Morphologic characteristics of benign and malignant renal cell tumors in control and 2-acetylaminofluorene-treated BALB/c female mice.

A total of 108 mice with renal cell tumors were obtained from a total of 25,916 control and 2-AAF-treated BALB/c female mice. A total of 119 renal cell adenomas and 37 renal cell carcinomas from the 108 mice were classified morphologically. The 119 renal cell adenomas were divided into cystic (32%), cystopapillary (29%), papillary (24%), and solid (15%). The 37 renal cell carcinomas were divided into tubolosolid (16%), tubolopapillary (49%) and tubulopleomorphic (35%). Pulmonary metastases occurred only in the tubulopleomorphic adenocarcinomas. In mice having renal cell tumors and surviving less than 650 days, the renal cell carcinomas were usually multiple and renal cell adenomas often coexisted in the same kidney. In mice having renal cell tumors and surviving more than 650 days, the renal cell carcinomas usually consisted of single large tumors without coexisting renal cell adenomas. The results suggest that the renal cell adenoma may progress to renal cell carcinoma. The various dose levels of 2-AAF did not significantly affect the incidence of renal cell tumors.