Melanoma is a type of skin cancer that develops in the cells (melanocytes) that produce melanin, the pigment that gives your skin its color. It is the most dangerous type of skin cancer and is more likely to grow and spread than other types of skin cancer. Melanoma can also form in your eyes and, rarely, inside your body, such as in your nose or throat.

The exact cause of all melanomas isnt clear, but exposure to ultraviolet (UV) radiation from sunlight or tanning lamps and beds increases your risk of developing melanoma. Limiting your exposure to UV radiation can help reduce your risk of melanoma. Melanoma occurs when DNA damage from sunburns or tanning due to UV radiation triggers changes (mutations) in the melanocytes, resulting in uncontrolled cellular growth.

Melanoma can appear as a new mole or an existing mole that changes in size, shape, or color. It can also occur on otherwise normal-appearing skin. Normal moles are generally a uniform color, such as tan, brown, or black, with a distinct border separating the mole from your surrounding skin. Theyre oval or round and usually smaller than 1/4 inch (about 6 millimeters) in diameter, the size of a pencil eraser.

If you have a mole or other spot that looks suspicious, your doctor may remove it and look at it under the microscope to see if it contains cancer cells. This is called a biopsy. Surgery is usually the main treatment for melanoma, and the procedure involves cutting out the cancer and some of the normal skin surrounding it. The amount of healthy skin removed will depend on the size and location of the skin cancer. Typically, surgical excision (removal) of melanoma can be performed under local anesthesia in the dermatologists office. More advanced cases may require other types of treatment in addition to or instead of surgery.