Basal Cell Carcinoma Health Article

Definition

A basal 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."

Description

Basal keratinocytes are unpigmented skin cells found deep in the epidermis, hair follicles, and sweat glands. When they become cancerous, these cells invade the dermis (the layer of skin just below the epidermis) and spread out into the normal skin. They become visible as a small growth or area of change in the skin's appearance. These tumors can appear anywhere on the body, but most become evident on the face and neck.

Most basal cell carcinomas are small tumors that can be cured with simple surgeries. They usually grow quite slowly. However, neglected or aggressive tumors can invade vast amounts of skin. These cancers can also spread along bones, cartilage, muscles, and, more rarely, nerves. Some tumors may eventually reach the eye or brain or become large enough to significantly disfigure the face. These serious consequences are more likely if the tumor lies close to bone and cartilage—for instance, at the corner of the eye. Very few basal cell carcinomas spread to more distant organs; no more than five out of every 10, 000 of these tumors metastasize. Most that do are very large, deep cancers that have been visible for years.

Demographics

Basal cell carcinomas are most common from middle age until old age. They are more frequent in men than women. These cancers seem to be associated with exposure to ultraviolet light; they tend to develop on sun-exposed areas and are more common in people living near the equator. Those who have lighter skin are more susceptible; fair-haired blonds are more likely to develop tumors than people with darker complexions. In the United States, Caucasians have a 28% to 33% chance of developing a basal cell carcinoma over a lifetime.

Weakened immunity may also play a role. Those who have had an organ transplanted or who have contracted acquired immune deficiency syndrome (AIDS) are more likely to develop one of these cancers.

Basal cell carcinomas are particularly common among individuals with a rare genetic disease called nevoid basal cell carcinoma syndrome (Gorlin's syndrome). Individuals with this disease can be born with basal cell carcinomas or begin to develop them in childhood. Some have few or no cancers; others have more than 250. These tumors seldom grow much before puberty, but during and after adolescence they can spread rapidly. Other symptoms include small pits in the palms and soles, cysts in the jaw, and other abnormalities in the bones.

Causes and symptoms

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.

Several types of basal cell carcinomas exist. Nodular basal cell carcinomas are the most common form. These tumors begin as a tiny red or clear bump on the skin. Over time, they develop into a growth with clear or white "pearly" raised edges and, often, a depressed area in the middle. A network of tiny blood vessels usually crisscrosses the surface, and the tumor may bleed repeatedly or crust over. Morpheaform (sclerosing, morpheic) basal cell carcinomas are more difficult to detect. These tumors are usually pale, firm, flat growths that can blend into the normal skin around them. Many look just like a scar. Superficial basal cell carcinomas are flat, red, scaly plaques that can look like psoriasis or eczema. Unlike other basal cell carcinomas, they are usually found on the arms, legs, and torso. Pigmented basal cell carcinomas are brown, black, or blue; they are usually of the nodular type and can look like a melanoma.

Some general characteristics of skin cancers include:

• irregular or ragged borders
• non-symmetrical shape
• a change in color
• a size greater than 0.2 inches (6 mm)

Diagnosis

Basal cell carcinomas are usually diagnosed with a skin biopsy taken in the doctor's office. This is generally a brief and simple procedure. After numbing the skin with an injection of local anesthetic, the doctor snips out a tiny piece of the tumor. The skin sample must be sent to a trained pathologist to be analyzed. It may take up to a week for the biopsy results to come back. Sometimes the tumor is removed immediately after the biopsy, before the results are known.

Treatment team

Primary care physicians remove some basal cell carcinomas; other cancers, including larger or more complicated tumors, may be referred to a dermatologist. The services of a plastic surgeon are occasionally necessary. In the rare event that a tumor metastasizes, an oncologist and full cancer treatment team become involved.