Skin melanoma induced by 7,12-dimethylbenzanthracene in albino guinea pigs and its similarities to skin melanoma of humans.

A model for a metastasizing melanoma was developed, and its characteristics were established. Sixty-five albino guinea pigs were painted with 7,12-dimethylbenzanthracene in acetone. There was evidence that, after 18 months, 40% of the animals developed melanomas. Melanomas arose by a malignant transformation of junctional nevus cells and/or by transformation of amelanotic melanocytes. Metastases to the skin and internal organs were multiple and eventually fatal for the animals. Histology and electron microscopy of induced melanomas were reviewed in detail. Clinical and histological events leading to development of melanoma in albino guinea pigs were found to be similar to human melanomas in a number of aspects. Fragments of melanomas were successfully transplanted to "nude" mice and healthy albino guinea pigs. The described model could be used for study of the various cellular and tissue events which precede nevus, lentigo maligna, and melanoma formation. It could also be useful in studying carcinogenic potential, for studying development of metastases, and presumably for trials of treatment.