Picture of Port-Wine Stain (Neck)
Port Wine Stain. A port-wine stain is a permanent and often unsightly type of vascular birthmark. They are an abnormal distribution of blood vessels but it's unclear what causes them, and they can't be prevented. They are generally harmless but if they are cause for concern over location or the subject of embarrassment, they may be treated with multiple laser surgeries.
Text Source: Mayo Clinic
Medline Plus / National Library of Medicine