Most people are not aware of the medical condition Hemihyperplasia, also called Hemihypertrophy or Hemi, which is a greater-than-normal asymmetry between the right and left sides of the body. This difference can be in just one finger; just one limb; just the face; or entire half of the body, including half the brain, half the tongue and the internal organs, or any variation in between. The skin is often thicker, and there may be more hair on the head, on the larger side. Hemihyperplasia can occur as an independent condition (isolated Hemihyperplasia) or as a part of a genetic syndrome (i.e. Beckwith-Wiedemann syndrome). Isolated Hemihyperplasia is thought to occur in about 1 in 86,000 births. Some children with Hemihyperplasia also have a genetic syndrome, such as Beckwith-Wiedemann syndrome, Neurofibromatosis, Klippel-Trenaunay-Weber syndrome or Proteus syndrome. Although these occur in the minority of the children, each child with Hemihyperplasia should be evaluated by a geneticist to look for associated conditions. This is an overgrowth condition.
Hemihypoplasia is very similar to Hemihyperplasia as it still carries the traits of gretaer-than-normal asymmetry between the right and left side of the body, but it is an undergrowth condition. It can occur as part of a genetic syndrome know as Russell-Silver Syndrome.
Hemihyperplasia is a key warning to be on the lookout for several kinds of cancers. Because Hemihyperplasia a disorder of the body’s normal controls of growth, it is not surprising that people with this condition can also have a higher rate of cancer. In one study, 168 children with isolated Hemihyperplasis were very carefully followed to try to determine the true rate of cancer in children with this condition. Just under 6% developed childhood tumors (American Journal of Medical Genetics, 1998; 79:274–278). The most common cancer is Wilms’tumor (of the kidney), followed by adrenal carcinoma and liver cancer (hepatoblastoma).
Sadly, Hemihyperplasia often not looked for and not diagnosed until after the cancer has been discovered. Since children with this disorder are at an increased risk for certain types of abdominal cancers, they follow a strict screening protocol; every 6 weeks blood tests and every 3 months abdominal scans until the age of 7 (some believe in reducing blood draws once child reaches the age of 3). As children with Hemihyperplasia grow, the discrepancy between the two sides increases, but the relative proportions between the two sides usually remains the same over the long haul. Variations are found among different children, but in most children, the discrepancy about doubles between the first and fifth birthdays.
The next most immediate concerns are the orthopedic problems that result from any leg-length discrepancy. Over time, scoliosis, or curvature of the spine, commonly develops. This disappears when the leg lengths are equalized, either with surgery or with special shoes or lifts. Close contact with a skilled pediatric orthopedist is a must.
In adulthood asymmetry of the limbs can interfere with the proper function of their bodies, bones and joints and can cause pain. Insecurities due to disfigurement are possible and can be addressed through support groups or therapy. Adults with Hemihyperplasia often report back, hip and neck pain. Since adults with Hemihyperplasia have grown up with the condition, they usually know how to manage discomfort on their own.