The most common types of skin cancer include basal cell carcinoma, squamous cell carcinoma and melanoma, according to WebMD. Rare types of skin cancer include Merkel cell tumors and dermatofibrosarcoma protruberans.
Basal cell carcinoma and squamous cell carcinoma are typically grouped together and called non-melanoma skin cancers, WebMD explains. Melanoma is the highly aggressive skin cancer that can be fatal if it is not detected and treated early; however, melanoma comprises a small fraction of skin cancer cases. Most skin cancers are basal cell carcinomas and squamous cell carcinomas. These non-melanoma cancers usually do not spread to different parts of the body, so they are rarely deadly. They can cause disfigurement if not diagnosed and treated early.
Most skin cancer develops from a pre-cancerous lesion, WebMD reports. The lesions are changes in skin that may, but not always, become cancerous. They include rough, scaly skin that appears red or brown, which can become squamous cell carcinoma, and abnormal moles.
As of 2015, skin cancer cases are up considerably in the United States, WebMD says, but patients are reporting better outcomes because of earlier detection and treatment. Ultraviolet rays from the sun are by far the biggest cause of skin cancer. People with fair skin that freckles are the most at risk.