Sometimes the appearance of a birthmark catches a new parent by surprise. Physicians are often quick to offer reassurance that most birthmarks are harmless, and many will shrink or disappear over time. Although that's true, a birthmark can also be the key to early identification of a rare disorder called Sturge-Weber Syndrome.

Dr. Anne Comi, director of the Hunter Nelson Sturge-Weber Center at Kennedy Krieger Institute, tells us how to determine when a birthmark might be a sign of something more.

  • Birthmarks are extremely common - one in 10 children have them. They can come in a variety of colors, shapes and sizes and are either vascular - an accumulation of blood vessels underneath the skin - or pigmented, discolored patches of pigment. It is important to recognize which category your child's birthmark falls under for screening purposes.

  • One of the most common vascular birthmarks is known as a port-wine birthmark. Pink or red in color, it is often found on the face and consists of abnormal capillary venous blood vessels in the skin.

  • The location of a birthmark matters. When a port-wine birthmark is located on the forehead or upper eyelid, it raises an important red flag for the possibility of the syndrome. About 10 to 35 percent of children born with a port-wine birthmark in this location will have the disorder.

  • For those with Sturge-Weber Syndrome, the port-wine birthmark is the first outward expression of the disorder, which later in childhood frequently develops to include seizures, neurologic impairments, visual problems and glaucoma, as well as learning difficulties.

  • In Sturge-Weber Syndrome, abnormal blood vessels are also present in the eye and the brain. Abnormal blood flow in the brain and the eye causes the neurologic and vision impairments. Recognizing the risk of Sturge-Weber Syndrome at birth offers the best chance for early monitoring and intervention.

In addition to Sturge-Weber Syndrome, birthmarks are sometimes associated with other health problems. Consult with your pediatrician about whether this might be the case for your child.