Meningeal Cysts

Abstract

Cystic lesions filled with clear fluid and located within the arachnoid membrane may be classified in terms of their localization along the neuraxis, or in terms of the structure of the cyst wall which may consist of either arachnoid connective tissue or of glio-ependymal tissue. There is overlap for these classifications, as arachnoid and glio-ependymal cysts may occur in the same locations, though not with the same frequency at any given location. Further, some cysts may combine features of arachnoid and glio-ependymal cysts, or light microscopic identification of the elements forming the cyst wall may be doubtful. Some cysts, for example, are lined with flattened or cuboidal, nonciliated cells whose derivation from ependyma or from metaplastic arachnoid tissue is a matter of conjecture. Some of the cysts described in the present chapter also resemble other types of cysts, such as neurenteric cysts (Chapter 26), or colloid cysts. The following text refers to the general histologic features of arachnoid and glio-ependymal cysts first, followed by a review of their occurrence at typical sites along the neuraxis.KeywordsCyst WallArachnoid CystArachnoid MembraneColloid CystNeurenteric CystThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.