Diffuse Melanosis in Malignant Melanoma

Abstract

The clinical events and findings by light and electron microscopy are presented of a patient with malignant melanoma, primary in the skin, widely metastasized, and terminally associated with diffuse melanosis and melanuria. A marked increase in pigment was found in epidermis and dermis. The most likely explanation for the dermal melanosis is that it represents pigment produced by distant malignant melanoma cells. This pigment is secondarily deposited in the skin via the circulation. Hyperpigmentation of the epidermis in this patient probably arose from a different mechanism such as by increased melanogenesis by epidermal melanocytes or by decreased epidermopoiesis.