Glioma of the acoustic nerve.

We report a case of astrocytoma of the acoustic nerve. Most gliomas arise from the brainstem, and seldom originate in the acoustic or other "true" cranial and spinal nerves. Clinical features of this rare acoustic tumor differ from those of brainstem gliomas, but are indistinguishable from typical acoustic neurilemoma. We discuss the diagnosis and histogenesis of glioma arising in the eighth cranial nerve. Demonstration of glial fibrillary acid protein, an antigen specific for astrocytes, is a new method of verifying the diagnosis. Review of the literature indicates that a few cases of epithelial-like tumors of peripheral nerves may have been of neuroepithelial origin. The evidence, however, generally is not sufficient to exclude the possibility of metastatic neoplasms or other tumors such as malignant schwannoma and melanoma. Most of these putative gliomas contained gland-like tissue, and did not have the morphologic appearance of astrocytoma, as in approximately five reported examples, and in our case.