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).
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.
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.
Hemihyperplasia is rare. Research shows that Beckwith-Wiedemann syndrome, the most common subtype of hemihyperplasia, happens in about 1 in every 11,000 births.
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:
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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:
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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:
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.
Last reviewed by a Cleveland Clinic medical professional on 09/06/2022.
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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