Adenocarcinoma of the kidney. III. Histogenesis of renal adenocarcinomas induced in rats by N-(4'-fluoro-4-biphenylyl)acetamide.

The histogenesis of renal adenocarcinoma induced in F344 rats by the carcinogen N-(4'-fluoro-4-biphenylyl)acetamide (FBPA) was described in order to clarify the site of origin of this neoplasm within the nephron. FBPA was added to the diet up to 48 weeks, and the animals were killed at intervals from 4 to 52 weeks after initiation of the carcinogenic diet. As seen by light microscopy, tumors appeared to arise from the pars recta of the proximal tubule in a series of stages progressing from focal hyperplasia with dysplasia to development of small, then large, neoplastic nodules composed of moderately basophilic, closely packed tumor cells arranged in individual aggregates or lobules surrounded by basement membrane-like material. Karyomegaly, cystic lesions, foam cell lesions, interstitial fibrosis, and casts also accompanied tumorigenesis in this animal model.