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Your child’s capillary malformations do not hurt or itch. They are usually pink and flat early in life. Over time, they will darken to red or purple. Their color led to the common name of port wine stain.

As your child ages, the skin of the port wine stain may also thicken and develop a bumpy texture or nodules.

Port wine stains can be small, or they might cover a large portion of the body. They are often located on the face. They also appear in other places such as on the top of the head, the neck, the upper chest, or the limbs.

When to See a Doctor

Your child’s capillary malformation (or port wine stain) should be checked by their doctor regularly. The doctor will want to measure its size and examine its shape and how it looks as your child grows.

You should also take your child to see the doctor if the birthmark:

  • Changes
  • Bleeds
  • Cracks
  • Gets infected
  • Affects your child’s vision


Capillary malformations (or port wine stains) are caused by capillaries in the skin that did not form the right way. Doctors think that it happens during the first trimester of pregnancy. A capillary is the smallest of all the blood vessels. As more and more blood flows through them, they get bigger, which is called dilating.

Doctors think that when capillaries dilate in a way that makes the blood inside them more visible at the surface of the skin, we see a port wine stain. Since the capillaries don’t get better on their own, the birthmark does not fade over time.

Diagnosis and Tests

Sometimes it is hard to tell what kind of mark your child has. Your child’s doctor should be able to tell by how it looks as your child grows. Capillary malformations start as flat patches that are pink or red and get darker.

In rare cases, your child’s doctor might order a biopsy to find out if the mark is a capillary malformation. During a biopsy, a very small sample of your child’s skin will be taken and tested in a lab.

Related Conditions

Two other kinds of vascular birthmarks are hemangiomas and macular stains, and they might seem similar at first. Unlike a port wine stain that is flat, a hemangioma sits on top of the skin like a bump. Macular stains tend to fade, and many disappear all the way.

If your child has a large port wine stain or it is on your child’s face, the doctor may want to have your child tested for other problems. Some of the usually rare conditions that can be marked by the presence of a port wine stain include:

  • Sturge-Weber [STERJ VEY-ber] syndrome, which can cause seizures and intellectual disability and is also marked by bulges called lymphatic malformations (sometimes called cystic hygromas)
  • Klippel-Trénaunay [KLI-puhl trey-NOU-ney] syndrome, which can cause varicose veins and soft tissue problems

Sometimes when a port wine stain is on a limb, it grows to be a different size than the opposite limb. This can be a symptom of Klippel-Trénaunay syndrome.


Capillary malformations (or port wine stains) are often harmless. You can care for your child’s port wine stain in the same way as the rest of their skin. However, the birthmark may tend to get dry, so you may need to moisturize it more often.

Unless there is a related condition, these birthmarks do not need medical treatment. You or your child might want to try to cover the birthmark with make-up, try laser therapy, or both. Laser therapy is the safest treatment and is least likely to cause scarring.

Laser therapy can lighten the area though it may not remove the whole birthmark. Sometimes it does not remove any of the mark, or the mark comes back after a while and laser therapy can be tried again.

The sooner your child is treated, the better their outcome might be. Babies have smaller blood vessels, making it easier to treat their port wine stains. Laser therapy can be done on children as young as 6 months old, though very young children may need anesthesia [ann-ess-TEE-see-uh].

You should ask your child’s doctor about what timing that is right for your child should you opt for laser treatment.


Capillary malformations cannot be prevented. They are not caused by things that the mother did or ate while she was pregnant.

Doctors do not think that these birthmarks run in families. Having one child with a capillary malformation or port wine stain does not increase your chances of it happening again.

What is Capillary Malformation?

A capillary [KAP-uh-ler-ee] malformation is more commonly called a port wine stain. It is also called nevus flammeus [NEE-vuhs FLEY-mee-us]. It is a kind of vascular [VAS-kyuh-ler] birthmark that appears on about 3 of every 1000 babies.

A vascular birthmark is caused by blood vessels in the skin that did not form the right way. Capillaries are the smallest of the blood vessels. Most of the time, port wine stains are harmless and painless.

A port wine stain can be seen at birth. It is most often on a child’s face. It can also be on the top of the head, the neck, or the upper chest.

It is flat and can be pink, red, or purple. It might get darker and thicker with time. It will get bigger as it grows with your child. It will not go away on its own, but it might fade.

Because it is close to the top of the skin, a port wine stain might bleed more easily than the skin around it. That puts your child at more risk for infection.

In rare cases, port wine stains can be linked to problems with the brain or development. This happens most often when the birthmark is on the eyelid or forehead. Also, having the birthmark on the eyelid puts your child at risk of developing glaucoma [glaw-KO-muh] later in life.

You can care for your child’s port wine stain in the same way as the rest of their skin. However, the birthmark may tend to get dry, so you may need to moisturize it more often.