Overview of Blood Vessel Disorders
The blood supply in the skin (cutaneous blood supply) is delivered by an interconnecting network of small arteries (arterioles), veins (venules), and tiny vessels called capillaries that connect the arterioles to the venules.
In the embryo, certain cells are responsible for stimulating blood vessel development. Simple tubelike blood vessels form first and then develop fully through the process called angiogenesis. The vasculature, or blood vessel network, is the first organ to begin developing in the embryo. Development of the vascular system continues until adulthood.
Some blood vessel disorders are the result of the overreproduction of blood vessel cells. For example, hemangioma, which typically appears soon after birth, goes through a period of rapid growth in which the blood vessel cells multiply excessively. During the period of regression during which the tumor shrinks and the skin eventually returns to a normal or near normal appearance (called involution) of these tumors, the cells gradually die off.
Other blood vessel disorders occur from vascular malformations essentially errors in development that occur between the 4th and 10th weeks of pregnancy. Most vascular malformations, such as port-wine stains, are present at birth, although some manifest years later. They tend to grow at a rate that is proportionate with the patient; however, periods of more rapid development can occur.