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What is a venous malformation?

A venous malformation (VM) is a bluish lesion caused by widened, abnormally shaped veins. While rare, VMs are the most common kind of vascular malformation treated at the Boston Children's Hospital's Vascular Anomalies Center.

The blood vessel walls in a venous malformation are unusually thin and have relatively little smooth muscle around them, allowing them to stretch abnormally. A VM can be large or small and can enlarge as a child grows older.

Children can have multiple VMs and may experience a wide range of symptoms based on where the malformation occurs and its size. A child may have just an isolated VM or have them as part of an underlying condition. VMs do not go away on their own and often recur after treatment.

Are there different types of venous malformations?

There are also rare sub-types of venous malformations, which make up approximately 10 percent of all VMs such as:

  • Glomuvenous malformation (GVM): Glomus cells are smooth muscle cells that are believed to regulate blood flow. Glomus cells in GVMs are shaped abnormally.
  • Cerebral-cavernous malformation (CCM): CCM is a familial disorder characterized by the formation of multiple VMs in the brain. These lesions often bleed and expand. About 10 percent of kids with this disorder develop skin VMs.
  • Blue rubber bleb nevus syndrome (BRBNS): Children with BRBNS typically have multiple VMs of the skin and internal organs.
  • Maffucci syndrome: Children with this condition have multiple benign bone tumors (enchondromas) and VM-like lesions of the skin.

What are the symptoms of venous malformations?

Venous malformations (VMs) most commonly appear on the skin but can be present in other tissues and organs as well. They are typically blue, soft, and compressible.

They can range in size from a very small lesion in one spot to widespread lesions that also affect the underlying tissue, muscles, and bones. They can also arise on their own or as part of an underlying condition like blue rubber bleb nevus syndrome.

VMs can appear anytime during childhood, adolescence, or adulthood. Most are present at birth, though they may not be apparent or diagnosed until later — especially if the malformation is small or not in an obvious location.

The symptoms of a VM depend on the malformation's size and location and most commonly include:

  • pain
  • swelling
  • psychological/social issues related to the appearance of the lesion

What causes venous malformations?

VMs are caused by genetic mutations that arise during the embryonic stage of life. No known food, medication, or activity during pregnancy can cause a VM.

What are the most common venous malformation complications?

Some possible complications include:

  • pain when the VM suddenly expands if a clot forms
  • growth as the result of injury or during puberty
  • obstruction of vital functions like breathing or vision
  • fractures of the affected bone, and arthritis with limbs impacted by VMs
  • a pulmonary embolism if a large VM affects a child’s deep venous system
  • chronic bleeding and anemia with gastrointestinal VMs

How we care for venous malformations

The Vascular Anomalies Center at Boston Children's takes an interdisciplinary approach to care of children with venous malformations, whether the child is initially reviewed at our conference or seen in clinic. On your first visit to clinic, several VAC specialists will often review your child's case at the same time. Our experience in treating over 2,000 patients with venous malformations gives us the depth of knowledge to ensure you have an accurate diagnosis.

Venous Malformation | Diagnosis & Treatments

How is a venous malformation diagnosed?

In many cases, a complete medical history and a thorough physical exam provide enough information to diagnose a venous malformation (VM).

What tests may my child need?

In some cases, your doctor may recommend one or more of the following imaging tests to help determine the correct diagnosis and the appropriate next steps in treatment:

  • Ultrasound (also called ultrasonography): An ultrasound helps your doctor see your child’s venous system to examine abnormalities.
  • Magnetic resonance imaging (MRI): This high-resolution scan can confirm the diagnosis, and allow your doctor to determine the size of the malformation and plan the next steps in treatment.
  • Computerized tomography scan (also called a CT or CAT scan): Your doctor may recommend a CT scan to examine a VM that’s affecting your child’s bones.

After all necessary tests are completed, the care team will review and discuss your child's condition then meet with you and your family to outline the best treatment options.

We advise consulting a vascular anomalies specialist if:

  • A VM is in a critical location, such as around her eye, face, or neck.
  • A VM involves the hands, feet, or an internal organ, such as the gastrointestinal tract, liver, or brain.

What are the treatment options for a venous malformation?

Because there’s no cure for a venous malformation (VM), we focus on managing your child’s symptoms. We only recommend treating a VM if the malformation:

  • causes pain
  • creates a deformity
  • obstructs a vital structure such as your child's airway
  • affects your child's vision
  • causes gastrointestinal bleeding

Children with VMs sometimes need multidisciplinary care. Specialists that may be part of your child’s care team include the following:

  • dermatologist
  • plastic surgeon
  • general surgeon
  • interventional radiologist
  • orthopedist
  • hematologist

The treatment options we recommend may include:


Sclerotherapy, in which an interventional radiologists injects a solution into the malformation that irritates the abnormal veins and makes them shrink or disappear, is our first choice of therapy.

Compression garments

If your child has a VM on his arm or leg, your doctor may recommend that he or she wear these tight-fitting pieces of clothing on the affected limb to reduce pain and swelling.

Anticoagulant therapy

One of the potential risks of a large VM is that a blood clot formed in the abnormal blood vessels will cause pain. Your doctor may recommend that your child take a daily dose of an anticoagulant (blood-thinning) medication to help prevent clots from forming. Venous malformations can also have problems with coagulation proteins that are consumed in the abnormal vessels and make a patient prone to bleeding as well as clotting, so the use of anticoagulant therapy should be monitored by your doctor.

Sirolimus therapy

Medical treatment with sirolimus can decrease pain and the fullness of venous malformations and improve coagulation levels.

Surgical resection

Surgical resection is a procedure where a surgeon removes part or all of your child's lesion. We may recommend resection if:

  • A child has a small lesion that can easily be removed completely.
  • Your child has GVMs (which are small and typically don't respond well to sclerotherapy) or gastrointestinal VMs.
  • Your child has a deformity after undergoing sclerotherapy.

What is the long-term outlook for children with venous malformations?

A VM is a chronic condition, which means that it will stay with your child as he grows. That said, many kids — especially those with mild VMs — live normal, healthy lives.

VMs can expand after treatment, even with surgery or sclerotherapy. For this reason, a child with a VM may undergo multiple treatments. Depending on the severity of your child’s condition, your doctor may recommend a series of follow-up visits to check for complications and make sure that we’re managing your child’s VM effectively.

Venous Malformation | Research & Clinical Trials

Boston Children's Hospital is a world leader in opening new avenues of "translational research," bringing laboratory advances to the bedside and doctor's office as quickly as possible. Our Vascular Anomalies Center (VAC) conducts research that may lead to the development of new, more effective therapies and perhaps ultimately result in ways to prevent these anomalies.

Battling venous malformations at their source

A venous malformation (VM) is caused by errors that occur when blood vessels are forming, and our investigators are currently probing the genes and molecules that regulate the formation and growth of blood vessels. Understanding the genes that control these molecular events will hopefully result in new therapies for vascular malformations.

New treatment for venous malformations?

VMs can sometimes grow, requiring aggressive treatment to protect your child's health. Research at Boston Children's has shown that urine testing can help monitor VMs and predict those about to become a serious threat.

These findings suggest that angiogenesis (the formation of new blood vessels) plays a role in the progression of vascular malformations, raising the possibility of curbing these difficult-to-treat anomalies with anti-angiogenic drugs.

We’re currently studying why VMs enlarge or return after treatment. Currently no medication is available to treat venous malformations, but our goal is to develop drug treatments for kids with these lesions. Each time we operate on a VM, we investigate a portion of the lesion to learn how the blood vessels enlarge.

Venous Malformation | Programs & Services