The cancer known as melanoma begins in melanocytes, the skin cells that produce the dark protective pigment called melanin. When you’re exposed to sunlight, the melanin in your skin increases to form a protective layer in the form of a suntan. Melanoma consists of melanocytes which have been transformed into cancer cells that grow uncontrollably. Melanoma cells usually still produce melanin, which is why these cancers tend to be mixed shades of tan, brown, and black.
Unlike basal cell and squamous cell carcinomas of the skin, melanoma has a strong tendency to spread to other parts of the body. Once colonies of melanoma cells reach vital internal organs and grow, they are much more difficult to treat. That is why this is a potentially lethal form of cancer.
While melanoma may suddenly appear without warning, it may also begin in or near a mole or other dark spot in the skin. That is why it’s important to know the size and location of the moles on your body, so you’ll recognize any changes that might take place.