Moles consist of nests of melanocytes—the pigment producing cells in the skin. Moles exist on almost every individual and can occur anywhere on the body including the scalp, lips, nails and soles. Moles develop in the first few decades of life but some people are born with a mole and this is called a “congenital nevus.” Birth moles should grow proportionately with the body and be monitored regularly. Large birth moles carry a small but known risk of developing melanoma. Benign moles are referred to as “melanocytic nevi.” These can be pink, tan, blue, brown or black, flat or raised. Some people have a familial tendency to develop many moles. Having approximately 40-50 moles or more increases the chance of developing melanoma. Heavy sun exposure also increases the number of moles.
Any changes in a mole or the appearance of a new mole should be checked out by your dermatologist. A good rule to follow is the “ABCDE” rule. Any change following the “ABCDE” rule may mean that the mole could be transforming into a “dysplastic nevi” (atypical mole) or even melanoma. An explanation of the ABCDEs rule is explained below:
A = Asymmetry: Moles should be symmetrical. If one side does not match the other side then have it examined.
B = Border: The border of the mole should be regular, sharp, and well-defined.
C= Color: Uniform color should exist in the mole. More than 2 colors may indicate an atypical mole.
D = Diameter: Moles should usually be 6 mm or smaller in diameter. This is about the size of an eraser on a pencil. Some moles, especially birth moles, can be bigger than 6 mm and are still benign.
E = Evolution: New or evolving moles should be examined by a physician. These changes can include changes in how the mole looks or new symptoms to the mole including itching, pain, bleeding, or ulceration.
Atypical moles or “dysplastic melanocytic nevi” are unusual moles that look atypical both clinically and under the microscope. Dysplastic nevi are genetically inherited. The presence of dysplastic nevi greatly increases the risk of melanoma. Dysplastic nevi can be precursor lesions to melanoma and those with > 10 dysplastic nevi have a higher risk or getting melanoma. Individuals with atypical moles should get to know their moles and be examined every 6-12 months by a dermatologist.