capillary malformation
(KA-pih-layr-ee MAL-for-MAY-shun)
An overgrowth of capillaries (small blood vessels) near the surface of the skin. Capillary malformations are present at birth and look like pink, red, or purple patches on the skin. They usually appear on the face or neck but can occur anywhere. Large capillary malformations are sometimes called port-wine stains, which tend to grow and become darker over time. They may also become raised or bumpy. Most capillary malformations do not cause health problems, but some may be associated with certain rare conditions such as Sturge-Weber syndrome, Klippel-Trenaunay syndrome, and Proteus syndrome.