Source: wikibot/port-wine-stain
= Port-wine stain
{wiki=Port-wine_stain}
A port-wine stain is a type of vascular birthmark characterized by a flat, red or purple discoloration of the skin. These marks are caused by an abnormal proliferation of blood vessels, specifically capillaries, just beneath the surface of the skin. The name "port-wine stain" comes from the deep red color that resembles port wine.