Capillary Malformations

Capillary malformations are birthmarks caused by dilated blood vessels within the skin. These birthmarks, which were historically also called port-wine stains, are present at birth and expected to remain throughout life, over time growing in proportion with the person. During childhood, capillary malformations generally appear as flat pink to dark red or purple patches on the skin. They can occur anywhere on the body but are most typically seen on the head and neck regions. With age, some may gradually become darker and thicker.

In the majority of people, a capillary malformation is an isolated birthmark on the skin, and there are no other abnormalities in the body. In some cases, capillary malformations can be associated with overgrowth of the underlying soft tissue and/or bone. In other cases, capillary malformations may be associated with a syndrome (see below for more information).


Diagnosis is typically made based on a patient’s history and physical examination. You/your child will meet with the Vascular Anomalies Center team during the initial clinic visit for a comprehensive review of the patient’s medical history, any imaging studies and/or tests that have been performed, and a complete physical examination. Although not routinely performed and rarely necessary for diagnosis, a skin biopsy will show dilated capillaries.


Laser therapy using the pulsed-dye laser may be used to treat capillary malformations on the face or other parts of the body. Laser therapy helps to lighten the color and may prevent future darkening or thickening.  The degree of improvement varies from person to person. The majority of those who undergo treatment will experience 50% to 70% lightening of the birthmark. Early treatment, especially during infancy, generally yields better results. In addition, some body parts respond better than others. For example, capillary malformations on the face and neck tend to respond better to laser therapy than those on the arms or legs.

The number of treatments required varies depending on the lesion. Treatments are usually spaced one to two months apart, and at least six to eight treatments are generally needed for optimal results. Because the procedure is painful, either a topical or general anesthetic is used.


The majority of capillary malformations are isolated findings in the skin and do not produce serious health complications.

In a minority of cases, capillary malformations are part of syndrome that may include overgrowth of tissues and a deeper venous, lymphatic or arteriovenous malformation. Klippel-Trenaunay syndrome is the combination of a capillary malformation located on an extremity, overgrowth and a deeper combined venous-lymphatic malformation. Parkes-Weber syndrome is the combination of a capillary malformation located on an extremity, overgrowth and an arteriovenous malformation. If there is concern for one of these syndromes, further imaging may be recommended.

In a small group of people, capillary malformations may be associated with abnormalities in other organs. Sturge-Weber syndrome is a condition where a capillary malformation on the face is associated with eye and brain abnormalities, including glaucoma and seizures. In some cases, a brain MRI and/or a consultation with an ophthalmologist for evaluation of glaucoma could be needed.