Hemihypertrophy: Definition, Prevalence, Causes, Symptoms, Diagnosis and Treatment

It is a rare disorder in which one side of the body grows significantly due to excess cell production, causing asymmetry.

Hemihypertrophy is better known today as hyperplasia.

In a normal cell, there is a mechanism that stunts growth once the cell reaches a specific size. However, in hemihyperplasia, cells on one side cannot stop growing.

This causes the affected area of ​​the body to grow or become abnormally large.

The disorder is congenital, which is evident from the child’s birth.

Causas de la hemihipertrofia

No one is exactly sure what causes hemihyperplasia, but there is some evidence that the disorder runs in families.

Genetics seem to play a role, but the genes that seem to cause hemihyperplasia can differ from person to person.


A mutation on chromosome 11 is suspected of being associated with hemihyperplasia.


Statistics vary depending on the number of people with this disorder. There are many reasons for this. First of all, the symptoms of hemihyperplasia are similar to other diseases, so sometimes, the diagnosis can be confused with others.

Also, sometimes the asymmetry or overgrowth on one side can be so slight that it is not easily recognizable.

What are the symptoms of hemihypertrophy?

The most apparent symptom of hemihyperplasia is the tendency of one side of the body to be larger than the other side. An arm or leg can be longer or more prominent in circumference. The trunk or face on one side is more significant in some cases.

Sometimes this is not noticeable unless the individual lies on a flatbed or surface (called the bed test). The difference in posture and gait (how someone walks) is apparent in other cases.

Children with hemihyperplasia are at increased risk of developing tumors, specifically in the abdomen. Tumors are abnormal growths that can be benign (not cancer) or malignant (cancer).

In hemihyperplasia, the cells that form a tumor have often lost the ability to stop or “turn off” the growth mechanism. Wilms tumor, cancer that occurs in the kidneys, is the most common.

Other types of cancerous tumors that are associated with hemihyperplasia are hepatoblastomas (of the liver), adrenocortical carcinomas (of the adrenal gland), and leiomyosarcomas (of the muscle).

How is it diagnosed?

A diagnosis is usually made through a physical exam. Symptoms are associated with other conditions, such as Beckwith-Wiedemann syndrome (BWS), Proteus syndrome, Russell-Silver syndrome, and Sotos syndrome.

Before diagnosing, your healthcare provider should rule this out. They may also order diagnostic images to detect tumors.

Because this disorder is rare and often overlooked, it is recommended that the diagnosis be made by a clinical geneticist who is familiar with it.


If you think your child has hemihyperplasia or has been diagnosed, consider the following:

  • Obtain a referral to a clinical geneticist for evaluation.
  • Know your doctor’s plan for tumor surveillance. Some guidelines recommend screening for tumors during the first six years. Others recommend abdominal ultrasounds every three months until the age of 7 years.
  • Ask your doctor if you should take a serum alpha-fetoprotein (SAF) measurement. Some guidelines recommend that the SAF level be measured every three months up to 4 years. In some cases, SAF, a type of protein, is very high in babies with hemihyperplasia.

If your child is diagnosed with hemihyperplasia, it is good to perform an abdominal exam of your child regularly. Ask your doctor for recommendations on how to do this. Parental involvement in treatment has proven effective in some cases.

How is hemihypertrophy treated?

There is no cure for hemihyperplasia. Treatment focuses on detecting tumor growth and treating tumors.

For abnormal limb size, orthopedic treatments and corrective shoes may be recommended.