Melanoma is a form of cancer that begins in the bottom of the top layer of skin. Skin cells in this layer called melanocytes produce melanin, a pigment found in the skin, eyes, and hair.
Melanoma of the skin (cutaneous melanoma) usually starts in a mole. Most moles are harmless but if there is a change in the size, shape, color, or feel of a mole, it could be a sign of melanoma or skin cancer.
Melanoma can form anywhere on the skin or in the lymph nodes in the head and neck.