Squamous cell carcinoma on the leg of a 78 year old female patient. Squamous cell carcinoma (SCC), also called Bowen's disease, is a very early and slow-growing form of skin cancer that affects the outermost layer of cells (epidermis) in the skin. It typically appears as scaly patches or lesions on the skin, similar to raised spots or warts. SCC usually affects older adults. The cause of the disease often remains unclear, but there are links to long-term sun exposure, immunocompromised people, the human papillomavirus (HPV), and long-term exposure to arsenic. There are many effective treatments for SCC including chemotherapy and immunotherapy creams, cryotherapy (freezing), surgery, laser treatment and radiotherapy. If left untreated, there is a small chance that the disease can spread into the deeper layers of the skin, although the risk of developing skin cancer is less than 10 percent.