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.
Skin cancer types are categorized by the type of cells involved and where the cancer develops. While some types of skin cancer are common, others are rare.
The skin is made up 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. Early detection may lead to better skin cancer treatment outcomes.
Of the more than 3 million people who get a skin cancer diagnosis every year in the U.S., approximately 80 percent are diagnosed with 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's left untreated, so early skin cancer 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.
Squamous cell carcinomas are the second most common type of skin cancer, accounting for approximately 1.8 million diagnoses each year in the U.S. 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 also develop in other areas, such as in scars, skin ulcers or the genital region. Squamous cell cancers usually grow slowly, and rarely 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 the third most common type of skin cancer and the most lethal. It 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 ultraviolet (UV) rays.
Other skin cancer types are very rare, including those listed below.
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.
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 systems are 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.
This rare type of cancer forms in the sebaceous glands, which are found on the skin and secrete an oily substance to provide lubrication. Sebaceous gland carcinoma is most often found on the eyelids, but can be found anywhere with sebaceous glands.
Dermatofibrosarcoma protuberans is a rare skin cancer type that develops in the dermis, which is the middle layer of skin.
Keratoacanthomas 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. It’s a slow-growing, rare cancer type that may cause a small bump on the skin that looks like a pimple or birthmark.
Also known as squamous cell carcinoma in situ, Bowen disease causes scaly, red patches on the skin, and although it’s typically benign, it’s considered a pre-cancerous condition that should be addressed. This condition is rare and most often affects areas of skin that have gotten sun exposure.
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