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..
Melanoma
melanoma
melanoma (mel´
nō´m),
melanoma
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.
mel·a·no·ma (m l  -n  m)n. pl. mel·a·no·mas or mel·a·no·ma·ta (-m -t) A dark-pigmented, malignant, frequently widely metastasizing tumor arising from a melanocyte and occurring most commonly in the skin. Also called malignant melanoma, melanoblastoma, melanocarcinoma, melanotic carcinoma. |
Melanoma
The most dangerous form of skin cancer. It should not be treated with cryotherapy, but should be removed surgically instead.
Mentioned in: Cryotherapy, Sunscreens
melanoma
[mel′ənō′mə] pl., melanomas, melanomata
Etymology: Gk, melas + oma, tumor
any of a group of malignant neoplasms that originate in the skin and that are composed of melanocytes. A melanocytic nevus may be acquired or congenital. The congenital melanocytic nevus is regarded as more likely to develop into a malignant melanoma, primarily because of its larger size. Smaller melanomas tend to develop from a pigmented nevus over several months or years. They may be sporadic and occur most commonly in fair-skinned people having light-colored eyes. A previous sunburn increases a person's risk. Any black or brown spot having an irregular border; pigment appearing to radiate beyond that border; a red, black, and blue coloration observable on close examination; or a nodular surface is suggestive of melanoma and is usually excised for biopsy. Melanomas are most commonly located on the upper back and lower legs of fair-skinned individuals and on the palms of the hands and insoles of the feet of dark-skinned individuals. Melanomas may metastasize and are among the most malignant of all skin cancers. Prognosis depends on the kind of melanoma; its size, depth of invasion, and location; and the age and condition of the patient. Because of the occurrence of melanomas and melanocytic nevi in certain families, a familial atypical mole and melanoma syndrome has been designated. It is defined by the occurrence of melanoma in one or more first- or second-degree relatives, a large number of moles, and moles that demonstrate certain cellular features. Patients with the syndrome have a high lifetime risk of development of melanoma. Kinds of melanoma are amelanic melanoma, benign juvenile melanoma, lentigo maligna melanoma, nodular melanoma, primary cutaneous melanoma, and superficial spreading melanoma. Compare blue nevus. See also Hutchinson's freckle.
melanoma (mel´
nō´m),n a malignant epithelial neoplasm characterized by pigment-producing cells. It usually is dark in color but may be amelanotic, i.e., free of pigment. It can occur in skin as well as the oral cavity, where it usually would be a late finding. It can occur at the site of a mole (mainly) or another site.
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.
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.
melanoma
Tumour derived from cells that are capable of forming melanin.
choroidal melanoma The most common primary malignant tumour in the eye in adults. It appears under ophthalmoscopic examination as a pigmented, elevated mass, usually brown in colour and sometimes with orange pigment (lipofuscin). The tumour may cause a decrease in vision or brief 'balls of light' moving cross the visual field, or be asymptomatic, depending on its size or location. The condition is typically unilateral. Differential diagnosis with retinal detachment or choroidal naevus is essential. Treatment may include radiotherapy or photocoagulation, or enucleation if the melanoma is large and vision irreversibly lost. Syn. malignant melanoma of the choroid.
iris melanoma A pigmented lesion, which is easily seen on the surface of the iris. It alters the colour of the iris and may distort the shape of the pupil. A dilated episcleral vessel running towards the tumour may be present. There may be a localized cataract where the tumour is in contact with the lens and secondary glaucoma may develop if the tumour has spread to the angle of the anterior chamber. The tumour arises from the iris stroma and is composed of epitheloid or spindle cells, or a mixture of both. It is almost always unilateral and most commonly found in white patients with light irides. It is thought to originate from a previous pigmented naevus. If the tumour is found to enlarge it will usually be excised surgically. (Fig. M7) See iris naevus.
