Leydig cell adenoma

Although there was an increased incidence of testicular Leydig cell adenomas in male rats administered 50,000 ppm for 104 wk (Collins et al. 1995), these tumors do not progress to malignancy (Boorman et al. 1990) and have little significance in humans (Cook et al. 1999). The lack of genotoxicity also supports the conclusion that there is no carcinogenic risk for humans. 

Rats fed diets containing 30 or 300ppm ammonium perfluorooctanoate for 2 years had increased liver weights with occasional necrosis and an apparent dose-dependent increase in Leydig cell adenomas, but there was no evidence of an increased incidence of hepatocellular carcinoma. In a follow-up study in male mice, 300ppm in the diet for 2 years caused increases in liver, Leydig cell, and pancreatic acinar cell tumors that may have been associated with the peroxisome-proliferating capabilities of the compound. Ammonium perfluorooctanoate also produced sustained increases in serum estradiol concentrations. ... 

Cook JC, Murray SM, Lrame SR, et al Induction of Leydig Cell adenomas by ammonium perfluorooctanoate a possible endocrine-related mechanism. Toxicol Appl Pharmacol 113 209-217, 1992... 

In mice and rats exposed to 500, 2500, or 5000 ppm 6 hours/day, 5 days/week for up to 104 weeks, the only neoplastic lesion showing an increased incidence was interstitial cell (Leydig cell) adenomas in male rats. The tumor was not considered to be treatment related because of its occurrence in control rats. The lARC has determined that there is inadequate evidence for the carcinogenicity of isopropyl alcohol in experimental animals and humans. 

A number of chemicals are associated with increases in Leydig cell adenoma incidence in rats, but not in mice, for example, clofibrate, fenofi-brate, gemfibrozil, JP-4 jet fuel, lansoprazole, d-Hmonene, oxazepam, methyl-clofenapate, tetrachloroethylene and trichloroethylene [157,166-170]. Perox-... 

Leydig cell adenoma in male rats exposed to MTBE in two studies, but not to either TBA, in one study, or methanol in two ... 

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