Intracranial ancient schwannoma originating from vestibular nerve: A case report and review of the literature.

Background: Ancient schwannoma (AS) is a subtype of schwannoma with degenerative features, which often progresses slowly over a long period of time. Intracranial AS is a rare benign tumor and there are no detailed reports of AS originating from the vestibular nerve. Case Description: Herein, we present the case of a patient with the right vestibular schwannoma with multiple meningiomas and review three previous cases of intracranial AS. Near-total resection was performed for vestibular schwannoma and the pathological findings were AS (World Health Organization Grade I). Five months postoperatively, gamma knife radiosurgery was performed for a recurrent lesion of the right vestibular schwannoma in the internal auditory meatus. Although AS is known to be a benign pathology, there are cases of rapid growth and early recurrence, as the one presented here. The high Ki-67 index (up to 5%) and the presence of cysts may be related to the rapid progression of intracranial AS. Conclusion: Therefore, careful follow-up is necessary even if adequate removal is achieved. In addition to pathological studies, the genetic background of intracranial AS warrants future investigations. Further accumulation of cases is necessary to clarify the clinical features of intracranial AS.