Hemihyperplasia, also known as hemihypertrophy, is asymmetry in size between the right and left of the body, more than can be attributed to normal variation.
Hemihyperplasia is more scientifically correct than hemihypertrophy as the cells are hyperplastic rather than hypertrophied .
Incidence is estimated at 1 in ~50,000 live births .
Hemihyperplasia can arise sporadically as isolated hemihyperplasia, or it can arise as part of a syndrome :
- Beckwith-Wiedemann syndrome
- Proteus syndrome
- Klippel-Trénaunay syndrome
- neurofibromatosis type 1
- Hemihyperplasia-multiple lipomatosis (HHML)
- McCune Albright Syndrome
- Langer Giedeon Syndrome
Increased risk (5% of patients) of malignancy, most commonly Wilms tumors .