Most people have moles and they are almost always harmless. Although the first sign of a melanoma is often a change in a mole, it does not necessarily mean that all changes are melanomas.

A = Asymmetry.

Melanomas are frequently asymmetrical: the shape of one half does not match the other.

B = Border.

Melanomas frequently have uneven or irregular borders (ragged or notched edges). 

C = Color.

Melanomas often contain multiple shades of brown or black but can sometimes be mixed with white, gray, blue, or red. Some melanomas will show a loss of color in a preexisting mole or in the area surrounding the mole. 

D = Diameter.

Melanomas are often larger than 6 mm (1/4 inch) in diameter. However, with increased awareness about early detection, about 30% of melanomas are found when they are less than 6 mm in diameter. 

E = Evolution.

Any change. Melanomas typically have shown some evidence of change in the months prior to diagnosis.