Melanoma is a malignant form of skin cancer that occurs in cells called melanocytes, which produce pigments that give skin its color. Melanoma usually appears as an irregular brown, black and/or red spot, or an existing mole that begins to change color, size or shape. While melanoma only represents about 3 percent of all skin cancers, it has the highest death rate of all types, and is more likely to metastasize (spread).
Melanoma appears most frequently on the trunk area in fair-skinned men and on the lower leg in fair-skinned women. In dark-skinned people, melanoma appears most frequently on the palms, the soles of the feet and the skin under nails. If caught early, melanoma is potentially curable.
There are four major types of cutaneous melanoma: Superficial spreading melanoma is the most common form of the disease, responsible for about 70 percent of cases. It generally originates in a pre-existing mole.
Nodular melanoma is the second most common, responsible for 15 to 30 percent of cases. Nodular melanomas are more aggressive and usually develop more rapidly than superficial melanomas.
Lentigo maligna melanoma appears as large, flat lesions most commonly found on the faces of light-skinned women over the age of 50. This form of melanoma, responsible for about 4 percent to 10 percent of cases, has a lower risk of metastasis than other types.
Acral lentiginous melanoma occurs on the palms, soles of the feet or beneath the nail beds. They account for only 2 percent to 8 percent of melanomas in fair-skinned patients, but up to 60 percent of melanomas in darker-skinned patients. Acral lentiginous melanomas are extremely aggressive and large, with an average diameter of three centimeters.
Mucosal melanomas are rare, making up only about 1 percent of all diagnosed melanoma cases. This disease occurs in mucosal tissue, which lines body cavities and hollow organs. The most common sites for mucosal melanoma are the head and neck region (including the nasal cavity, mouth and esophagus), as well as the rectum, urinary tract and vagina. Mucosal melanomas can be very hard to detect, and even when diagnosed and treated, the outlook is poor.
Because the eyes contain melanocytes, or pigment-producing cells, they can be susceptible to melanoma. Read more about the two types of ocular melanoma:
- Uveal Melanoma
- Conjunctival Melanoma
Symptoms of skin cancer vary from person to person and may include a:
- Change on the skin, such as a new spot or one that changes in size, shape or color
- Sore that doesn’t heal
- Spot or sore that changes in sensation, itchiness, tenderness or pain
- Small, smooth, shiny, pale or waxy lump
- Firm red lump that may bleed or develops a crust
- Flat, red spot that is rough, dry or scaly
Many of these symptoms are not cancer, but if you notice one or more of them for more than two weeks, see your doctor.