Most skin cancers are locally destructive cancerous (malignant) growth of the skin. They originate from the cells of the epidermis, the superficial layer of the skin. Unlike cutaneous malignant melanoma, the vast majority of these sorts of skin cancers rarely spread to other parts of the body (metastasize) and become life-threatening.

There are three major types of skin cancer: (1) basal cell carcinoma (the most common), (2) squamous cell carcinoma (the second most common), which originate from skin cells, and (3) melanoma, which originates from the pigment-producing skin cells (melanocytes) but is less common, though more dangerous, than the first two varieties. Other rare forms of skin cancer include lymphomas, Merkel cell cancers, and cancers of other tissue in the skin, including sarcomas as well as hair and sweat gland tumors. In this article, we will only be reviewing the most common forms of cancers, basal cell carcinoma and squamous cell carcinoma.