Epithelial cysts of the neuraxis: presentation of three cases and a review of the origins and classification.

Benign, epithelial-lined cysts of the neuraxis may be asymptomatic or may behave as space-occupying lesions. Presentation of three such cysts, including an intramedullary epidermoid cyst, a lumbosacral subcutaneous enteric cyst that has an epithelium resembling ependyma, and a hypophyseal duct cyst, illustrates typical problems encountered. Review of their histogenesis and possible embryogenesis indicates that intracranial ependymal cysts and cysts of the sella turcica are not normally associated with other anomalies and frequently occur after middle age, whereas dermal and enteric cysts occur within the first two decades and are commonly associated with vertebral anomalies and other dysraphic syndromes. Enteric cysts may have a variable histologic appearance, including one resembling ependymal cysts. Recognition of the latter is important because of a possible associated dysraphic syndrome and the presence of an extraneuraxial component with the former but not the latter.