amelanotic melanoma

melanoma /mel·a·no·ma/ (mel″ah-no´mah) a tumor arising from the melanocytic system of the skin and other organs; used alone, it refers to malignant m..

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acral-lentiginous melanoma  an irregular, enlarging black macule with a prolonged noninvasive stage, occurring chiefly on the palms and soles; it is the most common type of melanoma in nonwhite persons.

amelanotic melanoma  an unpigmented malignant melanoma.

juvenile melanoma  spindle and epithelioid cell nevus.

lenti´go malig´na melanoma  a cutaneous malignant melanoma arising in the site of a preexisting lentigo maligna, occurring on sun exposed areas, particularly of the face.

malignant melanoma  a malignant tumor usually developing from a nevus or lentigo maligna and consisting of black masses of cells with a marked tendency to metastasis.

nodular melanoma  a type of malignant melanoma without a perceptible radial growth phase, usually occurring on the head, neck, or trunk as a uniformly pigmented, elevated, bizarrely colored, rapidly enlarging nodule that ulcerates.

ocular melanoma  malignant melanoma arising from the structures of the eye, frequently metastasizing and rapidly causing death.

subungual melanoma  acral-lentiginous melanoma in the nail fold or bed.

superficial spreading melanoma  malignant melanoma characterized by a period of radial growth atypical of epidermal melanocytes, which may be followed by invasive growth or may regress; it usually occurs as a small pigmented macule or papule with irregular outline on the lower leg or back.

uveal melanoma  ocular melanoma consisting of overgrowth of uveal melanocytes.

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amelanotic melanoma,

a melanoma that lacks melanin. See also melanoma.

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melanoma

a tumor arising from melanocytes, dendritic cells of neuroectodermal origin, or melanoblasts. They are most common in the skin, eye and oral cavity of dogs and aged gray horses, but occur occasionally as congenital lesions in pigs, goats and cattle. An inherited, malignant melanoma is recorded in swordtail-platyfish hybrids.

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amelanotic melanoma

one containing little or no melanin.

benign m's

usually pigmented plaques or nodules. Those with junctional activity are analogous to the human compound junctional nevus.

congenital melanoma of pigs

a single or multiple pigmented tumor of the skin or viscera that grows slowly and may metastasize. Spontaneous regression is common. An inherited form seen in Sinclair miniature pigs.

dermal melanoma

a tumor which arises from rests of melanocytes in the dermis, remnants of neural crest precursors. Pigmentation is variable. It is usually benign.

malignant melanoma

a malignant, rapidly growing, frequently ulcerated mass, consisting of either spindle cells or epithelioid cells or a mixture of the two, with a marked tendency to metastasize. The tumor cells may or may not (amelanotic) be pigmented. Although melanomas in pigs and cattle are usually benign and are not treated, those in horses, dogs, cats and occasional cases in sheep, goats and pigs are malignant. Called also nevocarcinoma.

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amelanotic melanoma

Dermatology A rare, poorly differentiated form of melanoma, which occurs in Pts with a previous pigmented melanoma. See Melanoma, Regression.