Skin cancer is a disease in which malignant cells are found in one of the layers of the skin. Skin, the body's largest organ, protects the body against heat, light, infection and injury. The dermis contains blood vessels, hair follicles, sweat glands, and oil glands. The epidermis consists of mostly flat, scale-like cells known as squamous cells. Beneath the squamous cells are round basal cells.
Melanocytes are in the epidermis.
They contain malanin, the pigment of the skin. Benign tumors are not cancerous. In the skin, examples of benign tumors are moles and non-cancerous warts. Most people have between 10 to 40 moles. Malignant tumors are cancerous.