Melanoma is the most dangerous type of skin cancer. It is the leading cause of death from skin disease.
It involves cells called melanocytes, which produce a skin pigment called melanin. Melanin is responsible for skin and hair color.
Melanoma can also involve the colored part of the eye. For information about that form of melanoma, see melanoma of the eye.
Skin cancer - melanoma
Causes, incidence, and risk factors
Melanoma can appear on normal skin, or it may begin as a mole or other area that has changed 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 of melanoma. It is usually flat and irregular in shape and color, with different shades of black and brown. It may occur at any age or body site, and is most common in Caucasians.
- Nodular melanoma usually starts as a raised area that is dark blackish-blue or bluish-red. However, some do not have any color.
- 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 of melanoma. It usually occurs on the palms, soles, or under the nails and is more common in African Americans.
Rarely, melanomas appear in the mouth, iris of the eye, or retina at the back of the eye. They may be found during dental or eye examinations. Although very rare, melanoma can also develop in the vagina, esophagus, anus, urinary tract, and small intestine.
Melanoma can spread very rapidly. Although it is less common than other types of skin cancer, the rate of melanoma is steadily increasing. It is the leading cause of death from skin disease.
The risk of developing melanoma increases with age. However, the disease also frequently affects young, otherwise healthy people.
The development of melanoma is related to sun exposure or ultraviolet radiation, particularly among people with fair skin, blue or green eyes, and red or blond hair.
Risks for melanoma include the following:
- Living in sunny climates or at high altitudes
- Long-term exposure to high levels of strong sunlight, because of a job or other activities
- One or more blistering sunburns during childhood
- Use of tanning devices
Other risk factors include:
- Close relatives with a history of melanoma
- Exposure to chemicals that can cause cancer, such as arsenic, coal tar, and creosote
- Presence of certain types of moles (atypical dysplastic) or multiple birthmarks
- Weakened immune system due to AIDS, some leukemias, organ transplant, medications used to treat illnesses such as rheumatoid arthritis
The primary symptom of any skin cancer is usually a mole, sore, lump, or growth on the skin. Any change in appearance of a pigmented skin sore over time is a warning sign. Also, watch for any bleeding from a skin growth.
The ABCD system may help you remember features that might be symptoms of melanoma:
- Asymmetry: One half of the abnormal area is different from the other half.
- Borders: The lesion or growth has irregular edges.
- Color: Color changes from one area to another, with shades of tan, brown, or black (sometimes white, red, or blue). A mixture of colors may appear within one sore.
- Diameter: The trouble spot is usually (but not always) larger than 6 mm in diameter -- about the size of a pencil eraser.
The key to treating melanoma is recognizing symptoms early. You might not notice a small spot of concern if you don't look carefully, so perform thorough self-examinations monthly, and schedule a formal skin exam with a dermatologist yearly.
Signs and tests
If you notice any suspicious skin markings, see your health care provider as soon as possible.
Your health care provider will look at the appearance of the growth, sore, or lump. A biopsy may be used to confirm the diagnosis. The biopsy may involve removing a small area of a growth, or the entire growth.
A procedure called sentinel lymph node (SLN) biopsy may be used for some people with melanoma to see if the cancer has spread to nearby lymph nodes.
Once melanoma has been diagnosed, CT scans or other types of x-ray tests may be done to see if the cancer has spread.
The cancerous skin cells and some normal tissue that surrounds the cancer will need to be surgically removed. How much normal tissue is removed depends mostly on how deep the melanoma has grown.
If the cancer has spread to nearby lymph nodes, these lymph nodes may also need to be removed. Treatment with interferon after surgery may be useful for these patients.
For patients with melanoma that has spread beyond the skin and nearby lymph nodes to other organs, treatment is more difficult. At this point, melanoma is usually not curable. Treatment is usually directed at shrinking the tumor and improving symptoms:
- Chemotherapy is often used to treat melanoma that has returned or spread.
- Medications such as interferon or interleukin, which boost the immune system to fight the cancer, may be useful in addition to chemotherapy and surgery. This kind of treatment is called immunotherapy. However, interferon has many side effects and can be difficult to tolerate.
- Radiation treatments may be used to relieve pain or discomfort caused by cancer that has spread.
- Cancer that has spread elsewhere in the body is sometimes removed with surgery to relieve pain or discomfort.
Patients with high-risk melanomas may consider enrolling in clinical trials. These are research studies of new medications or other treatments.
For additional resources, see cancer support group.
Treatment success depends on many factors, including the patient's general health and whether the cancer has spread to the lymph nodes or other organs.
If caught early, some melanomas can be cured. Deeper tumors are more likely to come back. If the skin cancer is deeper than 4 mm or the lymph nodes have cancer, there is a high risk of the cancer spreading to other tissues and organs. If the cancer has spread to the lymph nodes, there is a greater chance that the melanoma will come back.
For patients with melanoma that has spread beyond the skin and nearby lymph nodes to other organs, treatment is more difficult. At this point, melanoma is usually not curable.
Complications of melanoma include the following:
- Damage to deep tissue
- Side effects of treatment
- Hair loss
- Spread to other organs
Calling your health care provider
Call your health care provider if you notice any symptoms of melanoma, particularly the following:
- If any existing skin growth changes in color, size, or texture
- If an existing lesion develops pain, swelling, bleeding, or itching
Anyone who has recovered from melanoma should carefully follow preventive guidelines and watch closely for suspicious marks. Your risk for developing a new melanoma is increased, even if the first one was cured. The disease may return years after the original diagnosis.
The American Cancer Society recommends professional skin examinations every year for people older than 40, and every 3 years for people ages 20 - 40.
Self-examination is also recommended. You should examine your skin once a month, using a mirror to check hard-to-see places. Call your doctor if you notice any suspicious skin changes.
Protect yourself from the sunlight's damaging ultraviolet rays by doing the following:
- Apply a sunscreen with SPF 30 or higher every day (during winter months as well)
- Avoid lying in the sun or using tanning devices
- Minimize sun exposure
- Especially during the summer
- Particularly between the hours of 10:00 a.m. and 4:00 p.m.
- Wear protective clothing, including a hat and sunglasses
Clinical practice guidline for melanoma: NCCN Medical Practice Guidelines and Oncology:V.2.2009. Accessed July 15, 2009.
Goodson AG, Grossman D. Strategies for early melanoma detection: Approaches to the patient with nevi. J Am Acad Dermatol. 2009;60:719-735.
Markovick SN, Erickson LA, Rao RD, Weenig RH, Prockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 1: epidemiology, risk factors, screening, prevention, and diagnosis. Mayo Clin Proc. 2007;82:364-380.
Markovick SN, Erickson LA, Rao RD, Weenig RH, Prockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 2: staging, prognosis, and treatment. Mayo Clin Proc. 2007;82:490-513.
Reviewed By: Jonathan Kantor, MD, North Florida Dermatology Associates, Jacksonville, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.