The skin

The body’s largest organ

It protects against heat, light, injury, and infection. It helps control body temperature. It stores water and fat.

The skin has three main layers:

  • Epidermis: The epidermis is the top layer of the skin. It is mostly made of flat cells called squamous cells. Under the squamous cells in the deepest part of the epidermis are round cells called basal cells. Cells called melanocytes make the pigment (color) found in skin and are located in the lower part of the epidermis.
  • Dermis: The dermis is under the epidermis. It contains blood vessels, lymph vessels, and glands. Some of these glands make sweat, which helps cool the body. Other glands make sebum. Sebum is an oily substance that helps keep the skin from drying out. Sweat and sebum reach the surface of the skin through tiny openings called pores.
  • Hypodermis (subcutaneous layer): Below the dermis is the hypodermis. It is composed of adipose tissue.

Understanding Skin Cancer

Skin cancer begins in cells, the building blocks that make up the skin. Normally, skin cells grow and divide to form new cells. Every day skin cells grow old and die, and new cells take their place.

Sometimes, this orderly process goes wrong. New cells form when the skin does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Growths or tumors can be benign or malignant. Benign growths are not cancer and are rarely life-threatening.

  • Generally, benign growths can be removed. They usually do not grow back.
  • Cells from benign growths generally do not invade the tissues around them.
  • Cells from benign growths do not spread to other parts of the body.

Malignant growths are cancer and more serious than benign growths. They may be life-threatening.

  • Malignant growths often can be removed. But sometimes they grow back.
  • Cells from malignant growths can invade and damage nearby tissues and organs.
  • Cells from some malignant growths can spread to other parts of the body. The spread of cancer is called metastasis.

More information on Skin Cancer

Types of Skin Cancer

Skin cancers are named for the type of cells that become cancerous. The two most common types of skin cancer are basal cell cancer and squamous cell cancer. These cancers usually form on the head, face, neck, hands, and arms, i.e. areas are exposed to the sun. But skin cancer can occur anywhere.

Basal cell carcinoma grows slowly. It usually occurs on areas of the skin that have been in the sun. It is most common on the face. Basal cell cancer rarely spreads to other parts of the body. More on Basal Cell Carcinoma

Squamous cell skin cancer also occurs on parts of the skin that have been in the sun. But it also may be in places that are not in the sun. Squamous cell cancer sometimes spreads to lymph nodes and organs inside the body. More on Squamous Cell carcinoma

Melanoma is a disease of the skin in which the cancer (malignant) cells are those that color the skin (melanocytes). Melanoma usually occurs in adults, but it may occasionally be found in children and adolescents. Melanocytes are found in the epidermis and they contain melanin (brown pigment), which gives the skin its color. More on Melanoma

Dysplastic (Atypical) Nevi (Atypical Mole)

It can be difficult to distinguish some benign pigmented lesions or moles (nevi) from melanoma by physical examination. Individuals with many dysplastic nevi have been found to have an increased risk of future melanoma. More on Dysplastic Nevi

Risk Factors for Skin Cancer

Doctors cannot explain why one person develops skin cancer and another does not. However, we do know that skin cancer is not contagious. You cannot “catch” it from another person. Research has shown that people with certain risk factors are more likely than others to develop skin cancer. A risk factor is something that may increase the chance of developing a disease.

Studies have found the following risk factors for skin cancer:

  • Ultraviolet (UV) radiation: UV radiation comes from the sun, sunlamps, tanning beds, or tanning booths. A person’s risk of skin cancer is related to their lifetime exposure to UV radiation. Most skin cancer appears after age 50, but the sun damages the skin from an early age.

UV radiation affects everyone. But people who have fair skin that freckles or burns easily are at greater risk. These people often also have red or blond hair and light-colored eyes. But even people who tan can get skin cancer.

People who live in areas that get high levels of UV radiation have a higher risk of skin cancer. In the United States, areas in the south (such as Texas and Florida) get more UV radiation than areas in the north (such as Minnesota). Also, people who live in the mountains get high levels of UV radiation.

UV radiation is present even in cold weather or on a cloudy day.

  • Scars or burns on the skin
  • Infection with certain human papillomaviruses
  • Chronic skin inflammation or skin ulcers
  • Diseases that make the skin sensitive to the sun, such as xeroderma pigmentosum, albinism, and basal cell nevus syndrome
  • Radiation therapy
  • Medical conditions or drugs that suppress the immune system
  • Personal history of one or more skin cancers
  • Family history of skin cancer

If you think you may be at risk for skin cancer, you should discuss this concern with your doctor. Your doctor may be able to suggest ways to reduce your risk and can plan a schedule for checkups.


The best way to prevent skin cancer is to protect yourself from the sun. Also, protect children from an early age. Doctors suggest that people of all ages limit their time in the sun and avoid other sources of UV radiation. It is best to stay out of the midday sun (from mid-morning to late afternoon) whenever you can. You also should protect yourself from UV radiation reflected by sand, water, snow, and ice.

UV radiation can go through light clothing, windshields, windows, and clouds. Wear long sleeves and long pants of tightly woven fabrics, a hat with a wide brim, and sunglasses that absorb UV. Use sunscreen lotions. Sunscreen may help prevent skin cancer, especially broad-spectrum sunscreen (to filter UVB and UVA rays) with a sun protection factor (SPF) of at least 15. But you still need to avoid the sun and wear clothing to protect your skin. Stay away from sunlamps and tanning booths.

More on skin cancer prevention

More on sunscreen

Proper application of sunscreen

Self-Tanning Products

The popularity of self-tanning products is surging, showing that Americans are wising up about sun safety. They’re putting their money where their skin is.

