A common mole (nevus) is a growth on the skin that develops when pigment cells (melanocytes) grow in clusters. They are usually about 5 millimeters wide. These growths are usually found above the waist, on areas exposed to the sun, but are seldom found on the scalp, breast or buttocks. They are usually pink, tan or brown and have a distinct edge. People who have more than 50 common moles, have a greater chance of developing a dangerous type of skin cancer known as melanoma, although most common moles do not turn into melanoma.
A dysplastic nevus is an unusual mole that often is large and flat and does not have a symmetric round or oval shape. People that have many dysplastic nevi have a greater chance of developing melanoma, but most dysplastic nevi do not turn into melanoma.
If the color, size, shape or height of a mole changes or if it starts to itch, bleed or ooze, or if a mole doesn’t look like the others, one should tell their doctor. The only way to diagnose melanoma is to remove tissue and check for cancer cells.