Reviewed by Brian R. Robinson, MD
A port wine stain (PWS) is a vascular birthmark that is caused by blood passing through an unusually dense network of blood vessels just below the skin’s surface. The PWS varies in size from person to person; some have a small mark known as a “stork bite”, while others are covered over most of the body. The color ranges from light pink to dark purple.
PWS occurs in three out of 1,000 births and is noticeable on newborn babies. Over time a PWS may increase tissue mass and become raised, darker, and grape-like. The presence of PWS is often emotionally troubling for children and adults, because of the prominence of the birthmarks, especially when they appear on parts of the body that are always or frequently exposed, such as the face.
PWS may be one of a group of symptoms and signs in which case it is considered to be part of a syndrome such as Sturge-Weber syndrome or Klippel-Trenaunay-Weber syndrome, both of which are congenital vascular disorders.