Large ependymal cyst of the cerebello-pontine angle in a child.

Most ependymal cysts occur intracerebrally, with a few cases situated in the subarachnoid space. The cerebellopontine angle is a common site for arachnoid cysts, but a very rare site for ependymal cysts. A case is described here of a large ependymal cyst in the cerebellopontine angle. A 12-year-old girl with left hearing disturbance was admitted. CT and MRI revealed a cystic tumor in the left cerebellopontine angle. At operation, we obtained a discrete thin-walled cyst which had arisen from a continuation of the choroid plexus of the lateral foramen of Luschka, which had no connection with the arachnoid. The cyst proved to be an ependymal cyst.