A. Asymmetry - if you draw a line through the middle of a mole or beauty mark, the two sides should be symmetrical or mirror images. B. Borders - Melanomas often have irregular borders that can be notched or blurred whereas benign moles have smooth, even borders. Border irregularity is probably the single most predictive warning sign since it is present in most melanomas. C. Color - melanomas exhibit a variety of shades of browns and black and often times contain areas that may be bluish or reddish. If a lesion is truly black, it should be considered suspicious.
Benign moles are tan or brown with relatively uniform color.
E. Enlargement - any mole or beauty mark that shows significant change in size should be regarded as suspicious. Other features to watch for are change in elevation, ulceration or bleeding. Melanoma is the most serious of skin cancers because of its capacity to spread to other areas of the body. There are a number of factors that may contribute to skin cancer and melanoma susceptibility. Geography is a major factor.