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a tumor arising from the melanocytic system of the skin and other organs. When used alone, the term refers to malignant melanoma.
acral-lentiginous melanoma an uncommon type of melanoma, although it is the most common type seen in nonwhite individuals, occurring chiefly on the palms and soles, and sometimes involving mucosal surfaces, such as the vulva or vagina. The characteristic lesion is an irregular, enlarging black macule, which has a prolonged noninvasive stage.
juvenile melanoma spindle and epithelioid cell nevus.
lenti´go malig´na melanoma a cutaneous malignant melanoma found most often on the sun-exposed areas of the skin, especially the face. It begins as a circumscribed macular patch of mottled pigmentation, showing shades of dark brown, tan, or black (lentigo maligna or melanotic freckle of Hutchinson), and enlarges by lateral growth before dermal invasion occurs. This type seems to be the least aggressive form of malignant melanoma.
malignant melanoma a malignant skin tumor, usually developing from a nevus and consisting of dark masses of cells with a marked tendency to metastasis. It is not common, but its incidence is increasing and it is the most aggressive type of skin cancer. It arises from pigment- (melanin-) producing cells and varies in course and prognosis according to type; types include superficial spreading melanoma, nodular malignant melanoma, and lentigo maligna melanoma. In general, the superficial lesions can be cured by surgical excision of the mole and adjacent tissues. Deeper lesions tend to metastasize rapidly through the lymphatic and circulatory systems. In some cases the condition has a genetic component. Early detection and skin protection are key in its control.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.