Primary CNS tumors presenting as cerebellopontine angle tumors.

Adult patients with posterior fossa tumors arising from the cerebellum and brainstem are reported. In each case the tumor presented as a cerebellopontine angle tumor and not as an intra-axial tumor. Tumors of CNS origin are uncommon in the posterior fossa in adults, but they may be seen by the otologist if the presenting symptoms are audiologic or vestibular. Computed tomography scanning will not always distinguish these lesions from the much more common extraaxial neurinoma, meningioma, or cholesteatoma. The progression of symptoms is more rapid in these patients, and other associated neurologic deficits are more common. The auditory brainstem response may demonstrate characteristic abnormalities in these patients. The differential diagnosis of these tumors in adults is discussed and the recent literature reviewed.