What are Dysplastic Nevi?
Dysplastic nevi or atypical moles are unusual-looking benign (noncancerous) moles. 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.
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.
We often identify an atypical mole by the same classic “ABCDE” characteristics used to identify a possible melanoma:
- “A” is for Asymmetrical. Look for moles with an asymmetrical shape, such as two very different looking halves. Unlike common moles, atypical moles are often asymmetrical: A line drawn through the middle would not create matching halves.
- “B” is for Border. Watch for moles with irregular, ragged or blurred borders. While common moles usually have regular, sharp, well-defined borders, the borders of atypical moles tend to be irregular and/or hazy — the mole gradually fades into the surrounding skin. These are characteristics of melanoma.
- “C” is for Color. Watch for moles that have different colors throughout, or contain shades of brown, black, blue, or white, or red. Common moles are most often uniformly tan, brown or flesh-colored, but atypical moles have varied, irregular color with subtle, haphazard areas of tan, brown, dark brown, red, blue or black.
- “D” is for Diameter. Look for moles that are larger than the eraser of a typical #2 pencil. Atypical moles are generally larger than 6 mm (¼ inch), but may be smaller.
- “E” is for Evolution. Monitor for changes over time. For example, watch for a mole that grows or changes shape or color. Enlargement of or any other notable change in a previously stable mole, or the appearance of a new mole after age 40, should raise suspicion.