Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.

The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The skin has several layers, but the two main layers are the epidermis (upper or outer layer) and the dermis (lower or inner layer). Skin cancer begins in the epidermis, which is made up of three kinds of cells:

  • Squamous cells: Thin, flat cells that form the top layer of the epidermis.
  • Basal cells: Round cells under the squamous cells.
  • Melanocytes: Found in the lower part of the epidermis, these cells make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment, causing the skin to darken.

Skin cancer can occur anywhere on the body, but it is most common in skin that is often exposed to sunlight, such as the face, neck, hands, and arms. There are several types of cancer that start in the skin. The most common types are basal cell carcinoma and squamous cell carcinoma, which are nonmelanoma skin cancers. Actinic keratosis is a skin condition that sometimes develops into squamous cell carcinoma.

Click HERE to see an animation about the different types of Skin Cancer.

Basal cell carcinoma

Basal cell carcinoma is a cancer that begins in the lower part of the epidermis or the outer layer of the skin. It may appear as a small white or flesh-colored bump that grows slowly and may bleed. Basal cell carcinomas are usually found on areas of the body exposed to the sun. Basal cell carcinomas rarely metastasize or spread to other parts of the body. They are the most common form of skin cancer. This may also be called basal cell cancer.

Squamous cell carcinoma

Squamous cell carcinoma is a cancer that begins in squamous cells, which are thin, flat cells that look like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. This is also called epidermoid carcinoma.

Nonmelanoma skin cancer

Nonmelanoma skin cancer forms in the lower part of the epidermis or in squamous cells, but not in melanocytes, skin cells that make pigment.

Actinic keratosis

Actinic keratosis is a thick, scaly patch of skin that may become cancer. It usually forms on areas exposed to the sun, such as the face, scalp, back of the hands, or chest. It is most common in people with fair skin. This is also called Senile Keratosis and Solar Keratosis.


Melanoma is a form of cancer that begins in melanocytes, cells that make the pigment melanin. It may begin in a mole, but can also begin in other pigmented tissues, such as in the eye or in the intestines.

Click HERE to see an informative animation about Melanoma.

Click HERE to see an animation about Melanoma Surgery and Treatment.