Information for Patients
Birthmarks are abnormalities of the skin that are present when a baby is born. There are two types of birthmarks. Vascular birthmarks are made up of blood vessels that haven't formed correctly. They are usually red. Two types of vascular birthmarks are hemangiomas and port-wine stains. Pigmented birthmarks are made of a cluster of pigment cells which cause color in skin. They can be many different colors, from tan to brown, gray to black, or even blue. Moles can be birthmarks.
No one knows what causes many types of birthmarks, but some run in families. Your baby's doctor will look at the birthmark to see if it needs any treatment or if it should be watched. Pigmented birthmarks aren't usually treated, except for moles. Treatment for vascular birthmarks includes laser surgery.
Most birthmarks are not serious, and some go away on their own. Some stay the same or get worse as you get older. Usually birthmarks are only a concern for your appearance. But certain types can increase your risk of skin cancer. If your birthmark bleeds, hurts, itches, or becomes infected, call your health care provider.
Moles are growths on the skin. They happen when pigment cells in the skin, called melanocytes, grow in clusters. Moles are very common. Most people have between 10 and 40 moles. A person may develop new moles from time to time, usually until about age 40. In older people, they tend to fade away.
Moles are usually pink, tan or brown. They can be flat or raised. They are usually round or oval and no larger than a pencil eraser.
About one out of every ten people has at least one unusual (or atypical) mole that looks different from an ordinary mole. They are called dysplastic nevi. They may be more likely than ordinary moles to develop into melanoma, a type of skin cancer. You should have a health care professional check your moles if they look unusual, grow larger, change in color or outline, or in any other way.
NIH: National Cancer Institute