Melanoma, the most serious type of cancer, develops in the cells (melanocytes) that produce melanin – the pigment that gives skin color. It can also form in the eyes and more rarely in organs such as the intestines. It generally begins on the surface of the skin and resembles a mole. As it grows, it takes on changing traits such as color, asymmetrical shape, oozing or bleeding, increased diameter and itching. While the exact cause is not clear, exposure to ultraviolet (UV) radiation from sunlight or tanning lamps dramatically increases the risk of developing melanoma. Treatment for melanoma may include surgical removal of the cancerous regions and lymph nodes, chemotherapy, and radiation therapy.