[A case of choroid plexus papilloma at the right cerebello-pontine angle (author's transl)].

A rare case of the choroid plexus papilloma originating from the extraventricle was reported. A 48-hear-old woman began not to walk well about two years ago. Then, she was complained of vertigo, hearing disturbance of the right ear and nausea. These symptoms gradually increased. On admission she had papilledema, Brun's nystagmus, hearing disturbance of right ear and cerebellar ataxia. Cerebral angiogram and CT scan showed dilated ventricles and a large tumor in the posterior fossa. At operation, tumor was found in extramedullary space at the right cerebello-pontine angle and extended to the foramen magnum. This was removed totally. Histological examination revealed choroid plexus papilloma. Her postoperative course was satisfactory and shunting procedure was not necessary. According to the electron microscopic findings, the ultrastructure of tumor was similar to that of normal choroid plexus. We could not clear the morphological features which were considered essential for overproduction of CSF in the tumor.