This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science.
This page was updated on June 1, 2022.
The skin is made of a variety of cells, many of which are in constant motion. Round basal cells below the surface flatten as they rise to replace dead, flaking squamous cells on the surface. Melanocytes tan the skin in the sunlight, and Merkel cells give skin its ability to sense touch. When these cells become damaged, they may develop into skin cancer.
All skin cancers are serious and should be treated promptly. But skin cancer types, treatment options and prognoses vary widely depending on the types of cells affected. Common types of skin cancer include:
Of the more than 3 million cases of skin cancer diagnosed every year, more than 80 percent are basal cell carcinoma, according to the American Cancer Society. These cancers develop within the basal cell layer of the skin, the lowest part of the epidermis.
This type of skin cancer tends to occur in areas of the skin that receive the most exposure to the sun, like the head and neck. Basal cell cancers usually grow slowly, and it is rare for them to spread, or metastasize, to nearby lymph nodes or even to more distant parts of the body. But this may occur if it is left untreated, so early detection and treatment are important.
Basal cell cancers may also recur in the same location where the original cancer formed. Patients who have had basal cell carcinoma once have an increased risk of developing a new basal cell cancer elsewhere. As many as 50 percent of these patients may develop a new basal cell carcinoma within five years of their first diagnosis.
Basal cell carcinomas are the most common type of skin cancer, according to the American Cancer Society. These cancers develop within the basal cell layer of the skin, in the lowest part of the epidermis.
Patients who have had basal cell carcinoma once have an increased risk of developing a recurrent basal cell cancer. Basal cell cancers may recur in the same location that the original cancer was found or elsewhere in the body. As many as 50 percent of cancer patients are estimated to experience basal cell carcinoma recurrence within five years of the first diagnosis.
Basal cell carcinomas typically grow slowly, and it is rare for them to metastasize or spread to nearby lymph nodes or other parts of the body. But early detection and treatment are important.
After completing treatment for basal cell carcinoma, it is important to perform regular self-examinations of the skin to look for new symptoms, such as unusual growths or changes in the size, shape or color of an existing spot. Skin cancers typically develop in areas of the body that are exposed to the sun, but they may also develop in areas with no sun exposure. Tell your oncologist or dermatologist about any new symptoms or suspicious changes you may have noticed.
Patients who have been diagnosed with basal cell carcinoma should be watchful for signs of recurrence, because they are at a higher risk for developing additional skin cancers. It is difficult to determine a patient’s basal cell carcinoma recurrence risk, but recurrence is more likely in patients who:
Continued follow-up care is necessary for many years after treatment for basal cell carcinoma. Once your initial cancer treatment is completed, follow-up appointments and self-examinations are strongly recommended to help detect and diagnose skin irregularities.
These cancers are the second most common type of skin cancer, accounting for approximately 20 percent of non-melanoma skin cancers. They develop from the flat squamous cells that make up much of epidermis, the outermost layer of the skin.
This type of skin cancer is usually found on areas of the skin that have been exposed to the sun, such as the neck, ears, face or the back of the hand, but they may develop in other areas, such as in scars, skin ulcers or the genital region. Squamous cell cancers usually grow slowly, and it is uncommon for them to spread, or metastasize. But they are more likely than basal cell carcinomas to invade fatty tissue beneath the skin or to spread even further.
Melanoma is a cancer that forms in melanocytes, or the skin cells that produce the brown pigment known as melanin. These are the cells that darken when exposed to the sun, a protective response to shield the deeper layers of the skin from the harmful effects of UV rays.
This rare but aggressive form of skin cancer begins in Merkel cells that, along with nerve endings, give the skin its sense of touch. Merkel cell carcinomas may be more common in areas of the skin exposed to the sun, such as the face or scalp. People older than 50 with a compromised immune system are at higher risk of developing this type of skin cancer. Merkel cell carcinomas may metastasize to the brain, bones, liver or lungs.
Other skin cancer types are very rare, including these:
Kaposi sarcoma (KS) is caused by human herpesvirus 8, also known as Kaposi sarcoma associated herpes virus. This cancer usually appears as lesions or tumors on the skin. Tumors may also form in the mouth, lungs or digestive tract. Most U.S. cases of KS involve patients infected with HIV, the virus that causes AIDS. But KS may occur in other patients whose immune system is severely compromised.
Actinic keratosis is a pre-cancerous growth that may develop into squamous cell carcinomas if left untreated. These growths may be found in clusters on skin damaged by exposure to ultraviolet (UV) radiation.
Lymphoma of the skin, or cutaneous lymphoma, is a type of non-Hodgkin lymphoma. Most cases of lymphoma form in the lymph nodes, which are small glands scattered throughout the body that produce disease-fighting T-cells and B-cells, also known as lymphocytes. But lymphomas may also develop in other lymphoid tissue, including the spleen, bone marrow and skin. This rare cancer may appear as a rash or bumps on the skin.
Keratoacanthoma are typically benign (non-cancerous) tumors that grow slowly and often go away on their own. Keratoacanthoma tumors that do continue to grow are often treated like a form of squamous cell carcinoma.
Next topic: What are the stages of skin cancer?