Prepontine epithelium-lined cyst

Abstract

A 30-yr-old woman presented with recurrent episodes of severe headache associated with visual disturbances. Neurological examination showed minimal neurological deficits. Angiography, computerized tomography and radioisotope cisternography revealed a large cyst in the prepontine region, which did not communicate with either the subarachnoid space or the ventricular system. Histologically the cyst was lined by columnar and/or cuboidal cells, which contained materials positive on periodic acid-Schiff staining. Ultrastructurally there were 2 types of cells, ciliated and nonciliated. Characteristic findings were continuous basement membrane, microvilli covered with electron-dense material, several intercellular junctional devices and an open intercellular space which was occasionally filled with a migrating cell. The epithelial cyst with such features was apparently derived from endodermal tissue rather than from neuroepithelium. EM examination is indispensable in making a correct diagnosis of intracranial cysts.