Cerebellopontine angle glioneuronal hamartoma.

Roughly 90% of cerebellopontine angle tumors are acoustic neuromas. Other prevalent lesions include meningiomas and epidermoid tumors; additional lesions are rare. We describe a patient with a neuroglial hamartomatous mass of the internal auditory canal who was thought to have a schwannoma preoperatively. In this case, the hamartomatous tissue containing neuroectodermal elements may have become separated from the developing neuraxis during neural migration. Hamartomas should be considered when masses are discovered originating from eighth nerve branches other than the superior vestibular nerve and when magnetic resonance signal characteristics vary from the T1 enhancement typically seen with schwannomas and meningiomas.