Incidental small renal tumors accompanying clinically overt renal cell carcinoma.

We searched 66 kidneys with renal cell carcinoma for subcapsular or intraparenchymal small nodules in the apparently normal-appearing portion of the kidney. Differentiation between adenoma and carcinoma was done according to histological characteristics. Of the 66 kidneys 20 (30 per cent) contained a total of 58 small nodules ranging from 1 to 15 mm. in diameter. In 9 kidneys the lesions were consistent histologically with carcinoma, in 7 with adenoma and in 4 with carcinoma plus adenoma. Thus, 13 of the 66 kidneys (19.7 per cent) contained small carcinoma. In view of the high incidence of small carcinoma accompanying clinically overt renal cell carcinoma, we suggest that the indications for partial nephrectomy in the management of renal cell carcinoma should be reevaluated.