Hamartomas and choristomas in the nervous system.

Hamartomas are an overgrowth of mature tissues that normally occur in an area of the body, but with disorganization and often with one element predominating. Choristomas on the other hand, are a mass of tissue histologically normal for a part of the body other than the one in which it is located (heterotopic/ectopic). Many reports use choristoma and heterotopia interchangeably. What is included in the definition of hamartoma or choristoma varies. Malformations may be sometimes considered to be hamartomas and many ectopias could be included in the definition of choristoma. Hamartomas and choristomas can occur anywhere in the body including the nervous system.