Skin Cancer
About Skin Cancer
Nonmelanoma
Skin cancer begins in the epidermis, which is made up of three kinds of cells:
- Squamous cells: Thin, flat cells that form the top layer of the epidermis
- Basal cells: Round cells under the squamous cells
- Melanocytes: Cells that make melanin and are found in the lower part of the epidermis. Melanin is the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment and cause the skin to darken
There are different types of cancer that start in the skin. The most common types are basal cell carcinoma and squamous cell carcinoma, which are nonmelanoma skin cancers. Nonmelanoma skin cancers rarely spread to other parts of the body. Melanoma is a much rarer type of skin cancer. It is more likely to invade nearby tissues and spread to other parts of the body. Actinic keratosis is a skin condition that sometimes becomes squamous cell carcinoma.
Melanoma
Melanoma is a rare form of skin cancer. It is more likely to invade nearby tissues and spread to other parts of the body than other types of skin cancer. When melanoma starts in the skin, it is called cutaneous melanoma. Melanoma may also occur in mucous membranes (thin, moist layers of tissue that cover surfaces such as the lips). This PDQ summary is about cutaneous (skin) melanoma and melanoma that affects the mucous membranes.
In men, melanoma is often found on the trunk (the area from the shoulders to the hips) or the head and neck. In women, melanoma forms most often on the arms and legs. When melanoma occurs in the eye, it is called intraocular or ocular melanoma.
Symptoms
Nonmelanoma
- Areas of the skin that are:
- Raised, and red or reddish-brown
- Raised, smooth, shiny, and look pearly
- Firm and look like a scar, and may be white, yellow, or waxy
- Scaly, bleeding or crusty
- A sore that does not heal
Melanoma
- A change in pigmented (colored) skin
- A mole that:
- Changes in size, shape, or color
- Has irregular edges or borders
- Is more than one color
- Is asymmetrical (if the mole is divided in half, the 2 halves are different in size or shape)
- Itches
- Oozes, bleeds or is ulcerated (a hole forms in the skin when the top layer of cells breaks down and the tissue below shows through)
- Satellite moles (new moles that grow near an existing mole)
Risk Factors
Nonmelanoma
- Being exposed to arsenic
- Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time
- Having a fair complexion, which includes blue or green or other light-colored eyes; fair skin that freckles and burns easily, does not tan, or tans poorly; red or blond hair
- Having a weakened immune system
- Having actinic keratosis
- Having certain changes in the genes that are linked to skin cancer
- Past treatment with radiation
Melanoma
- Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time
- Being exposed to radiation, solvents, vinyl chloride and PCBs
- Being white
- Having a fair complexion, which includes blue or green or other light-colored eyes; fair skin that freckles and burns easily, does not tan, or tans poorly; red or blond hair
- Having a family history of unusual moles (atypical nevus syndrome)
- Having a family or personal history of melanoma
- Having a history of many blistering sunburns, especially as a child or teenager
- Having a weakened immune system
- Having certain changes in the genes that are linked to melanoma
- Having several large or many small moles