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Diseases and Conditions
Special to CNN.com
Moles, known medically as nevi, are clusters of pigmented cells that often appear as small, dark brown spots on your torso, face, arms and legs. But moles can come in a range of colors and can develop virtually anywhere, including your scalp, armpits, under your nails, and between your fingers and toes.
Most people have between 10 and 40 moles, although the number you have may change throughout life. New moles can appear into mid-adulthood, and because moles last about 50 years, some moles may disappear as you age.
The great majority of moles are harmless, but in rare cases, moles may become cancerous. Monitoring moles and other pigmented patches is an important step in the diagnosis of skin cancer, especially malignant melanoma. Although not all melanomas develop from pre-existing moles, many begin in or near a mole or other dark spot on the skin.
Signs and symptoms
Although the typical mole is a plain, brown spot, moles come in a wide variety of colors, shapes and sizes. They can be flesh-colored, reddish-brown, medium to dark brown, or blue; vary in shape from oval to round, and be as small as a pinhead or large enough to cover an entire limb. Moles that are larger than 8 inches in diameter and present at birth are a special problem. They may need to be removed to avoid the risk of malignant melanoma, the most deadly form of skin cancer.
The surface of a mole can be smooth or wrinkled, flat or raised. Sometimes a mole may start out flat and brown and later become slightly raised and lighter in color. Some may become raised enough that they form a small stalk and are eventually rubbed off. Others may simply disappear.
Although most moles develop by age 20, they can continue to appear until midlife. There are also certain times in your life when moles are more apt to change; for example, they're likely to become darker, larger and more numerous because of hormonal changes during adolescence and pregnancy and with the use of birth control pills.
Melanin is a natural pigment that gives your skin its color. It's produced in cells called melanocytes, either in the top layer of the skin (epidermis) or the outer layers of the skin's second layer (dermis). Melanin is then transported to the surface cells of your skin. Normally, melanin is distributed evenly, but sometimes melanocytes grow together in a cluster, giving rise to moles.
Scientists don't know why moles develop or what purpose they serve, if any, although they do appear to be determined before birth. Most moles are harmless and don't require special care, but some people have unusual-looking moles, called dysplastic nevi, which are more likely to turn cancerous than ordinary moles are. Atypical moles occur most often on the back in both men and women, and also on the abdomen, chest and legs in women.
Several types of moles have a higher than average risk of becoming cancerous. They include:
When to seek medical advice
If a new mole appears past age 20, see your doctor. These signs and symptoms may indicate a medical concern:
If you're concerned about any mole, see your doctor or ask for a referral to a dermatologist.
Screening and diagnosis
You may choose to make a skin examination a regular part of your preventive medical care. Talk to your doctor about a schedule that's appropriate for you. A general guideline is every three years for people ages 20 to 39, and annually for people age 40 or older.
Your doctor will examine your skin from head to toe, including your scalp, your palms, the soles of your feet and the skin between your buttocks. If your doctor suspects that a mole may be cancerous, he or she may take a sample of the tissue (biopsy) and submit the biopsy for microscopic examination.
If your doctor takes a tissue sample of the mole and finds it to be cancerous, the entire mole and a margin of normal tissue around it needs to be removed. Usually a mole that has been removed won't reappear. If it does, see your doctor promptly.
Treatment of most moles usually isn't necessary. For cosmetic reasons, a mole can be removed in several ways:
These procedures are usually performed in the office of your doctor or dermatologist and take only a short time.
The best way to catch potential problems at an early stage is to become familiar with the location and pattern of your moles. Examine your skin carefully on a regular basis — monthly if you have a family history of melanoma, and at least every three months otherwise — to detect early skin changes that may signal melanoma.
Remember to check areas that aren't exposed to sunlight, including your scalp, armpits, feet (the soles and between the toes), genital area and, if you're a woman, the skin underneath your breasts. If necessary, use a hand-held mirror along with a wall mirror to scan hard-to-see places such as your back. People with dysplastic nevi are at greater risk of developing malignant melanoma and may want to consider having a dermatologist check their moles on a regular basis.
To detect melanomas or other skin cancers, use the A-B-C-D skin self-examination guide, adapted from the American Academy of Dermatology:
In addition to periodically checking your moles, you can take protective measures to protect yourself from cancerous changes:
If you have a mole that's unattractive, you may choose to cover it up using makeup designed to conceal blemishes and moles. If you have a hair growing from a mole, it may be possible to clip it close to the skin's surface. Dermatologists also can permanently remove hair from moles. If you have a mole in a beard, you may want to have it removed by your doctor because shaving over it repeatedly may cause irritation. You may also want to have moles removed from other parts of your body that are vulnerable to trauma and friction.
Anytime you cut or irritate a mole, be sure to keep the area clean. See your doctor if the mole doesn't heal.
December 05, 2005