uveal melanoma Tumour which may be located in the choroid, the ciliary body or the iris. Choroidal melanomas make up about 85% of the total, ciliary body about 10% and iris about 5%. Although uveal melanomas can occur at any age, the majority of patients are beyond the age of 40 years. Uveal melanomas can metastasize, especially choroidal melanomas. Diagnosis is best achieved with a B-scan ultrasound examination. The patient must be referred to an ocular oncologist without delay. See ultrasonography.
choroidal melanoma The most common primary malignant tumour in the eye in adults. It appears under ophthalmoscopic examination as a pigmented, elevated mass, usually brown in colour and sometimes with orange pigment (lipofuscin). The tumour may cause a decrease in vision or brief 'balls of light' moving cross the visual field, or be asymptomatic, depending on its size or location. The condition is typically unilateral. Differential diagnosis with retinal detachment or choroidal naevus is essential. Treatment may include radiotherapy or photocoagulation, or enucleation if the melanoma is large and vision irreversibly lost. Syn. malignant melanoma of the choroid.
iris melanoma A pigmented lesion, which is easily seen on the surface of the iris. It alters the colour of the iris and may distort the shape of the pupil. A dilated episcleral vessel running towards the tumour may be present. There may be a localized cataract where the tumour is in contact with the lens and secondary glaucoma may develop if the tumour has spread to the angle of the anterior chamber. The tumour arises from the iris stroma and is composed of epitheloid or spindle cells, or a mixture of both. It is almost always unilateral and most commonly found in white patients with light irides. It is thought to originate from a previous pigmented naevus. If the tumour is found to enlarge it will usually be excised surgically. (Fig. M7) See iris naevus.
uveal melanoma Tumour which may be located in the choroid, the ciliary body or the iris. Choroidal melanomas make up about 85% of the total, ciliary body about 10% and iris about 5%. Although uveal melanomas can occur at any age, the majority of patients are beyond the age of 40 years. Uveal melanomas can metastasize, especially choroidal melanomas. Diagnosis is best achieved with a B-scan ultrasound examination. The patient must be referred to an ocular oncologist without delay. See ultrasonography.
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Fig. M7 Iris melanoma of the left eye
melanoma
Malignant melanoma Dermatology A tumor which comprises 1-3% of all new cancers–18,000/yr, causes 6500 deaths/yr–US, most age 30–50; the incidence of melanoma is ↑ at ± 7%/yr, and now affects 9/105,
primarily head & neck in ♂ and 12/105, primarily the legs in ♀; melanoma is rare, but more aggressive in chidren Risk factors Giant congential melanocytic nevus, dysplastic nevus, xeroderma pigmentosum, immunodeficiency, moles with
persistent pigment changes–especially > age 15, large or irregularly pigmented lesions, familial moles, congenital moles; white–12-fold greater risk than blacks, previous melanoma, melanoma in 1st-degree relative,
immunosuppression, photosensitivity, ↑ sun exposure; ocular melanomas may not ↑ melanoma risk Site of metastasis Liver, lung, intestine, pancreas, adrenal, heart, kidney, brain, spleen, thyroid. See Acral lentiginous melanoma, Amelanotic melanoma, Congenital melanoma, Dysplastic nevus syndrome, Lentigo maligna melanoma, Nodular melanoma, Ocular melanoma, Premalignant melanoma, Pseudomelanoma, Radial growth phase melanoma, Superficial spreading melanoma, Thin melanoma, Vertical growth phase melanoma, Vertical growth phase melanoma.
Melanoma
Stage I Confined to the epidermis and/or the upper dermis, and measures ≤ 1.5 mm thick
Stage II 1.5 mm to 4 mm thick, spread to lower dermis, but not beyond or to adjacent lymph nodes
Stage III Any of the following: (1) > 4 mm thick; (2) Spread beyond the skin; (3) Satellite lesions within 2 cms of the original tumor; or (4) Spread to nearby lymph nodes or satellite lesions between original and regional lymph nodes
Stage IV Metastases to other organs or to lymph nodes far from the original lesion
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