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Last Updated: Mar 1, 2019


Melanoma is a potentially lethal form of skin cancer that originates in melanocytes - cells in the epidermis that produce skin pigment (melanin). Cancer cells are called malignant because they multiply uncontrollably and form destructive growths (tumors).

Melanoma is the most aggressive form of skin cancer and the most likely type to spread (metastasize) to distant organs. Small, early melanomas are highly curable, but advanced metastatic disease is often fatal.

In the United States, the incidence of melanoma is substantially increasing in both men and women. Melanoma usually occurs in adults and less commonly in children or adolescents; however, tanning and sunburns during childhood and adolescence markedly increase a person’s risk of developing melanoma later in life.

Causes and Risk Factors

Illustrated skin cross-section showing epidermis, dermis and subcutis

Exposure to ultraviolet radiation from the sun and tanning beds is the primary cause of melanoma. Individuals with fair skin have a higher risk for melanoma, but the disease can also arise in people with dark skin.

Melanoma can occur spontaneously or arise in an existing mole that changes in size and appearance. Melanoma may develop in any place in the body where melanocytes exist, including the eyes and digestive tract.

Risk Factors For Melanoma:


In women, melanoma most often occurs on the arms or legs; in men the condition often develops on the trunk, head, or neck. The most common signs of melanoma are unusual changes in the size, shape, or color of a mole, including darkening, discoloration, itching, enlargement, and bleeding.Pictures illustrate the ABCD rules for melanoma identification

ABCDE, a mnemonic for early signs of melanoma in a mole, stands for:

Satellite moles, new moles that develop close to a pre-existing mole, often occur with melanoma. Bleeding and ulceration of an abnormal mole are late signs of the disease.


Early melanoma is often extremely difficult to distinguish from benign pigmented moles. Suspicious lesions must be biopsied in a procedure that involves cutting out the abnormal tissue and a portion of surrounding normal tissue for examination under a microscope.

The extent (stage) of the disease determines a patient’s treatment, prognosis, and likelihood of recurrence. The stage is determined by:

Early stage melanoma is highly curable; however, more advanced stages are more difficult to treat. Metastatic melanoma, which most commonly spreads to the liver and lungs, has a high mortality rate.

For staging purposes, computed tomography (CT) provides a series of detailed images of various organs and tissues to detect metastases. Positron emission tomography scan (PET scan) may show evidence of tumor cells at distant sites in the body. Magnetic resonance imaging (MRI) may also be obtained to provide additional images.



Sun exposure is the primary preventable risk factor for melanoma. The skin should be protected by the avoidance of sun exposure between 10 am and 3 pm (the hours of highest ultraviolet radiation intensity). Sunscreen with sun protection factor (SPF) 30 or higher should be applied to exposed skin. Sunglasses, wide-brimmed hats, and protective clothing also provide essential skin protection. Children must be protected from sunburns to decrease their risk of developing melanoma in adulthood, and tanning beds should be avoided.

Early Detection

Self-examination of the skin can detect early signs of melanoma, such as new skin lesions or changes in the size, shape, and color of existing moles. A physician should evaluate any suspicious skin lesions. Individuals with risk factors for skin cancer should undergo an annual complete skin examination by a physician.


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.