Malignant melanoma

Alternative names:

acral lentiginous melanoma; cancer of the skin (malignant melanoma); lentigo maligna melanoma; melanoma - acral lentiginous; melanoma - lentigo maligna; melanoma - malignant; melanoma - nodular; melanoma - superficial spreading; nodular melanoma; skin cancer - malignant melanoma; superficial spreading melanoma

Definition:

A malignant skin tumor that involves the skin cells that produce pigment (melanin).

Causes, incidence, and risk factors:

Any change in an existing wart, mole, or other skin lesion, or development of a new growth that ulcerates and does not heal well, could indicate the development of a skin cancer. Skin cancer has a high cure rate if treated early, but neglect can allow the cancer to spread, causing disability or death.

Malignant melanoma is the most deadly form of skin cancer. It is also the least common. However, the incidence has doubled in the United States in the last 20 years. It is the leading cause of death from skin disease. Approximately 35,000 cases of malignant melanoma occurred in the United States in 1990, making it one of the most common forms of cancer that year. Melanoma is the number one cancer in young women under age 35. It can affect any age, with a recent trend toward discovery of the tumor at increasingly younger ages. Men have a higher rate of death from malignant melanoma than women. Deaths from complications of malignant melanoma are increasing at a faster rate than deaths from any other form of cancer except lung cancer.

Malignant melanoma involves cancerous changes to the skin cells that produce the skin's pigment, melanin. About 70% of melanomas appear on normal skin, and 30% occur in nevi (moles) or other lesions that have changed in appearance. Rarely, congenital birthmarks such as blue nevi and giant nevi may develop melanomas. The tumor may develop quickly and initially spreads to adjacent skin. It is highly curable in this phase. Later, it spreads downward to deeper skin areas and may spread (metastasize) to the internal structures and organs. This phase has a much lower cure rate.

Superficial spreading melanoma is a form of malignant melanoma that accounts for about 70% of cases of this disorder. It may strike at any age and is most common in Caucasians.

Nodular melanoma accounts for about 15% of cases. It may include ulcerations that never heal. It can develop anywhere on the body, usually between the ages of 20 and 60.

Acral lentiginous melanoma occurs in about 10% of cases of melanoma. It is most common in the elderly and always occurs on the palms, soles, or mucosal surfaces.

Lentigo maligna melanoma occurs in about 5% of cases, usually in the elderly. It is most common in sun damaged skin on the head, neck, and arms.

Sunlight (ultraviolet light) is the chief cause of all skin cancers including melanomas.