Health Library
Capillary Malformations

What Are Capillary Malformations?

A capillary malformation (also known as a port-wine stain or port-wine birthmark), is a flat, sharply defined pink to red discoloration of the skin. A person may have one or multiple capillary malformations. These lesions may cover a large surface area or may be scattered and appear as smaller spots of color. Capillary malformations can be found be anywhere on the body.

Capillary malformations are a group of capillaries (tiny blood vessels of the skin) that form abnormally Capillary malformations have increased diameter (wider blood vessel tube) and number of capillaries, which makes the skin blood vessels more visible. These vessels form incorrectly before a baby is born. Capillary malformations are not caused by any known drug, medication or environmental factor that the baby may have been exposed to during the pregnancy.

A genetic change (mutation) has been found in affected skin of capillary malformations, but not present in nearby normal skin. Most common genetic mutations are GNAQ and GNA11. Most capillary malformations are not inherited. When a person has multiple lesions or has other family members with similar birthmarks, 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 have a typical pattern on the skin and typically fade by 1-2 years of age. They do not require treatment.

What Do Capillary Malformations Look Like?

Capillary malformations look pink, red, or purple due to an increased number and size (diameter) of blood vessels involved in comparison to normal capillaries of the skin. As your child grows, the affected blood vessels may continue to enlarge and thicken. This will cause the color of the lesion to darken. Over time, clusters of tiny, dilated venules (small vessels that collect blood from the capillary junctions and join to form veins) may give a lumpy look to the skin. The degree and length of time to develop skin thickening varies greatly. This may be delayed into early or mid-adulthood.

How are capillary malformations diagnosed?

Most capillary malformations are diagnosed by history and physical exam alone. Sometimes imaging with ultrasonography or magnetic resonance imaging (MRI) is needed to exclude similar or related conditions

What are the possible complications?

Capillary malformations can be associated with overgrowth of underlying soft tissues or bones. The color of a facial lesion can darken. Facial skin may also thicken and form nodules (become “lumpy”) over time. Inflammatory bright, red, raised lesions called pyogenic granulomas may develop on or near the birthmark and are prone to bleeding.

When the capillary malformation involves the forehead and / or upper eyelid, abnormalities of the eye and / or brain may occur (Sturge-Weber syndrome). All lesions around the eye should have routine eye exams to evaluate for glaucoma. Magnetic resonance imaging (MRI) may be used to determine if there are any brain changes related to Sturge-Weber syndrome.

Capillary malformations in the skin directly over the spine can be associated with spinal abnormalities. This can include tethering of the spinal cord. These malformations should be investigated with an ultrasound or MRI of the spine.

How are capillary malformations managed?

Several treatment approaches are used to treat capillary malformations.

Laser therapy with pulsed-dye laser is the standard treatment for capillary malformations on the face. One goal of treatment is to prevent lesions from thickening over time. Another goal is to lighten the capillary malformation. Many lesions lighten significantly after multiple treatments. Very few malformations go away completely. Usually the laser treatment results are better on the face than on the trunk or limbs. Deeper vessels do not respond as well as vessels on the skin surface. The number of treatments needed depends on the size and depth of the malformation. A topical anesthetic and/or general anesthesia are used because the procedure can be painful.

Surgical procedures may be considered when there is too much soft tissue or bone enlargement. Surgery and skin grafting may be recommended if the skin is very thick and laser therapy is not successful.

There are no beneficial medication options currently. Investigational medications are currently being developed and tested.

What are the risks and side effects of treatment?

There are risks for both laser therapy and surgery. The risks of pulsed-dye laser are low if treatment is performed by an experienced doctor. Rarely, blistering may occur, resulting in scarring. Pigment changes, either lightening or temporary darkening of the skin may also occur. Even with laser treatment, a capillary malformation may return after several years.

The risks of surgery depend upon the type of surgery performed. General risks of surgery include infection, bleeding and scarring. A risk of skin grafting is loss of the graft.

Last Updated 03/2022

Reviewed By Adrienne Hammill, MD, PhD, and Kiersten Ricci, MD

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