Melanoma is the most dangerous skin cancer and when advanced can cause extreme illness and even death. However, if caught early, it is almost always curable. Early staged melanoma is often referred to as "melanoma in situ" or "lentigo maligna".
Melanoma begins in melanocytes, the cells throughout the skin that produce the pigment called melanin which makes the skin tan. Melanoma may appear suddenly or begin in or near an existing mole. Though melanoma may occur anywhere on your skin, melanoma is found most often on the legs of women or the backs of men.
The two largest risk factors are sun exposure and heredity, but fortunately, it rarely occurs without warning. It is usually a brown to black lesion which is not uniform in border, color or surface. The "ABCDE's of melanoma" have been described to help distinguish a regular mole from melanoma. The acronym stands for Asymmetry (most healthy moles are uniform), Border (irregular), Color (irregular or change in), Diameter (larger than a pencil eraser-not reliable), and Evolving (changing). Melanomas on chronically sun-damaged skin like the face may appear like a brown patch or freckle with irregular color.
Image used with permission of the American Academy of Dermatology National Library of Dermatologic teaching slides. ©2005 America Academy of Dermatology