Malignant melanoma

Last revised by Daniel MacManus on 16 Jul 2023

Malignant melanoma is a malignant neoplasm that arises from melanocytes (or cells that derive from melanocytes).  

Melanocytes predominantly occur in the basal layer of the epidermis and most melanomas, therefore, arise in the skin.  However, melanocytes do occur in other locations and can give rise to primary melanoma in unexpected locations, e.g. primary uveal malignant melanoma.

Thus, melanoma may be primary or metastatic and the primary form may arise from the skin or (much more infrequently) from other sites. Each is discussed separately:

In general, radiology is useful for identifying metastatic melanomatous deposits.

Despite being one of the less common types of skin cancer, they cause the majority (75%) of skin cancer-related deaths.

Prognosis is related to stage of disease. Staging for malignant melanoma is accomplished using the American Joint Committee on Cancer (AJCC), 8th edition melanoma staging system which has been in use since January 1, 2018 5.

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