The largest organ of the body, the skin serves many important functions in protecting other organs from the external environment. It helps the body retain water and other necessary fluids while also helping to regulate its temperature and protect it from infections. The skin has three layers: the epidermis, the dermis and the subcutaneous layer. Melanocytes, located in the bottom layer of the epidermis, make a pigment called melanin, which gives the skin a tan or brown color and helps protect the deeper layers of the skin from the harmful effects of the sun. Melanoma is a type of skin cancer that begins in the melanocytes.
Because most melanoma cells keep making melanin, melanoma tumors are often brown or black. Melanoma most often appears on the trunk of fair-skinned men and on the lower legs of fair-skinned women, but it can appear other places as well. Melanoma is almost always curable in its early stages.
Incidence
Cancer of the skin is the most common of all cancers. Melanoma accounts for only about 1 percent of skin cancer cases but causes a large majority of skin cancer deaths. The American Cancer Society estimates that 87,110 new cases of melanoma (about 52,170 in men and 34,940 in women) will be diagnosed in the United States in 2017, and that about 9,730 people will die from the disease. The rates of melanoma have been rising for the last 30 years.