Parkes Weber Syndrome

PWS is an exceptionally rare congenital (present at birth) vascular anomaly that results in a child having a large number of abnormal blood vessels. It’s similar to the more common Klippel-Trenaunay syndrome (KTS) and is treated in much the same way.

In contrast to children who have KTS, children with PWS have arteriovenous malformations (AVM) — abnormal connections between the arteries and veins in the affected limb that can cause heart failure.

There is no cure for Parkes Weber syndrome; the most effective way to manage the condition is to treat the symptoms it causes.

No single specialist can manage PWS and its associated problems, because different interventional techniques and surgical procedures are often needed. That's why the first step in managing PWS is to have your child evaluated by members of an experienced interdisciplinary vascular anomalies team.

Parkes Weber syndrome affects different children in different ways. One child may have a mild form with a small capillary malformation and one hand or foot slightly larger than the other. Another child may have a capillary malformation that runs from her chest down her leg, lots of swelling, heart problems, and one limb that is much larger than the other.

Some possible symptoms of PWS include:

• A flat, pink, warm birthmark called a port-wine birthmark, caused by a capillary malformation on your child’s skin
• Frequent or recurrent bleeding, from abnormal capillaries near the surface of the skin
• Cellulitis (infections in the skin)
• Hypertrophy — swelling and overgrowth — of a limb (usually a leg)
• Pain — often severe — in the affected limb
• Heart problems from increased blood flow through an arteriovenous malformation

In many patients, PWS is caused by a mutation in a gene called RASA1. This mutation can run in families. A patient with PWS can pass this mutation on to his or her children. However, not every patient with PWS has a RASA1 mutation.

No known food, medication, or activity during pregnancy can cause PWS.

Doctors can sometimes see evidence of PWS in a prenatal ultrasound, and the capillary malformation is almost always apparent when your child is born.

If a child is older and you believe he has PWS, the first step to making a diagnosis is a complete medical history and a thorough physical exam. In many cases, that initial exam gives us enough information to diagnose PWS.

If there’s any doubt, your doctor may recommend one or more of the following imaging tests, which can help determine the correct diagnosis and the appropriate next steps in treatment:

• Magnetic resonance imaging (MRI): This high-resolution scan shows the extent of the hypertrophy (overgrowth) of tissue and gives your doctor information about what problems it may be causing.
• Ultrasound (also called ultrasonography): An ultrasound helps your doctor see your child’s vascular system to examine abnormalities and determine how much blood is flowing through the AVM.
• Computerized tomography scan (also called a CT or CAT scan): A CT scan shows detailed images of the area affected by PWS and is especially helpful for evaluating the bones in the affected limb.
• Angiogram: In this study, an interventional radiologist injects a dye into your child's blood vessels, giving doctors a detailed view of the blood vessels in the affected limb.
• Echocardiogram: An echocardiogram allows your child’s doctor to check the condition of her heart.

After we complete all necessary tests, our team of vascular anomalies specialists will review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best treatment options for your child.

Children with Parkes Weber syndrome (PWS) often need multidisciplinary care. Some specialists your doctor may recommend for your child include:

• Dermatologist
• Plastic surgeon
• General surgeon
• Interventional radiologist
• Orthopedist
• Hematologist

While there is no cure for PWS, the symptoms of the condition can be managed.

Depending on your child’s symptoms and the progression of the disease, we may also bring in:

• Physical therapists: PWS can affect your child’s arm or leg, making it hard or painful for your child to move it. A physical therapist can help ease the pain and increase your child’s range of movement.
• Occupational therapists: Children with PWS sometimes get behind on developing motor skills because of physical problems related to the disease. An occupational therapist can get your child back on track.
• Counselors: As your child gets older, he or she may be uncomfortable with the capillary malformation on his or her skin. One of our counselors can help your child deal with the psychological and social issues related to having a birthmark.

PWS is a progressive condition, which means that it will grow as your child grows. The long-term outlook depends on a few factors:

• The extent of the disease
• The amount of hypertrophy (overgrowth) in your child’s limb or limbs
• The condition of your child’s heart
• The abnormal blood vessels’ response to therapy
• The overall health of your child
• Your child's tolerance of specific medications, procedures, or therapies
• New developments in treatment

Depending on the severity of your child’s PWS, your doctor may recommend a series of follow-up visits to check for complications and make sure that we’re managing the PWS effectively.

Because PWS is so rare, very few doctors have experience diagnosing and treating it. The Vascular Anomalies Center at Boston Children's has evaluated more children with PWS than any other hospital in the world. The VAC's more than 25 physicians — representing over 16 medical and surgical specialties — draw on those experiences to continually refine the therapies and achieve better long-term outcomes for children with PWS.

The clinicians and scientists in the Vascular Anomalies Center strive to improve the care of patients with vascular anomalies like PWS by understanding the biology behind them.

Battling PWS at its source

PWS is caused by errors that occur when blood and lymphatic vessels are forming.

Our investigators are probing the genes and molecules that regulate the formation and growth of blood/lymphatic vessels. We hope that understanding the genes that control these molecular events will result in new therapies for vascular malformations.

The VAC conducts research that may lead to the development of new, more effective therapies and perhaps ultimately result in ways to prevent these anomalies. The VAC has generated an extensive case database on vascular anomalies, including many cases of PWS. Using this database, we are actively evaluating the best therapies for PWS and studying long-term outcomes after PWS. As our database grows, it helps to shine more light on this rare condition.

Surgical treatment

Traditionally, debulking — a surgical procedure where many of the abnormal vessels and some of the child’s overgrown tissue is removed — has not been a standard treatment for children with PWS. However, for more than 15 years, surgeons at Boston Children's Hospital have been performing large-scale debulking procedures to help children whose overgrown legs have left them wheelchair-bound.

We have developed a team approach to performing debulking procedures. The pre-surgical preparation and post-surgical care can be critical to the success of the surgery.