Nude mouse model of the melanosis syndrome.

The occurrence of diffuse hyperpigmentation secondary to a xenografted human malignant melanoma was observed in nude mice. The patient from whom this cell line was established developed cutaneous hyperpigmentation after his disease became disseminated. Light and electron microscopy studies were performed on skin and organ biopsy specimens from the hyperpigmented mice. These studies indicated that this melanoma-associated melanosis was secondary to the release of pigment granules from the xenografted tumors and to the uptake of these granules by macrophages throughout the body, including those located in the dermis.