The imaging of body asymmetry and hemihypertrophy.

Localized soft tissue and bone overgrowth may be the result of many different causes and will vary in severity, from involvement of a single digit to one half of the body. There are a variety of causes, including chronic lymphedema; lymphangiomatous malformations; neurofibromatosis; vascular malformations including the Klippel-Trenaunay-Weber syndrome; macrodystrophia lipomatosa; multiple enchondromatosis and Maffucci's syndrome. More recently, the Bannayan syndrome and the Proteus syndrome have been documented among the causes. Unexplained hemihypertrophy may also occur in association with intra-abdominal neoplasms. The various entities are reviewed and their radiological features described and illustrated.