There are many forms of skin cancer, with the two most common being basal cell carcinoma and squamous cell carcinoma.  One of the most dangerous types of skin cancer, however, is melanoma, which may begin as a mole that alters in appearance or could originate on normal skin.  More than 90 percent of melanomas are caused by mutations in the DNA of skin cells called melanocytes (which produce the pigment melanin).  Melanomas originating on the skin are called cutaneous melanomas.  Less commonly, melanoma can also appear in other locations, such as the eyes or sinuses.

Melanoma Skin Cancer

Source: Mount Sinai