The epidermis, or skin, consists of several layers. The outer layer is made up of scale like cells called the squamous epithelium. This layer of tissue covers the surface of much of the body, and lines the cavities of the body. A squamous cell carcinoma is a type of cancer that originates in the squamous epithelium. It may appear to be a white skin mass, or a raised bump on the skin. Often the raised mass will necrotize in the center and ulcerate, with occasional bleeding.