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Definition

Melanoma is a type of skin cancer. It is most common in the skin. However, it can also form in the eyes, digestive system, nails, or lymph nodes.

Melanoma is more likely to spread to other parts of the body and be fatal. Early treatment is important.

Melanoma
Melanoma

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Causes

Cancer happens when cells divide without control or order. These cells grow together to form a tumor. They can invade and damage nearby tissues. They can also spread to other parts of the body.

It is not clear what causes changes in the cells. It is likely due to genes and environment.

Risk Factors

Melanoma is more common in men and those aged 40 to 60 years old. However, younger people can also get it.

Things that raise the risk are:

  • Moles called dysplastic nevi, or atypical moles
  • Having many moles
  • Having:
    • Light skin and a tendency to have freckles
    • Red or blonde hair
    • Blue or green eyes
  • A family history of melanoma
  • Excessive skin exposure to the sun—without protective clothing or sunscreen
  • Using sun lamps and tanning booths
  • A history of childhood cancer, skin cancer, or skin pre-cancer
  • A weak immune system

Symptoms

Melanomas are not usually painful.

Symptoms may be a change in the size, shape, color, or feel of an existing mole. Melanoma may also appear as a new, dark, discolored, or abnormal mole.

Signs that a mole may be melanoma are (ABCDE rule):

  • A symmetry or uneven shape—one half does not match the shape of the other half
  • B order or edges are uneven
  • C olor varies or is uneven—with shades of black, brown, white, gray, pink, red, or blue
  • D iameter or size—often larger than a pencil eraser (6 millimeters or ¼ inch)
  • E volution or change—often grows larger; changes shape, color, or texture, or may itch

Some melanomas do not fit the ABCDE rule.

Sign of Potential Melanoma
Skin Cancer Sign: Irregular Border on Mole

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Diagnosis

The doctor will ask about symptoms and past health. A physical exam will be done. The doctor will look at the skin and moles. A tissue sample of the area will be taken and tested for cancer.

The doctor may also check lymph nodes. Swollen lymph nodes could mean melanoma has spread. A sample of lymph node tissue may also be removed for testing.

If melanoma is found, more tests will find the stage of cancer. Melanoma is staged from I to IV. Staging shows if the cancer has spread.

Treatment

Treatment will depend on the location and stage of the melanoma. One or more treatments may be used, such as:

  • Surgery to remove the melanoma and some tissue around it
  • Sentinel lymph node biopsy—lymph nodes near the tumor may be removed for testing or to stop the spread of cancer
  • Chemotherapy—drugs to kill cancer cells, if cancer has spread
  • Other medicines such as:
    • Immunotherapy—to help the immune system fight cancer
    • Medicines to target cells with the BRAF gene—a gene that makes melanoma grow fast
  • Radiation therapy—to kill cancer cells and shrink tumors

Prevention

To help lower the risk of melanoma:

RESOURCES:

American Academy of Dermatology
https://www.aad.org

Skin Cancer Foundation
http://www.skincancer.org

CANADIAN RESOURCES:

Canadian Cancer Society
http://www.cancer.ca

Canadian Dermatology Association
https://www.dermatology.ca

REFERENCES:

Kibbi N, Kluger H, et al. Melanoma: clinical presentations. Cancer Treat Res. 2016;167:107-29.

Melanoma treatment—professional version. National Cancer Institute website. Available at: https://www.cancer.gov/types/skin/hp/melanoma-treatment-pdq#section/_1. Accessed September 23, 2021.

Melanoma. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/melanoma. Accessed September 23, 2021.

Melanoma skin cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/melanoma-skin-cancer.html. Accessed September 23, 2021.

Last reviewed July 2021 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP  Last Updated: 9/23/2021