Melanoma facts

  • Melanoma is a skin cancer that begins in cells called melanocytes.

  • Melanocytes can grow together to form benign (not cancerous) moles.

  • A change in size, shape, or color of a mole can be a sign of melanoma. Other symptoms of a malignant (cancerous) mole include itching, bleeding, and scaliness.

  • Melanoma can be cured if detected early before spread (metastasis) to other areas of the body.

  • Diagnosis of melanoma is confirmed with a biopsy of the abnormal skin.

  • To determine the stage of the melanoma, the doctor will need to determine the thickness of the melanoma and check if the melanoma has spread.

  • Treatment of melanoma depends on the extent of disease and the patient's age and general health.

  • The prognosis of melanoma depends upon a melanoma's thickness, the depth of penetration of the skin, the extent to which it has spread, and certain characteristics of the tumor such as its mitotic rate and the presence of ulceration.

  • Sun exposure can cause skin damage that can lead to melanoma.

What is melanoma?

Melanoma is a type of skin cancer. It begins in cells in the skin called melanocytes. To understand melanoma, it is helpful to know about the skin and about melanocytes -- what they do, how they grow, and what happens when they become cancerous.

The skin

The skin is the body's largest organ. It protects against heat, sunlight, injury, and infection. It helps regulate body temperature, stores water and fat, and produces vitamin D.

The skin has two main layers:  the outer epidermis and the inner dermis.

  • The epidermis is mostly made up of flat, scalelike cells called squamous cells. Round cells called basal cells lie under the squamous cells in the epidermis. The lower part of the epidermis also contains melanocytes.

  • The dermis contains blood vessels, lymph vessels, hair follicles, and glands. Some of these glands produce sweat, which help regulate body temperature. Other glands produce sebum, an oily substance that helps keep the skin from drying out. Sweat and sebum reach the skin's surface through tiny openings called pores.

Melanocytes and moles

Melanocytes produce melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes produce more pigment, causing the skin to tan, or darken.

Sometimes, clusters of melanocytes and surrounding tissue form noncancerous growths called moles. (Doctors also call a mole a nevus; the plural is nevi.) Moles are very common. Most people have between 10 and 40 moles. Moles may be pink, tan, brown, or a color that is very close to the person's normal skin tone. People who have dark skin tend to have dark moles. Moles can be flat or raised. They are usually round or oval and smaller than a pencil eraser. They may be present at birth or may appear later on -- usually before age 40. They tend to fade away in older people. When moles are surgically removed, they normally do not return.


Illustration of Normal Skin

Learn about Senator John McCain's history of melanoma, a deadly form of skin cancer.

Melanoma Skin Cancer of U.S. Senator John McCain

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

In August of 2000, U.S. senator and presumptive Republican presidential nominee John McCain was found to have a dangerous form of skin cancer, melanoma, for the second time. The senator had a superficial (meaning less dangerous because it has not invaded deeply into the tissues) melanoma diagnosed in 1993. Melanoma is the most dangerous form of skin cancer and is frequently associated with prolonged exposure of the skin to sunlight.

The cancer identified in 2000, located on the left side of his face, had penetrated the skin more deeply than the superficial cancer removed in 1993. The cancer diagnosed in 2000 was removed by a surgical procedure that also included removal and examination of multiple lymph nodes to determine the extent of the spread of the cancer. His staff reported at the time that there was no evidence of spread of the cancer. According to press reports, McCain has also had two more superficial melanomas removed since his surgery in 2000.

Melanoma can occur on any skin surface. In men, it is often found on the trunk (the area from the shoulders to the hips) or the head and neck. In women, melanoma often develops on the lower legs or the trunk. Melanoma is rare in people with deeply pigmented skin. When it does develop in dark-skinned people, it tends to occur under the fingernails or toenails, or on the palms of the hands or soles of the feet. Melanoma affects people of all age groups, but the chance of developing this disease increases with age.

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