Unusual large cystic acoustic neurinomas: report of two cases.

Two rare cases of large cystic acoustic neurinomas are reported in this paper. Such cases are sometimes misdiagnosed preoperatively because their computed tomography appearances resemble those of other cystic lesions in the cerebellopontine angle. The diagnosis of acoustic neurinoma should be kept in mind if one finds a large cystic cerebellopontine angle tumor, even if there are no typical clinical symptoms or erosion of the internal auditory canal. Magnetic resonance imaging of large cystic acoustic neurinomas are also described in this paper.