But it is a risk factor that is important to know about. We avoid smoking because we know it is a risk factor, and we should avoid the sun as well. A high number of nevi is a known risk factor for melanoma, even if the moles are not atypical. Studies done in Australia have shown that adult melanoma can be reduced by protecting the skin in childhood. Some pigmented areas of the skin are more dangerous than others.
Freckles are simply darkenings of the top layer of skin, with no potential for malignancy.
Moles, however, are composed of nevus cells that have migrated into the skin and are pigmented. Many of these moles are harmless, but moles with certain characteristics may be premalignant or malignant and should be examined by a physician. A normal mole is brown, tan, or black. It is evenly colored, and may be flat or raised, and round or oval with sharply defined borders. Moles usually stay the same size, shape, and color, although they may fade in older persons.