Melanoma is diagnosed by five aspects of atypical moles, according to WebMD. These include asymmetry, border irregularity and color. Diameter and evolution may also indicate the presence of disease. Examining atypical moles based on these five criteria is known as using the ABCDE rule for detecting melanoma.
Asymmetry means the two halves of a mole do not match, notes WebMD. Mole edges that are notched, blurred or ragged exhibit border irregularity. A mole with nonuniform pigmentation suggests melanoma based on color. The mole has a mottled appearance with a shade of black, brown or tan present, as well as dashes of blue, white and red. Color distribution changes, particularly the presence of color that spreads from the mole's edge into surrounding skin, indicate early melanoma.
Moles larger than the approximate size of a pencil's eraser, or that grow, are concerning. Evolution in the shape, size or color of moles is important. Symptoms of a mole, such as tenderness or itching, that change, as well as surface developments, particularly bleeding, are noteworthy. Atypical moles are abnormal moles, also known as dysplastic nevi, explains WebMD. While they themselves are not malignant, their presence warns of a tendency to develop melanoma. There can be an inherited predisposition to developing atypical moles.