Melanoma is an aggressive cancer that begins on the skin surface, or, more rarely in the eye.. Melanoma risk increases with sun exposure. Melanoma is a cancer of the cells that cause the skin to tan when exposed to sunlight by producing pigment. Researchers believe that the sun’s ultraviolet (UV) rays damage genetic material in the skin, causing the melanocytes to grow abnormally.

Melanocytes often clump together creating a mole, or nevus, on the surface of the skin. The majority of these moles are harmless. However, some nevus types can raise a patient’s risk of developing melanoma and any suspicious skin changes should be examined by a physician. Because melanocytes are responsible for a change in the pigment of the skin, melanomas are often brown or black. Sometimes melanocytes fail to make pigment—then melanomas appear as pink or white bumps on the skin.

Melanomas also tend to be asymmetrical (unevenly shaped) with dark, ragged edges.

Melanoma is generally curable if diagnosed right away. But it is much more likely than other types of skin cancer to spread to other parts of the body if it isn’t treated early.

The most common forms of skin cancer are made by other cells and are named for their point of origin—basal cell and squamous cell carcinoma. These cancers rarely spread and are far less dangerous and aggressive than melanoma. As a result, they are treated differently.

While melanomas can be found anywhere on the skin, they show up more often in certain areas of the body. In men, melanomas are generally found on the trunk (chest and back) and in women, on the legs. Melanomas often appear on the neck and face as well. Individuals with darker skin are less likely to develop melanomas in these common sites but are no less likely to develop melanomas on the palms of the hands, the soles of the feet, or inside the oral or genito-anal cavities. These sites account for more than half of all melanomas in African Americans but fewer than one in ten melanomas in Caucasians.