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Monday, 12 December 2005
Monday, 12 December 2005


Hemihypertrophy is the term for when one side or part of the body is larger than the other. It can occur by itself, or as part of another syndrome such as Beckwith-Wiedemann syndrome or neurofibromatosis. The differences in size can occasionally cause problems with posture or gait, for example if one leg is longer than the other. There may be other problems if the hemihypertrophy is part of a syndrome.


Hemihypertrophy that is not part of a syndrome is rare, between 1 in 14,000 and 1 in 86,000 births. When hemihypertrophy as part of other syndromes is included, it is slightly more common, but still very unusual. Children with certain syndromes are at risk for hemihypertrophy. These include Beckwith-Wiedemann syndrome, neurofibromatosis, Proteus syndrome, and Klippel-Trénaunay-Weber syndrome. Otherwise, there are not any identifiable risk factors for hemihypertrophy. There have been occasional reports of families with hemihypertrophy, but it does not generally run in families.

Signs and Symptoms

It may be apparent when one side or segment of the body is larger than other, but if the asymmetry is small, it may only be detected using X-rays or specific measurements. Hemihypertrophy can be present at birth or develop as the child grows. With small degrees of asymmetry, it may be difficult to distinguish hemihypertrophy from the normal variation that people have. Most people have minor asymmetries, such as one leg slightly longer than the other. These minor asymmetries are normal. Those who have hemihypertrophy as part of another syndrome will have the features that occur in the syndrome as well. In Beckwith-Wiedemann, they will have problems with blood sugar, and the internal organs will be larger than normal. In neurofibromatosis, there will be skin findings such as cafe-au-lait spots and small rubbery nodules in the skin. In Klippel-Trénaunay-Weber syndrome children also have abnormal clumps of blood vessels, called vascular malformations, in the skin and elsewhere. In Proteus syndrome, children have large hands and feet, and overgrowth of bones. If the degree of asymmetry is bad enough there may be some curvature of the spine (scoliosis), or trouble walking. This is strictly due to the asymmetry, and if it is corrected, the scoliosis or walking problems typically improve. The most significant concern with hemihypertrophy is that is has been associated with certain cancers that can occur in childhood, specifically cancers of the adrenal glands, liver and of the kidney (known as Wilms tumor). The association with cancer is only in children who have Beckwith-Wiedemann syndrome or hemihypertrophy without any other syndrome. The exact number is not well determined, but probably about 3% of these children will develop a cancer. Beckwith-Wiedemann syndrome increases this risk. Children with neurofibromatosis, Proteus syndrome or Klippel-Trénaunay-Weber syndrome are not at risk for these cancers.

Possible Causes

The cause of hemihypertrophy is not known, though some suggest it might be due to abnormal blood or lymph flow to the area. It has been associated with the syndromes as described above, but the specific reasons why one part of the body is larger are unknown, and may be different depending on whether there is a syndrome present or not.


The diagnosis of hemihypertrophy is by examining and measuring the child. X-rays may be taken to help measure how much asymmetry there is and to determine if there is scoliosis present or not. For those at risk for cancers, an ultrasound of the abdomen may be done to monitor for these cancers and try to identify them early.


If the asymmetry causes scoliosis or trouble walking, there are surgeries that can be done to make the leg lengths more equal to one another. Alternatively, an orthotic shoe or insert can be used to even out the legs. Reconstructive surgery can be done for significant asymmetry of the face or jaw. Most physicians do regular ultrasound examinations of the abdomen to monitor for cancers in those who are at risk. Regular ultrasounds will be done usually until the child is grown. How often these should be done is not known and should be decided for each child.


The hemihypertrophy specifically will not affect the length of the child’s life. If there is a cancer present, this will need to be treated, though survival for children with Wilms tumor is good. Scoliosis or walking problems are usually, though not always treatable. Children with other syndromes may have separate problems related to those syndromes that are not related to the hemihypertrophy.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.


Online information about hemihypertrophy is limited. The best parents resource is:

Hemihypertrophy Online Support and Information Group
This site is put together by a woman with the problem and provides some parent oriented information and links, as well as pictures.

Google Search for Hemihypertrophy

References and Sources

Ballock RT, Wiesner GL, Myers MT, Thompson GH. Hemihypertrophy. Concepts and controversies. J Bone Joint Surg Am. 1997;79:1731-8.