Most adults have a few common moles, but some types of moles have a higher than average risk of becoming cancerous and developing into malignant melanoma.

Melanoma

Moles at greater risk of becoming cancerous include:

  • Large moles present at birth. Large moles that are present at birth are called congenital nevi. These moles may increase your risk of malignant melanoma, a deadly form of skin cancer.
  • Atypical moles (dysplastic nevi). Moles that are larger than 1/4 inch (about 6 millimeters) — or larger than the diameter of a pencil eraser — and irregular in shape are known as atypical (dysplastic) nevi. These moles tend to be hereditary. They're frequently described as looking like fried eggs because they usually have dark brown centers and lighter, uneven borders. If you have dysplastic nevi, you have a greater risk of developing malignant melanoma.
  • Numerous moles. If you have many moles — 20 or more — you're at a greater risk of developing melanoma.
Dec. 06, 2011