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Basal Cell Carcinoma


Vinod E. Nambudiri

, MD, MBA, EdM, Harvard Medical School

Reviewed/Revised Jan 2024
Topic Resources

Basal cell carcinoma, the most common skin cancer, originates in certain cells of the outer layer of the skin (epidermis).

  • Usually, a small, shiny bump appears on the skin and enlarges slowly.

  • The bumps may break open and form a scab, sometimes with bleeding, or become flat, resembling a scar.

  • This cancer can often be identified by sight, but doctors usually do a biopsy.

  • The cancer is usually removed, but sometimes people may be given chemotherapy drugs applied to the skin, immunotherapy, or, occasionally, radiation therapy or medications taken by mouth.

Basal cells are in the lowest layer of the epidermis (the outer layer of the skin). Although basal cell carcinoma may not develop from the basal cells, the disease is so named because the cancer cells look like basal cells under a microscope.

Basal cell carcinoma is most common among people who have light skin and a history of sun exposure. It is very rare among people with dark skin.

Basal cell carcinoma usually develops on skin surfaces that are exposed to sunlight, commonly on the head or neck, and may develop in a type of birthmark that often appears on the scalp (nevus sebaceus). Basal cell carcinoma also may develop in people who have certain hereditary disorders, such as xeroderma pigmentosum, Gorlin syndrome, and Bazex syndrome.

The tumors enlarge very slowly, sometimes so slowly that they go unnoticed as new growths. However, the growth rate varies greatly from tumor to tumor, with some growing as much as ½ inch (about 1 centimeter) in a year.

Basal cell carcinomas rarely spread (metastasize) to other parts of the body. Instead, they invade and slowly destroy surrounding tissues. When basal cell carcinomas grow near the eyes, ears, mouth, bone, or brain, the consequences of spread can be serious and can lead to death. Yet, for most people, the tumors simply grow slowly into the skin.

Symptoms of Basal Cell Carcinoma

There are several types of basal cell carcinomas.

The nodular type of basal cell carcinoma usually begins as small, shiny, firm, almost clear to pink in color, raised growth. After a few months or years, visible dilated blood vessels (telangiectases) may appear on the surface, and the center may break open and form a scab. The border of the cancer is sometimes thickened and pearly white. The cancer may alternately bleed and form a scab and heal, leading a person to falsely think that it is a sore rather than a cancer.

Other types of basal cell carcinomas vary greatly in appearance. For example, the superficial type appears as flat, thin, red or pink patches, and the morpheaform type appears as thicker flesh-colored or light red patches that look somewhat like scars.

Examples of Basal Cell Carcinoma

Diagnosis of Basal Cell Carcinoma

  • Biopsy

Doctors often can recognize a basal cell carcinoma simply by looking at it, but a biopsy Biopsy Doctors can identify many skin disorders simply by looking at the skin. A full skin examination includes examination of the scalp, nails, and mucous membranes. Sometimes the doctor uses a hand-held... read more Biopsy is the standard procedure for confirming the diagnosis. During this procedure, doctors remove a piece of the tumor and examine it under a microscope.

Treatment of Basal Cell Carcinoma

  • Removal of the tumor (many different methods)

Basal cell carcinomas should be treated by a specialist.

Doctors may remove the cancer in the office by scraping and burning it with an electric needle (a procedure called curettage and electrodesiccation) or by cutting it out. Doctors may destroy the cancer by using extreme cold (cryosurgery).

A technique called Mohs microscopically controlled surgery Mohs Microscopically Controlled Surgery Mohs Microscopically Controlled Surgery may be required for some basal cell carcinomas that are large or regrow or occur in certain areas, such as around the nose and eyes.

People whose cancer has spread to nearby tissues or spread to other parts of the body (metastasized) and who are not candidates for surgery or radiation therapy may be given the medication vismodegib or sonidegib by mouth. People who cannot take vismodegib or sonidegib may be given a type of immunotherapy Monoclonal antibodies Immunotherapy is used to stimulate the body's immune system against cancer. These treatments target specific genetic characteristics of the tumor cells. The genetic characteristics of tumors... read more called cemiplimab.

Mohs Microscopically Controlled Surgery

Because skin cancer cells often have spread beyond the edges of the visible patch on the skin, dermatologists sometimes use a special surgical technique to make sure they remove all of the cancer. In this technique, called Mohs microscopically controlled surgery or Mohs micrographic surgery, dermatologists first remove the visible tumor and then begin cutting away the edges of the wound bit by bit. During surgery, the dermatologist examine pieces of tissue to look for cancer cells. Tissue removal from the area continues until the samples no longer contain cancer cells. This procedure enables dermatologists to limit the amount of tissue removed and thus is especially useful for removing cancers near such delicate sites as the eye.

After removing all of the cancer, dermatologists decide how best to replace the skin that has been cut away. They may bring the edges of the remaining skin together with sutures or use a skin graft Skin Tissue transplantation is the removal of various tissues, such as skin cells, corneas, cartilage, or bone, from a body and then inserting that tissue into the same or another person who has... read more or skin flap. Or they may place a dressing on top of the wound and let the skin heal on its own.

Mohs surgery reduces recurrence rates for skin cancers. This surgery is useful for basal cell and squamous cell cancers but is less often used for melanoma.

Prognosis for Basal Cell Carcinoma

Treatment of basal cell carcinoma is nearly always successful, and the cancer is rarely fatal. However, almost 25% of people who have had 1 basal cell carcinoma develop a new basal cell cancer within 5 years of the first one. Thus, anyone with one basal cell carcinoma should have a yearly skin examination.

Prevention of Basal Cell Carcinoma

Because basal cell carcinoma is often caused by sun exposure, people can help prevent this cancer by doing the following, starting in early childhood:

In addition, any skin change that lasts for more than a few weeks should be evaluated by a doctor.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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