Otherwise known as unusual moles that may resemble melanoma. People who have 10 or more of these moles have 12 times the risk of developing melanoma. Those who have dysplastic nevi plus a family history of skin cancer have an extremely high risk of melanoma.
The Classic Atypical Syndrome
People with a classic atypical mole syndrome have the following three characteristics:
- 100 or more moles
- One or more moles 8 mm (1/3 inch) or larger in diameter
- One or more moles which are atypical.
SHAPE: often asymmetrical: A line drawn through the middle would not create matching halves.
BORDER: irregular and/or hazy—the mole gradually fades into the surrounding skin.
COLOR: variation and irregularity with subtle, haphazard areas of tan, brown, dark brown, red, blue or black.
DIAMETER: generally larger than 6 mm (1/4 inch), the size of a pencil eraser, but may be smaller.
LOCATION: most commonly on the back, chest, abdomen and extremities; may also occur on normally unexposed areas such as the buttocks, groin or female breasts, as well as on the scalp.
GROWTH: Enlargement of a previously stable mole or appearance of a new mole after ages 35–40 should raise suspicion.
SURFACE: Central portion often is raised, whereas the peripheral portion is usually flat, sometimes with tiny “pebbly” elevations.
APPEARANCE: greatly varied; dysplastic nevi often look different from one another.
NUMBER: From a few to well over 100 dysplastic nevi may be present.
Here’s a quick visual guide from Cancer.Gov:
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