Port Wine Stain
A "Port Wine Stain" is a type of birthmark, sometimes fairly large, that is dark red in color, hence the reference to Port wine. It is caused by type of vascular anomaly (a capillary malformation in the skin). This can be a symptom of of various syndromes such as s Sturge–Weber syndrome or Klippel–Trénaunay–Weber syndrome. This type of birthmark can be seen on the face, arms or legs. In recent years you have probably seen Russian Premiere Mikaiol Gorbachev who has a very prominent port wine stain on his head and face.