Moles, also known as nevus, and birthmarks are benign pigmented spots or patches of skin that range in color from tan, brown and black (moles) to red, pink or purple (vascular lesions, such as strawberry hemangiomas or port wine stains). 

Most moles appear on the skin during childhood and adolescence. Moles will grow as the child (or teen) grows. Some moles will darken, and others will lighten. These changes are expected and seldom a sign of melanoma, the most-serious form of skin cancer.

For adults, new moles and changes to existing moles can be a sign of melanoma. Caught early, melanoma is highly treatable. 

Development of moles is mostly hereditary, but sun exposure can increase the number of moles that a person develops. While most melanoma develops in unrelated sites, it can develop in a preexisting mole, so it is important to examine your moles on a regular basis to look for any changes. 

Though most congenital nevi (moles one is born with) are harmless, some of them may develop into skin cancer. Moles exhibiting any of the following warning signs should be examined by a board certified dermatologist immediately: 

• > 6 millimeters
• Irregular borders
• Itches or bleeds
• Rapidly changes in color, size or shape
• Has multiple colors
• Difficult to monitor locations (such as the scalp)

There are several different types of moles:

• Atypical or dysplastic nevi are moles that have somewhat irregular cells under the microscope. While these lesions are benign, they do indicate that you may have an increased risk of developing a melanoma, especially if you have family members with a history of melanoma.
• Congenital nevi are moles that appear from birth. If these moles are large (>20cm) or if there are many, you may have an increased risk of developing melanoma.

A vast majority of moles are benign, however if they are irritated or changing, they can be easily removed with a local surgical excision or shave removal. If there is any question about potential cancer, the mole will be sent to a pathologist for further investigation.

For more information on moles, please visit aad.org.