Sequential pathological study on chemically-Induced skin tumours in rats

Dermal application of 5 m mol dimethylbenz(a) anthracine DMBA)fortnightly over the hind back of Wister rats could cause roughness and thickening of skin during 10–12^th weeks, dermal hyperplasia (12^th weeks), severe dermal hyperplasia (14–18^th weeks), skin-papilloma (20–26^th weeks), papillary carcinoma (28–38^th weeks)and full blown squamous cell carcinoma (40^th weeks onwards) with metastasis in lungs. In addition, sebaceous gland carcinoma (43^rd weeks), sweat gland adenocarcinoma (44^th weeks) and various connective tissue tumours, viz., fibrosarcoma, hemangiopericytoma, dermal neuro-fibroma were encountered. Skin neoplasms could be induced by DMBA alone and croton oil failed to promote cancer progression. The skin alterations and various tumours observed were described and discussed.