Nonmelanoma Skin Cancer : About

Three Types

  • Basel cell carcinoma is a skin cancer that originates from basal keratinocytes in the top layer of the skin, the epidermis. Sometimes these tumors are called "rodent ulcers."
  • Squamous cell skin cancer is a type of tumor that affects the middle layer of the skin.
  • Melanoma is the most dangerous type of skin cancer. It involves the cells that produce the skin pigment melanin. Melanin is responsible for skin and hair color.
  • Melanoma can also involve the colored part of the eye.


Basal cell carcinomas are caused by genetic damage to a skin cell. Exposure to ultraviolet light and x-rays, suppression of the immune system and genetic factors seem to increase the risk that this will happen. The exact cause, however, is rarely known. The main symptom of squamous cell skin cancer is a growing bump that may have a rough, scaly surface and flat reddish patches. The bump is usually located on the face, ears, neck, hands, or arms, but may occur on other areas. A sore that does not heal can be a sign of squamous cell cancer. Any change in an existing wart, mole, or other skin lesion could be a sign of skin cancer. The primary symptom of any skin cancer is usually a mole, sore, lump, or growth on the skin. Any change in appearance of a pigmented skin lesion over time is a warning sign. Also, watch for any bleeding from a skin growth. The ABCD system may help you remember features that might be a symptom of melanoma:
  • Asymmetry: One half of the abnormal area is different from the other half.
  • Borders: The lesion or growth has irregular edges.
  • Color: Color changes from one area to another, with shades of tan, brown, or black (sometimes white, red, or blue). A mixture of colors may appear within one lesion.
  • Diameter: The trouble spot is usually (but not always) larger than 6 mm in diameter -- about the size of a pencil eraser.