Ancient Schwannoma affecting the intracranial portion of the trigeminal nerve: A case report

Clinical and radiological features of intracranial ancient schwannomas: a single-institution, retrospective analysis

Ancient schwannoma (AS) is a subtype of schwannoma characterized by slow progression despite degenerative changes in pathology. Although it is considered a benign tumor, most previous reports have focused on extracranial AS; therefore, the clinical characteristics of intracranial AS is not clear. We included 174 patients who underwent surgery for sporadic intracranial schwannoma, and 13 patients (7.5%) were diagnosed with AS. Cysts were significantly more common in patients with AS than conventional schwannomas (92.3% vs. 44.7%, p < 0.001), as was bleeding (38.5% vs. 6.9%, p = 0.003) and calcification (15.4% vs. 1.3%, p = 0.029). The maximum tumor diameter was also larger in patients with AS (35 mm vs. 29 mm, p = 0.017). The median duration from symptom onset to surgery (7.0 vs. 12.5 months, p = 0.740) did not significantly differ between groups, nor did the probability of postoperative recurrence (p = 0.949). Intracranial AS was strongly associated with cyst formation and exhibited a benign clinical course with a lower rate of recurrence and need for salvage treatment. Extracranial AS is reportedly characterized by a slow progression through a long-term clinical course, whereas intracranial AS did not progress slowly in our study and exhibited different clinical features to those reported for extracranial AS.

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.