A vascular malformation is a type of birthmark, or congenital (present at birth) growth, made up of arteries, veins, capillaries, or lymphatic vessels. There are several different types of malformations and they are named according to which type of blood vessel is predominantly affected. A vascular malformation is also known as an arteriovenous malformation and vascular gigantism.
Vascular malformations are present at birth and enlarge proportionately with the growth of the child. They do not involute spontaneously and may become more apparent as the child grows.