ATYPICAL MOLES are unusual-looking benign (noncancerous) moles, also known as dysplastic nevi (the plural of “nevus,” or mole). Atypical moles may resemble melanoma, and people who have them are at increased risk of developing melanoma in a mole or elsewhere on the body. The higher the number of these moles someone has, the higher the risk. Those who have 10 or more have 12 times the risk of developing melanoma compared with the general population.
Heredity appears to play a part in the formation of atypical moles. They tend to run in families, especially in Caucasians; about 2 to 8 percent of Caucasians have these moles. Those who have atypical moles plus a family history of melanoma (two or more close blood relatives with the disease) have a very high risk of developing melanoma. People who have atypical moles, but no family history of melanoma, are also at higher risk of developing melanoma compared with the general population. So are those with 50 or more normal moles. All of these high-risk individuals should practice rigorous daily sun protection, perform a monthly skin self-examination head to toe and seek regular professional skin exams.
Some people have so many normal and atypical moles that they are classified as having atypical mole syndrome. People with “classic” atypical mole syndrome have the following three characteristics:
- 100 or more moles
- One or more moles 1/3 inch (8 mm) or larger in diameter
- One or more moles that are atypical.
At even higher risk of developing melanoma are those with familial atypical multiple mole melanoma syndrome (FAMMM). These people not only have atypical mole syndrome, but also one or more first- or second-degree relatives with melanoma. While atypical moles often arise in childhood, they can appear at any time of life in people with FAMMM.