Moles are small, pigmented spots on the skin that usually appear during childhood or adolescence, although they are sometimes present at birth. They are composed of clusters of pigmented cells called melanocytes. People may develop more moles during adolescence and pregnancy, and existing ones may enlarge or darken somewhat during these times. Despite such changes, moles should always remain:
Evenly pigmented — The color is the same across the mole.
Sharply demarcated — The edges of the mole are clear-cut.
Symmetrical in shape and color — All parts of the mole look similar.