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Moles or nevi are small growths of pigment-producing cells in the skin. All people have some moles on their skin, though some people are prone to develop more moles than others due to differences in skin type. The vast majority of nevi are perfectly harmless, but moles that show changes in colors or irregular shapes might indicate more serious problems.

In general, we are born without any moles. Birthmark moles do occur in 1% of newborn babies, but if they are small in size then there is very little risk that these moles would ever become cancerous. Most children then start to acquire a few small flat brown moles from toddler to school age. Many new nevi then appear in adolescent years due to hormonal changes and sun exposure. New nevi continue to appear in early adult years, but as one gets older new moles eventually stop occurring. Also, with age, older flat brown moles become elevated soft light brown or pink growths. The total number of moles one will develop is determined by one's skin type (fairer skinned people tend to develop more nevi than darker skinned individuals) and especially by one's lifetime sun exposure. The more sun exposure and sunburns that occur, the more moles develop and the greater one's skin cancer risk is increased.

Normal benign moles exhibit a single uniform color, symmetric round or oval shape and are generally small in size. Moles that show mixtures of colors, asymmetric or irregular shapes and just plain look different from all other moles are to be regarded as suspicious. However, some normal moles occasionally will demonstrate mild color variations. It is the degree of color or shape changes that is important. A mole that shows suspicious changes should be surgically removed and biopsied (examined under a microscope). After biopsy, a mole will be placed into one of three categories: normal, dysplastic or cancerous (malignant melanoma).

A dysplastic mole is considered still benign and not a skin cancer. However, dysplastic moles have a higher risk of someday becoming cancer (melanoma) and therefore need to be removed. Dysplastic moles usually exhibit some color variation or asymmetrical changes. People who get many dysplastic moles are at much higher risk or developing melanoma and therefore need regular skin cancer screening examinations every 6-12 months. Also, people who have family members who have had melanoma or dysplastic nevi are also at higher risk. If you have such risk factors, then you should also do skin self-examinations monthly, looking for moles that are changing in shape or color. Keep in mind that most melanomas develop gradually in otherwise normal areas of the skin. Only a small subset of melanomas develop from pre-existing moles.

The single most important activity you can do to help minimize your risk for dangerous moles is to regularly protect your skin from the damaging effects of the sun. Avoid exposure to the midday sun from 10 AM to 3 PM. Look for shaded areas. Wear protective broad-brimmed hats and clothing. Use high SPF sunscreens (20-40) on any exposed areas of skin and reapply sunscreen every 2-3 hours while outdoors. With proper sun protective behavior and regular skin examination, dangerous moles can be avoided or at least detected and removed early, long before they would present a serious threat to your health. Make skin protection part of your daily healthy lifestyle.

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