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What is hemihyperplasia?

  • Hemihyperplasia is the enlargement of one part or side of the body causing asymmetry. This means one or more body part(s) are bigger when compared to the other side of the body. For example, one leg appears longer and thicker than the other leg, or one side of the body seems bigger than the other.
  • The enlargement is caused by overgrowth of bone or soft tissue.
  • Bone differences can be measured by x-ray. Enlargement of soft tissue can be hard to measure accurately.

What causes hemihyperplasia?

  • In most cases, hemihyperplasia is isolated, meaning it occurs without signs of other problems.
  • There is no single cause for hemihyperplasia, but there are genetic causes that can be signs of a medical condition. The cause varies and is looked at on an individual basis.
  • In some cases, hemihyperplasia can be a sign of a medical condition such as:
    • Beckwith-Wiedemann syndrome
    • Kippel-Trenaunay syndrome
    • Proteus syndrome
    • Neurofibromatosis Type I
    • Russel-Silver syndrome
    • Sotos syndrome

Why is hemihyperplasia a problem?

  • Overgrowth and asymmetry may lead to problems with the bones and joints.
  • Children with isolated hemihyperplasia or Beckwith-Wiedemann syndrome have a higher risk of getting certain types of cancer or kidney problems.
  • Other causes of hemihyperplasia may have other related medical problems.

How is this evaluated?

A genetic counselor and a genetics doctor or nurse practitioner will meet with you in the clinic. They will ask about your family’s medical history, examine your child and make recommendations. You will have time to ask questions.

Labs and/or radiology studies may be done.

What are the screening recommendations for isolated hemihyperplasia or Beckwith-Wiedemann syndrome?

  • A blood test called Alpha-Fetoprotein (AFP) tumor marker every 3 months until age 4.
  • An abdominal ultrasound every 3 months until age 8.
  • A kidney ultrasound every year from age 8 until mid-adolescence.

Although most people do not get tumors, screening tests are done to find tumors early when treatment is most effective and less invasive.

How is it treated?

  • There is no cure for hemihyperplasia and treatment depends on the cause of your child’s hemihyperplasia.
  • Your child may be recommended to see an orthopedics provider for treatment of abnormal limb size.


Children’s Hospital Specialty Center
Genetics and Genomics Program
2530 Chicago Avenue South
Minneapolis, MN 55404


This sheet is not specific to your child but provides general information.  If you have any questions, please ask the doctors or nurses. For more reading material about this and other health topics, please call or visit the Family Resource Center library.

Last reviewed 4/2016

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Minnesota Family Resource Center library, or visit

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