Moles (Nevi)

What Is It?

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.

Symptoms

Moles can vary in color. They can be flesh-colored, yellow-brown or dark brown. They also can be flat or raised and can be smooth, hairy or warty. Although moles usually are harmless, in some cases they can become cancerous, causing a potentially deadly tumor called malignant melanoma. For this reason, it is important to monitor moles and have them examined by a dermatologist if they:

  • Get larger suddenly

  • Develop an irregular border

  • Become darker or inflamed

  • Show spotty color changes

  • Begin to bleed, crack or itch

  • Become painful

Moles called atypical moles, or dysplastic nevi, have somewhat different physical characteristics and sometimes run in families. They are more likely than common moles to turn into cancer. People with multiple dysplastic nevi and melanoma in two or more first-degree relatives have 25 times the risk of developing melanoma. This is called the dysplastic nevus-melanoma syndrome.

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