Self-tanning products, also called “sunless” tanning lotions, contain dihydroxyacetone (DHA), a colorless sugar that interacts with dead surface cells in the epidermis, staining the skin darker. The effect is temporary, because as the dead cells naturally slough off, the color fades, disappearing within a week unless the lotion has been reapplied.

That’s a lot more healthful than a suntan, however, because while suntans also start fading after a few days, the harm done to the skin is permanent. Getting a suntan breaks down the DNA in skin cells, but using self-tanners causes no such damage. At worst, sunless tanning products present a minimal risk of irritant or allergic reactions.

Recent improvements in these sunless products have made the demand skyrocket. “They’re easier to use than ever, the color appears more natural, and some lotions even contain sunscreen with a high sun protection factor (SPF),” says Stanley B. Levy, MD, adjunct clinical professor of dermatology at the University of North Carolina School of Medicine in Chapel Hill.

Recent research shows, furthermore, that while DHA provides only minimal SPF protection against the sun’s shorter-wave UVB rays, higher DHA concentrations that turn the skin darker may provide extra protection against the sun’s longer-wave UVA rays, which, like UVB, are linked to premature skin aging (photoaging) and skin cancer.

But you cannot assume you are adequately UV-protected just because your skin turns darker. At best, the DHA in self-tanning lotions offers protection equivalent to an SPF of only 2 to 4. The Skin Cancer Foundation maintains that SPFs of 15 or higher are required for adequate protection. So even if a product has a high concentration of DHA, it must also contain an SPF 15+ sunscreen if you want to be properly protected. “And remember, even if the lotion contains such a sunscreen, the protection lasts only a couple of hours, not for the duration of the color change,” notes Dr. Levy. “After two hours in the sun at most, you should put on more sunscreen.”

Sunless tanning lotions now come in light, medium, and dark tones. People with dry skin can buy brands with emollients or humectants added for softness and moisture, while people with oily skin may find that gel or alcohol-based products work better. And recently, ingredients such as vitamins, herbal extracts, antioxidants, and alpha-hydroxy acids are being added to some products in an effort to expand their benefits. More on Sunless tanning and application of lotion.

How To Do a Skin Self-Exam

Your doctor or nurse may suggest that you do a regular skin self-exam to check for skin cancer, including melanoma.

The best time to do this exam is after a shower or bath. You should check your skin in a room with plenty of light. Use a full-length mirror and a hand-held mirror. It’s best to begin by learning where your birthmarks, moles, and other marks are and their usual look and feel. By checking your skin regularly, you will learn what is normal for you. It may be helpful to record the dates of your skin exams and to write notes about the way your skin looks. If your doctor has taken photos of your skin, you can compare your skin to the photos to help check for changes. More on Skin Self-exam

  1. Check for anything new:
  • New mole (that looks different from your other moles)
  • New red or darker color flaky patch that may be a little raised
  • New flesh-colored firm bump
  • Change in the size, shape, color, or feel of a mole
  • Sore that does not heal
  1. Check yourself from head to toe. Don’t forget to check your back, scalp, genital area, and between your buttocks.
  2. Look at your face, neck, ears, and scalp. You may want to use a comb or a blow dryer to move your hair so that you can see better. You also may want to have a relative or friend check through your hair since it may be hard to check your scalp by yourself.
  3. Look at the front and back of your body in the mirror. Then, raise your arms and look at your left and right sides. Bend your elbows. Look carefully at your fingernails, palms, forearms (including the undersides), and upper arms.
  4. Examine the back, front, and sides of your legs. Also look around your genital area and between your buttocks. Sit and closely examine your feet, including your toenails, your soles, and the spaces between your toes.

If you find anything unusual, see your doctor.

Symptoms of Skin Cancer

A change on the skin is the most common sign of skin cancer. This may be a new growth, a sore that doesn’t heal, or a change in an old growth. Not all skin cancers look the same.

Skin changes to watch for:

  • Small, smooth, shiny, pale, or waxy lump
  • Firm red lump
  • Sore or lump that bleeds or develops a crust or a scab
  • Flat red spot that is rough, dry, or scaly and may become itchy or tender
  • Red or brown patch that is rough and scaly

Sometimes skin cancer is painful, but usually it is not.

Most basal cell and squamous cell skin cancers can be cured if found and treated early.

Diagnosis of Skin Cancer

If you have a change on the skin, the doctor must find out whether it is due to cancer or to some other cause. Your doctor removes all or part of the area that does not look normal. This is called a biopsy. A biopsy is the only sure way to diagnose skin cancer. You may have the biopsy in a doctor’s office or as an outpatient in a clinic or hospital. Where it is done depends on the size and place of the abnormal area on your skin. You probably will have local anesthesia. The biopsy goes to a lab where a pathologist checks the sample under a microscope.

There are four common types of skin biopsies:

  • Punch biopsy: The doctor uses a sharp, hollow tool to remove a circle of tissue from the abnormal area.
  • Incisional biopsy: The doctor uses a scalpel to remove part of the growth.
  • Excisional biopsy: The doctor uses a scalpel to remove the entire growth and some tissue around it.
  • Shave biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth.

More about skin biopsies


If the biopsy shows that you have cancer, your doctor needs to know the extent (stage) of the disease. In a very few cases, the doctor may check your lymph nodes to stage the cancer.

The stage is based on:

  • The size of the growth
  • How deeply it has grown beneath the top layer of skin
  • Whether it has spread to nearby lymph nodes or to other parts of the body

Treatment for skin cancer depends on the type and stage of the disease, the size and place of the growth, and your general health and medical history. In most cases, the aim of treatment is to remove or destroy the cancer completely.

Additional information related to the skin can be found at:

American Academy of Dermatology

American Osteopathic College of Dermatology

American Society of Dermatopathology