Moles (nevi) are naturally occurring groups of cells which are seen on the skin of all people. They vary from being flat to raised, brown, black, pink to flesh-colored. The average person has between fifty to one hundred moles on their body. If they are present at birth, we call them congenital nevi (birthmarks). Other types of moles (acquired nevi) develop throughout youth and young adulthood.

Most moles are benign (normal/non-cancerous), however, characteristics of a type of skin cancer need to be differentiated if the moles have an unusual appearance. Melanoma often develops in a pre-existing mole that begins to change or a new mole. It is estimated that 20% to 40% of melanomas arise from an atypical mole. This is why it is so important to be familiar with the moles on your body and perform regular self-examinations of your skin. When looking at moles, keep in mind the ABCDs of Melanoma Detection:

1. Asymmetry. If you could fold the lesion in two, the two halves would not match.
2. Border. Melanomas often have uneven or blurred borders.
3. Color. Melanoma typically is not one solid color; rather it contains mixed shads of tan, brown, and black. It can also show traces of red, blue or white.
4. Diameter. While melanomas are usually greater than 6 millimeters (about the size of a pencil eraser) when diagnosed, they can be smaller.

If you notice a mole different from others, or which changes, itches, or bleeds even if it is smaller than 6 millimeters, you should see a dermatologist.

It is important to realize that a mole may have some of the characteristics described above and not be a melanoma. A biopsy is often necessary to distinguish an atypical mole from a melanoma.