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What is hemihyperplasia?

Hemihyperplasia (sometimes referred to as hemihypertrophy) is a rare condition in which one side of the body or a part of one side of the body (such as a hand or leg) grows significantly more than the other due to an over-production of bone or soft tissue. This overgrowth causes visible unevenness or asymmetry.

Hemihyperplasia can also impact a child’s skin, muscle, fat, and bone cells, creating noticeable growth in the face, jaw, teeth, or other areas.

Hemihyperplasia | Symptoms & Causes

What are the signs and symptoms of hemihyperplasia?

Signs of hemihyperplasia can range from subtle to noticeable. This may mean asymmetry in a child’s face or a difference in size between one leg or arm and the other. In some cases, the asymmetry affects how a child walks (their gait).

Hemihyperplasia is often an isolated condition, which means it occurs without other problems, but children with hemihyperplasia also have an increased risk of benign (non-cancerous) or malignant (cancerous) tumors. Most commonly, these tumors are found in the kidneys.

What causes hemihyperplasia?

There is no single known cause of hemihyperplasia, but genetic factors can play a role. Hemihyperplasia is a congenital overgrowth disorder, meaning a child is born with it.

In some cases, hemihyperplasia can signal a medical condition such as Beckwith-Wiedemann syndrome, which is a genetic overgrowth disorder that can cause physical malformations and tumors.

Hemihyperplasia | Diagnosis & Treatments

How is hemihyperplasia diagnosed?

To diagnose hemihyperplasia, your child’s doctor will do a physical exam and ask about their medical history.

Your child’s doctor may also order tests such as:

  • MRI
  • x-ray
  • CT scan
  • genetic testing to determine if the hemihyperplasia is isolated or is a sign of another syndrome such as Beckwith-Wiedemann syndrome.

How is hemihyperplasia treated?

There is no cure for hemihyperplasia, but at Boston Children’s, your child will receive treatments specific to their symptoms. This may include:

Our approach to hemihyperplasia

Boston Children’s Hospital has specialists who treat the concerns associated with hemihyperplasia. Your child will be seen by the experts in our Craniofacial Program, which is one of the nation’s leading programs for children with abnormalities of the face and skull. Our Vascular Anomalies Center also provides expert treatment of craniofacial anomalies.

Hemihyperplasia | Programs & Services