If one side of your child’s body is growing more than the other side, it could be hemihyperplasia, also known as hemihypertrophy or overgrowth syndrome. This rare, congenital condition increases the risk of Wilms tumor (a type of kidney cancer) and hepatoblastoma (pediatric liver cancer).


What is hemihyperplasia?

Hemihyperplasia (heh-mee-hyper-play-zuh) is when one side of the body grows more than the other side. It’s also called overgrowth syndrome or hemihypertrophy. It usually affects the face, arms or legs. It can also affect the internal organs, especially in the abdomen (belly). Size variations between the two sides of the body are usually subtle at first, then become more obvious with growth.

Who does hemihyperplasia affect?

Hemihyperplasia affects children, both boys and girls. It’s a congenital condition, meaning it’s present at birth. Sometimes it’s diagnosed at birth. Other times, it’s not diagnosed until the child grows, and size differences become more apparent.

How common is hemihyperplasia?

Hemihyperplasia is rare. Research shows that Beckwith-Wiedemann syndrome, the most common subtype of hemihyperplasia, happens in about 1 in every 11,000 births.

How does hemihyperplasia affect my child?

The most obvious way hemihyperplasia affects your child is size differences between two body parts that are usually symmetrical. For example, one side of the face may appear larger (and more grown) than the other side.

Having hemihyperplasia increases cancer risk, specifically Wilms tumor (a type of kidney cancer) and hepatoblastoma (pediatric liver cancer). This is because of the way the growth differences affect your child’s organs.

If your child has hemihyperplasia, they will most likely need regular cancer screenings until at least age 7, including:


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Symptoms and Causes

What are hemihyperplasia symptoms?

The most prominent symptom of hemihyperplasia is when one side of the body grows larger than the other. Sometimes the difference is subtle but becomes more obvious over time.

Other symptoms (which are features of Beckwith-Wiedemann syndrome) include:

What’s the difference between hemihyperplasia and hemiatrophy?

Both conditions cause size differences in the body. Hemiatrophy refers to underdevelopment of one side of your body. Hemiatrophy usually only affects one area of the body, such as the arms. Hemihyperplasia affects multiple areas at the same time.

What causes hemihyperplasia?

In some cases, the genetic syndrome called Beckwith-Wiedemann syndrome causes hemihyperplasia. Other times, the condition isn’t associated with any genetic disorders, and providers don’t know the cause. When it’s not linked to a chromosome abnormality, the cause is sporadic and happens by chance.


Diagnosis and Tests

How is hemihyperplasia diagnosed?

There is no specific test for diagnosing hemihyperplasia. If your child’s provider sees uneven growth between two areas of the body, they will perform a physical evaluation and genetic testing to check for Beckwith-Wiedemann syndrome. Genetic testing helps your provider determine if a genetic syndrome is the cause.

Your child’s provider may also perform ultrasounds to examine the internal organs for uneven growth or tumors.

Management and Treatment

Is there a cure for hemihyperplasia?

No, there is no cure for hemihyperplasia. Your child’s care team will develop a treatment plan that meets their needs and targets their symptoms.


What’s involved in hemihyperplasia treatment?

Your child’s hemihyperplasia treatment depends on how extensive the difference is between the two sides of the body. Your child’s care team may include:

These specialists work together to develop your child’s treatment plan and monitor their abdominal organs. Your child’s providers also monitor for conditions like hepatoblastoma since hemihyperplasia increases cancer risk.

Will my child need surgery for hemihyperplasia?

Sometimes surgery can correct limb differences. There are different types of surgery for this. If your healthcare team recommends surgery, talk to them about which type is right for your child. Your child may have a procedure to:

  • Lengthen the shorter limb.
  • Help slow down the growth of the larger limb.

Are there complications or side effects of treatment for hemihyperplasia?

If your child has surgery, they may feel tired for a few weeks as they recover. They might also have pain at the incision sites. Ask your provider about other possible side effects of your child’s specific procedure.

How long does it take to recover from surgery for hemihyperplasia?

Recovery time varies depending on your child’s surgery. Your child may have some swelling, pain or numbness for days or weeks following the procedure. Talk to your child’s provider if healing doesn’t improve over time.


How can I prevent hemihyperplasia?

You can’t prevent hemihyperplasia that happens by chance during pregnancy. If your child has hemihyperplasia caused by Beckwith-Wiedemann syndrome and you wish to add to your family, talk to your provider about genetic testing. This type of testing can help ensure you don’t pass the chromosomal abnormalities to your future children.

If you or your partner has a history of genetic disorders and you are considering getting pregnant, talk to your healthcare provider. You may want to consider preconception counseling.

Outlook / Prognosis

What can I expect if I have hemihyperplasia?

If you or your child has hemihyperplasia, you may experience difficulties related to the uneven sizes between body parts. For example, it may be harder to find clothes that fit. Limb length differences can sometimes affect physical abilities like crawling, walking and running.

A hemihyperplasia diagnosis also means your child will have regular screenings for cancer. You can expect your child to have screenings every few months until age 7.

What is the outlook for hemihyperplasia?

Hemihyperplasia is a lifelong condition. Studies show that early diagnosis and regular screening for tumors provide a better outlook. If a child who has regular screenings develops cancer, it’s more likely to be a smaller tumor and early-stage disease. Treatment is typically more successful when started in the early stages.

What is the average hemihyperplasia life expectancy?

Most children with hemihyperplasia live healthy lives and have a typical life expectancy. While screening for cancer is important during childhood, the increased risk goes down as the child grows into an adolescent.

Living With

What questions should I ask a provider about hemihyperplasia?

If your child has hemihyperplasia, you likely have questions. Get the answers to set your mind at ease and prepare for the road ahead. Ask your child’s healthcare provider:

  • Is my child’s case of hemihyperplasia genetic or sporadic?
  • Why are you recommending this treatment or procedure?
  • What can I do to make my child more comfortable before and after surgery?
  • How long will my child need to stay in the hospital?
  • What type of incision will there be, if any?
  • What medications will my child need, if any?
  • What are the risks of my child’s surgery and anesthesia?
  • How long will it take for my child to recover after surgery?
  • What can I expect for my child’s long-term health?

A note from Cleveland Clinic

Hemihyperplasia, also known as hemihypertrophy or overgrowth syndrome, is a congenital condition that causes one side of the body to grow more than the other side. These growth differences might not be obvious at birth. If you notice limb length or body size disparities in your child as they grow, talk to a pediatrician. Since this condition increases cancer risk, getting an early diagnosis is important.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 09/06/2022.

Learn more about our editorial process.

Call Appointment Center 24/7 866.320.4573
Questions 216.444.2200