NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,804 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

melanoma
(MEH-luh-NOH-muh)
A form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines.

EnlargeAnatomy of the skin with melanocytes; drawing shows normal skin anatomy, including the epidermis, dermis, hair follicles, sweat glands, hair shafts, veins, arteries, fatty tissue, nerves, lymph vessels, oil glands, and subcutaneous tissue. The pullout shows a close-up of the squamous cell and basal cell layers of the epidermis above the dermis with blood vessels. Melanin is shown in the cells. A melanocyte is shown in the layer of basal cells at the deepest part of the epidermis.

Anatomy of the skin, showing the epidermis, dermis, and subcutaneous tissue. Melanocytes are in the layer of basal cells at the deepest part of the epidermis.