Squamous cell carcinoma (SCC) is the second most common type of skin cancer. Much like BCC, it originates in the epidermis (the outermost layer of the skin) and typically occurs in sun exposed skin, but may occur anywhere on the body.

SCC causes a local destruction and is usually slow growing. SCC rarely spreads internally. Although squamous cell carcinomas usually remain confined to the skin for some time, they may eventually penetrate the underlying tissues if not treated. In a small percentage of cases, they metastasize (spread) to local lymph nodes, distant lymph nodes or organs. Anyone with a history of frequent sun exposure can develop SCC, but people who have fair skin, light hair or light eyes are at highest risk. Those whose occupations require long hours in the outdoors or who spend extensive leisure time in the sun are at greatest risk for development of SCC.

Chronic exposure to ultraviolet radiation (sunlight) is the most common cause of squamous cell carcinoma, and tumors most frequently appear on the sun-exposed parts of the body: the face, neck, scalp, hands, shoulders, arms and back. The rim of the year and the lower lip are especially vulnerable to the development of these cancers. Development of squamous cell carcinoma may be increased by certain medical conditions, such as infection of the Human Immunodeficiency Virus (HIV) or by medicines that suppress the immune system such as medications for organ transplant recipients.