increased in the recent 8 years. Urinalysis did not show any microhematuria in 31 of the 37 cases (83.7%), and no tumor mass could be detected by excretory pyelography in 3 cases. We believe that ultrasonography may be valuable as a screening modality for early detection of renal cell carcinoma and should be used as a screening method at the routine health check-up.