Vascular malformations are less common than hemangiomas but, because there are so many different types of vascular malformations, it is difficult to give an accurate estimate of the incidence. If they are present at birth, frequently the only evidence is a faint red mark. Shortly after birth they grow rapidly, out of proportion to the growth of the child. They then undergo a period of involution, during which they spontaneously become smaller and lighter in color. This gradual process of involution may take several years.
Some hemangiomas disappear completely and others undergo only a partial involution.
Vascular malformations, on the other hand, do not have a rapid growth phase and enlarge proportionately with the growth of the child. They never regress spontaneously and may become more apparent later in life. Some malformations, such as port-wine stains, cause only a change in skin color whereas other malformations are large, bulky growths which can distort normal structures. The various types of malformations have different characteristics, different growth pattems, different associated problems and different treatments. Once again, this reinforces the need to make an accurate diagnosis.