Carcinoma of the perianal gland and associated structures in 1,2-dimethylhydrazine treated mice.

Male C57BL/Icrf alpha t mice receiving long courses of weekly subcutaneous injections of 8.25 or 12.5 mg/kg, 1,2-dimethylhydrazine (DMH) developed perianal carcinomas as well as tumours at other sites. Tumours of the perianal gland or its associated hair root sheath and overlying skin included sebaceous gland adenocarcinomas, often with squamous metaplasia, analogous to those in the rat ear, and dysplasia, polyp formation and squamous cell carcinomas (SCC). Of 152 mice treated, 88 remained after 30 injections, and 10 out of a total of 14 tumours developed after 30 treatments. Perianal SCC without definite perianal gland association developed in 2 other animals.