Moles are small, usually dark, skin growths that develop from pigment-producing cells in the skin (melanocytes).
Most people have some moles, but the tendency to develop atypical moles is sometimes hereditary.
Moles and atypical moles that change significantly should be biopsied for possible melanoma.
Most noncancerous (benign) moles do not require treatment, but moles that are uncomfortable or a cosmetic concern can be removed with a scalpel and local anesthetic.
Moles vary in size from small dots to more than 1 inch (about 2.5 centimeters) in diameter but are usually less than 1 centimeter and tend to be less than 6 millimeters (about 1/4 inch). Almost everyone has a few moles, and many people have large numbers of them. People who have more than 50 moles have a somewhat increased risk of melanoma, a cancerous (malignant) growth of melanocytes. They should self-monitor for changes in their moles (see the ABCDEs of melanoma) and also have them examined periodically as part of their primary care.
Moles may be flat or raised, smooth or rough (wartlike), and may have hairs growing from them. Moles are typically skin-colored, yellow, brown, blue-gray, or nearly black. They may be red at first but often darken.
Moles commonly develop in childhood or adolescence, and existing moles often enlarge (in proportion to the body's growth) and may darken. In some people, moles continue to develop throughout life. Moles can appear anywhere on the body. Moles respond to changes in hormone levels in women and may darken during pregnancy. Once formed, moles remain for a lifetime and get less pigmented and more raised or fleshy with time. In fair-skinned people, moles occur more commonly on sun-exposed areas of the skin.