A capillary malformation (also known as a port-wine stain or port-wine birthmark), is a flat, sharply defined vascular discoloration of the skin. It may cover a large surface area or it may be scattered and appear as smaller spots of color. It can be found be anywhere on the body.
Capillary malformations are a group of abnormal tiny blood vessels of the skin. These vessels form incorrectly before a baby is born. Capillary malformations are not caused by any drug, medication or environmental factor that the baby may have been exposed to during the pregnancy.
A genetic change (mutation) was found in affected skin of capillary malformations, but not present in nearby normal skin. Most capillary malformations are not inherited. When a person has multiple lesions, he or she could have an inherited condition.
Another capillary vascular lesion, nevus simplex, is seen in newborn infants. This is often confused with capillary malformations. When these birthmarks appear on the forehead, eyelids, nose, or upper lip, they are called "angel kisses." When located on the back of the neck, scalp, or back, the lesions are called "stork bites." These lesions fade by 1-2 years of age. They do not require treatment.