Actinic keratosis (AK) The most common type of precancerous skin lesion. It looks like crusty or scaly skin patches and appears on areas that are frequently exposed to the sun or artificial light. Asymmetry When a mole or lesion has two sides or halves that aren’t the same. Basal cell carcinoma A type of skin cancer, basal cell carcinoma is highly curable and accounts for about 80 percent of all cases. Basal cell nevus syndrome A rare genetic disorder that causes a person to develop numerous basal cell cancers, sometimes in childhood or adolescence. Biopsy A procedure that’s done to study a suspicious lesion. A doctor removes a small sample of the lesion and has it examined in the lab to determine if it’s cancerous. Cryosurgery A treatment that involves applying liquid nitrogen to a growth with a swab or spray. Cryosurgery is sometimes used to treat small basal cell and squamous cell carcinomas, as well as some precancers. Curettage and electrodesiccation An approach that combines curettage (scraping) and desiccation (burning) to remove small and uncomplicated basal cell or squamous cell cancers. It’s usually performed as an outpatient procedure in a doctor’s office. Cutaneous (skin) lymphoma A rarer type of cancer that starts in the white blood cells, called lymphocytes, in the skin. Dermis The layer of skin that lies beneath the epidermis. Epidermis The outer layer of the skin. Excisional surgery A procedure to remove many types of skin cancer. Doctors use a scalpel to cut out the entire tumor and a surrounding border of healthy skin as a safety margin. Immunotherapy A treatment that harnesses the body’s immune system to fight cancer. It has helped improve survival rates for people with advanced melanoma. Invasive skin cancer Skin cancer that’s penetrated beyond the epidermis and into the dermis and grows into surrounding tissue. Kaposi sarcoma Cancer of the cells that line lymph or blood vessels. Kaposi sarcoma appears as lesions on the skin, mouth, or other places in the body. The most common type develops in people who have the HIV virus. Lymph nodes Small glands in your body that are part of your immune system. Melanocyte Skin cells that produce a skin-darkening pigment called melanin. Exposure to UV light damages melanocytes, which can lead to melanoma. Melanoma A form of skin cancer that develops in the melanocytes. It’s rare and accounts for about 1 percent of all skin cancer cases. Melanoma is curable if it’s caught early but can be fatal if it spreads throughout the body. Merkel cell carcinoma A rare type of skin cancer that develops in cells found at the base of the epidermis, close to nerve endings. Merkel cell usually appears as a flesh-colored or bluish-red nodule and is very aggressive. Metastasis When cancer cells spread from the primary tumor to new areas of the body. Mohs surgery A surgical technique used to treat skin cancer. With Mohs surgery, a specially trained doctor removes thin layers of skin containing a tumor and examines it under a microscope. This is repeated until only noncancerous tissue remains. Mole A pigmented spot on the body that occurs when cells in the skin grow in a cluster. Photodynamic therapy (PDT) A treatment that involves using a special light source to destroy cancer cells. Radiation A type of therapy that delivers beams of intense energy to kill cancer cells. It’s sometimes used for basal or squamous cell carcinomas that are difficult to remove surgically. Or, a doctor might recommend radiation for a person who is elderly or in poor health. Skin adnexal tumors Cancers that start in the hair follicles or skin glands. Squamous cell carcinoma A type of skin cancer that accounts for about 20 percent of all cases and is highly treatable. But it’s more likely to spread than basal cell carcinoma. Targeted therapy A treatment that focuses on attacking certain traits of skin cancer cells, such as gene changes. Ultraviolet (UV) rays Rays that are found in sunlight and can damage the skin. There are two basic types: UVA and UVB. UVA rays UV rays that penetrate deep in the skin and can cause premature aging and some skin cancers. UVA is the main type of light used in tanning beds. UVB rays UV rays that damage the outermost layers of the skin. They’re most responsible for producing a sunburn and play a role in the development of skin cancer. Xeroderma pigmentosum An uncommon inherited condition that makes a person’s skin unable to repair DNA damage from UV exposure.
