Neuroepithelial cysts of the posterior fossa: pathogenesis and report of two cases.

We present two cases of simple neuroepithelial cyst--one at the cerebellopontine angle and the other in the pontine brain stem--in which a basement membrane was detected. The pathogenesis of these cysts, their diagnosis using computed tomography-metrizamide cisternography and nuclear magnetic resonance imaging, and their surgical treatment by fenestration and drainage are discussed.