[MIM 235 000]

(body hemihyperplasia, Hemi-3)

Very rare: incidence estimated at 1/86,000 live births. Mutation in the  LIT1 and/or H19 genes on 11p15. Enlargement of half or any part of the body following a regional increase of cell proliferation. The degree of asymmetry is variable. There are:

-          partial or simple hemihypertrophy, which only implies a limb or part of this limb (extreme form: megalodactyly)

-         complex hemihypertrophy: concerns a whole hemibody

-         crossed hemihypertrophy: that affects both sides of the body.

Hemihypertophy can be isolated or part of a syndrome such as Beckwith-Wiedemann, Proteus or Klippel-Trenaunay-Weber syndrome, or even in some cases of neurofibromatosis type I (see these terms).

Whole body hemihypertophy is strongly associated with an increased risk of cancer of embryonic origin, in particular nephroblastoma (Wilms Tumor) and hepatoblastoma, especially in case of parental disomy on 11p15. Rare cases of adrenal tumors have also been reported. This is why it is recommended to perform an abdominal ultrasound every 3 months up to 6 years of age and every 6 months until puberty.

The hemi 3 syndrome combines body hemihypertrophy, hemihypoesthesia and hemireflexia as well as scoliosis. In the reported cases, the hemihypertrophy was located on the right side. There is in general a notion of neural tube defect in the family (spina bifida).

Anesthetic implications: 

difficult venous access on the hypertophic side; possible problems linked to the associated tumoral pathology.

References : 

Updated: April 2019