Melanoma is type of skin cancer. It occurs when the melanocyte cells in the skin become cancerous.

Melanoma_NCIMelanoma is most common in adults, but it is sometimes found in children and adolescents

Melanocytes are found throughout the lower part of the epidermis. They make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment, causing the skin to tan, or darken.

The skin has 2 main layers: the epidermis (upper or outer layer) and the dermis (lower or inner layer). Melanocytes are in the layer of basal cells at the deepest part of the epidermis.

When melanoma starts in the skin, the disease is called cutaneous melanoma. Melanoma may also occur in mucous membranes (thin, moist layers of tissue that cover surfaces such as the lips). When melanoma occurs in the eye, it is called intraocular or ocular melanoma.

Melanoma is more aggressive than basal cell skin cancer or squamous cell skin cancer, which are referred to as nonmelanoma skin cancer.

Melanoma can occur anywhere on the body.
In men, melanoma is often found on the trunk (the area from the shoulders to the hips) or the head and neck. In women, melanoma forms most often on the arms and legs.

Unusual moles, exposure to sunlight, and health history can affect the risk of melanoma.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for melanoma include the following:

Fair skin that freckles and burns easily, does not tan, or tans poorly.

Blue or green or other light-colored eyes.

Red or blond hair.

Being white or having a fair complexion increases the risk of melanoma, but anyone can have melanoma, including people with dark skin.