Basal cell carcinoma and squamous carcinoma are the two main forms of non-melanoma skin cancer. Together, they account for about 95 percent of all non-melanoma skin cancers, according to the American Cancer Society.

Other forms are much rarer and they include Kaposi’s sarcoma, which begins in the blood vessels of the skin and produces red or purple patches in the skin or mucous membranes. As with melanoma, Kaposi’s sarcoma can be a deadly form of skin cancer. It is most often seen in those individuals who already have a compromised immune system, such as those infected with HIV or those who have full-blown AIDS. It also occurs with individuals who have undergone an organ transplant and are taking immunosuppressive medications.

Cutaneous lymphoma, skin adnexal tumors, Merkel cell carcinoma and various types of sarcomas are other less common forms of non-melanoma skin cancer. Additionally, actinic keratoses, also known as solar keratoses, can develop into non-melanoma skin cancer in a small number of affected people.

This skin condition is characterized by rough, scaly patches that range in color from brown to dark pink. These patches are often found on fair-skinned people who have skin damage from overexposure to the sun’s ultraviolet (UV) rays, especially on the face, ears, lower arms and hands.