Port-wine stains are birthmarks. They are most commonly located on the face but can also appear anywhere on the body. Port-wine stains are caused by overly-dilated blood capillaries close to the surface of the skin. The resulting collection of the blood gives port-wine stains their distinctive appearance, which can range from light pink to purple in color. Port-wine stains are usually benign but can also be a sign of underlying health conditions. Your primary health care provider can determine if additional testing is necessary. In the meantime, port-wine stain appearance can be improved. At SF Bay Cosmetic Surgery Medical Group we help improve the appearance of port-wine stains and other vascular irregularities.