Moles occur when cells in the skin grow in a cluster instead of being spread throughout the skin. These cells are called melanocytes, and they make the pigment that gives skin its natural color. Moles may darken after exposure to the sun, during the teen years, and during pregnancy.
Often the first sign of melanoma is a change in the shape, color, size, or feel of an existing mole. Melanoma may also appear as a new colored area on the skin. The “ABCDE” rule describes the features of early melanoma (2, 5): Asymmetry.
A is for Asymmetry
Normal moles are symmetrical in shape, meaning if you were to draw a line down the middle, both halves would look the same. Asymmetrical moles are abnormal and should be checked by a doctor.
B is for Border
Border that is irregular: The edges are often ragged, notched, or blurred in outline. The pigment may spread into the surrounding skin.
C is for Color
Moles are often a brownish colour, although some may be darker or skin-coloured. They can be flat or raised, smooth or rough, and some have hair growing from them. Moles are usually circular or oval with a smooth edge.
D is for Size
A normal mole is usually an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are generally less than 6 millimeters (about ¼ inch) across (about the width of a pencil eraser).
E is for Evolving
The mole looks different from others and/or is changing in size, colour or shape.
Be sure to show your doctor any areas that concern you and ask your doctor to look at areas that may be hard for you to see. It’s sometimes hard to tell the difference between melanoma and an ordinary mole, even for doctors, so it’s important to show your doctor any mole that you are unsure of.