Melanoma is caused by changes in skin cells called melanocytes. These cells make a skin color pigment called melanin. Melanin is responsible for skin and hair color.
Melanoma can appear on normal skin. Or, it can begin as a mole or other area that then changes in appearance. Some moles that are present at birth may develop into melanomas.
There are four major types of melanoma:
- Superficial spreading melanoma is the most common type. It is usually flat and irregular in shape and color, with different shades of black and brown. It is most common in Caucasians.
- Nodular melanoma usually starts as a raised area that is dark blackish-blue or bluish-red. Some do not have any color (amelanotic melanoma).
- Lentigo maligna melanoma usually occurs in the elderly. It is most common in sun-damaged skin on the face, neck, and arms. The abnormal skin areas are usually large, flat, and tan with areas of brown.
- Acral lentiginous melanoma is the least common form. It usually occurs on the palms, soles, or under the nails. It is more common in African Americans.
In rare cases, melanomas appear in the mouth, iris of the eye, or retina at the back of the eye. These may be found during dental or eye exams. In very rare cases, a melanoma develops in the vagina, esophagus, anus, urinary tract or small intestine.
Melanoma is not as common as other types of skin cancer, such as basal cell cancer. But more and more persons are developing melanoma.
The risk of developing melanoma increases with age, though it can also be seen in young people.
You are more likely to develop melanoma if you:
- Have fair skin, blue or green eyes, or red or blond hair
- Live in sunny climates or at high altitudes
- Spent a lot of time in high levels of strong sunlight because of a job or other activities
- Have had one or more blistering sunburns during childhood
- Use tanning devices
Other risk factors include:
- Close relatives with melanoma
- Certain types of moles (atypical or dysplastic) or many birthmarks
- Weakened immune system due to disease or medication