Melanoma is the most serious type of cancer of the skin. Each year in the United States, more than 53,600 people learn they have melanoma.

In some parts of the world, especially among Western countries, melanoma is becoming more common every year. In the United States, for example, the percentage of people who develop melanoma has more than doubled in the past 30 years.

How Melanoma Develops

Melanoma occurs when melanocytes (pigment cells) become malignant. 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.

Melanocytes – 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.

Moles – 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.

Types of Melanoma – Most pigment cells are in the skin; when melanoma starts in the skin, the disease is called cutaneous melanoma. Melanoma may also occur in the eye (ocular melanoma or intraocular melanoma). Rarely, melanoma may arise in the meninges, the digestive tract, lymph nodes, or other areas where melanocytes are found.

Signs and Symptoms

Often, the first sign of melanoma is a change in the size, shape, color, or feel of an existing mole. Most melanomas have a black or blue-black area. Melanoma also may appear as a new mole. It may be black, abnormal, or “ugly looking.”

If you have a question or concern about something on your skin, see your doctor. Thinking of “ABCD” can help you remember what to watch for:

• Asymmetry – The shape of one half does not match the other.
• Border – The edges are often ragged, notched, blurred, or irregular in outline; the pigment may spread into the surrounding skin.
• Color – The color is uneven. Shades of black, brown, and tan may be present. Areas of white, grey, red, pink, or blue also may be seen.
• Diameter – There is a change in size, usually an increase. Melanomas are usually larger than the eraser of a pencil (1/4 inch or 5 millimeters).

Melanomas can vary greatly in how they look. Many show all of the ABCD features. However, some may show changes or abnormalities in only one or two of the ABCD features.

Talk to Your Doctor

Changes in the skin, such as a change in a mole, should be reported to the health care provider right away. The person may be referred to a dermatologist, a doctor who specializes in diseases of the skin.

Treatment

People with melanoma may have surgery, chemotherapy, biological therapy, or radiation therapy. Patients may have a combination of treatments.

People with melanoma are often treated by a team of specialists. The team may include a dermatologist, surgeon, medical oncologist, radiation oncologist, and plastic surgeon.

Metastasis

When melanoma spreads, cancer cells may show up in nearby lymph nodes. Groups of lymph nodes are found throughout the body. Lymph nodes trap bacteria, cancer cells, or other harmful substances that may be in the lymphatic system. If the cancer has reached the lymph nodes, it may mean that cancer cells have spread to other parts of the body such as the liver, lungs, or brain. In such cases, the cancer cells in the new tumor are still melanoma cells, and the disease is called metastatic melanoma, not liver, lung, or brain cancer.

Know Your Risk and Get Screened

Melanoma is one of the most common cancers. The chance of developing it increases with age, but this disease affects people of all ages. It can occur on any skin surface. In men, melanoma is often found on the trunk (the area between the shoulders and the hips) or the head and neck. In women, it often develops on the lower legs. Melanoma is rare in black people and others with dark skin. When it does develop in dark-skinned people, it tends to occur under the fingernails or toenails, or on the palms or soles. People who have had melanoma have a high risk of developing a new melanoma. People at risk for any reason should check their skin regularly and have regular skin exams by a health care provider.

Melanoma can be cured if it is diagnosed and treated when the tumor is thin and has not deeply invaded the skin. However, if a melanoma is not removed at its early stages, cancer cells may grow downward from the skin surface and invade healthy tissue. When a melanoma becomes thick and deep, the disease often spreads to other parts of the body and is difficult to control.

To Learn More

• Skin Cancer Symptoms and Tests
• Treatments for Skin Cancer
• Mohs Surgery – A Treatment for Skin Cancer
• Back to Skin Cancer Overview

For more information:

Go to the Skin Cancer health topic.