Vascular malformations are a type of birthmark. They are present at birth (congenital) and are made up of arteries, veins, capillaries or lymphatic vessels. They enlarge proportionately with the growth of the child and, unlike hemangiomas (a benign tumor of the skin present at birth), they do not diminish as the child grows. Vascular malformations are named according to the blood vessels involved. They include: