Congenital intracerebral epithelial cysts.

The problem of intracerebral congenital epithelial cysts is discussed with reference to five clinical cases. On the basis of their morphological structure the author differentiates the intracerebral cyst with a ciliated, columnar epithelium from the ependymal cyst proper (more frequently located in the lateral recess of the medulla oblongata) and the posterior cerebellar cyst of meningeal arachnoid origin. The cyst with a ciliated columnar epithelium appears to be an ectopic intracerebral tissue, whose neuroepithelial or endodermic origin still remains to be demonstrated. This cyst has been commonly described as a colloid (epithelial) cyst of the 3rd ventricle but may also be localized at other points in the central nervous system. One of the cases studied was an epithelial cyst in the frontal lobe, without any connexion with the ventricle, and evolving as a cerebral tumour.