Benign moles often appear during the first decades of life and are characterized as round or regular shaped and brown, reports the Skin Cancer Foundation. On the other hand, melanoma is often irregularly shaped, may not be pigmented and frequently changes in size, color and appearance over time.
Benign moles may occur as a result of sun exposure, reports the Skin Cancer Foundation. These moles may be either flush to the skin or elevated, and pop up early in life. They are round or regular shaped, usually have a brown pigmentation and do not change in appearance over time. Melanoma, on the other hand, can be either pigmented or nonpigmented. Within one melanoma spot, gradations of pigmentation can exist. In addition, melanoma grows over time, sometimes rapidly, and the edges of the growth are often irregular and asymmetrical. Melanomas commonly begin flush to the skin and may become elevated over time or otherwise change in appearance. These malignant growths may become itchy or begin to form a crust or even bleed.
Certain individuals are at a higher risk of developing skin cancer, adds the Skin Cancer Foundation. These people have high numbers of both atypical and benign moles, and are classified as having atypical mole syndrome. Such individuals have over 100 moles, at least one atypical mole and at least one mole greater than 8 millimeters in diameter. People with these three characteristics are at a much higher risk for developing melanoma. This syndrome can be genetically linked and is called familial atypical multiple mole melanoma syndrome when such individuals have one or more first-degree relatives with melanoma.