The ABCDs of moles and melanomas

July 1, 2007

When you inspect moles, pay special attention to their sizes, shapes, edges, and color. A handy way to remember these features is to think of the A, B, C, and D of skin cancer-asymmetry, border, color, and diameter.

People at high risk of developing melanoma are those who have:

  • A family history of melanoma, or who have had a melanoma in the past

  • Unusual moles on the skin, or changing moles

  • Fair skin, light hair and eye color, and who sunburn easily or tan with difficulty

  • A record of painful or blistering sunburns as children or in their teenage years

  • Indoor occupations and outdoor recreational habits

When you inspect moles, pay special attention to their sizes, shapes, edges, and color. A handy way to remember these features is to think of the A, B, C, and D of skin cancer-asymmetry, border, color, and diameter.

Some forms of early malignant melanoma are asymmetrical, meaning that a line drawn through the middle will not create matching halves. Moles are round and symmetrical.The borders of early melanomas are frequentlyuneven, often containing scalloped or notched edges. Common moles have smooth, even borders.
Different shades of brown or black are often the first sign of a malignant melanoma. Common moles usually have a single shade of brown.Common moles are usualy less than 6 mm in diameter (1/4 in.), the size of a pencil eraser. Early melanomas tend to be larger than 6 mm.