Cerebellopontine Angle Tumor Composed of Schwann and Meningeal Proliferations

Abstract

Tumors found in the cerebellopontine angle are predominantly vestibular schwannomas. Mixed tumors found within the cerebellopontine angle are thought to be exceedingly rare and exclusively associated with neurofibromatosis 2. We report a case of a mixed tumor composed of Schwann and meningeal cell proliferations in a patient who was not diagnosed as having neurofibromatosis 2. Mixed tumors composed of neoplastic Schwann and meningeal cells have rarely been reported. However, new evidence indicates that these mixed tumors may be more common than was previously thought and may have an interrelated mechanism of pathogenesis. Although the case we describe does not fulfill the current diagnostic criteria for neurofibromatosis 2, a presumptive diagnosis was given, suggesting that the current diagnostic criteria for neurofibromatosis 2 may be too narrow.

Islets of meningioma in an acoustic schwannoma in a patient with neurofibromatosis-2: pathology and magnetic resonance imaging findings

“…As reported by ELİSABETH et al, the English literature up to 2001 reveals 9 cases of mixed tumors, including their own case (4). We found three additional case reports (2,7,8). In all these cases, including ours, the mixed tumors were composed predominantly of schwannomas, with lobules of meningotheliomatous cells presenting as micromeningiomas.…”

A Rare Case of Radiologically Not Distinguishable Coexistent Meningioma and Vestibular Schwannoma in the Cerebellopontine Angle – Case Report and Literature Review

“…They represent approximately 10% of all intracranial tumors and more than 80% of CPA tumors [3, 4]. Meningiomas arise from the dural coverings of the brain and are the most common benign intracranial tumors, accounting for 13–26% of all primary intracranial tumors [8].…”

“…NF-2 is an autosomal dominant inherited disease with an incidence of less than 1 in 25,000 people [11]. The diagnosis of NF-2 is made clinically, and the current diagnostic criteria for NF-2 are met when an individual has either characteristic bilateral VSs or a first-degree relative with NF-2 and one of the following: a unilateral VS before the age of 30 years or the presence of 2 tumors (neurofibroma, meningioma, glioma, schwannoma, or juvenile posterior subcapsular lenticular opacity) [3, 12]. Furthermore, the pathogenetic mutation in the NF-2 gene on chromosome 22 can be identified by genetic testing [13].…”

“…In contrast, unilateral VSs infrequently display a lobular pattern, normally have lower cellularity and abnormal vasculature, and are not associated with meningiomas [3]. …”

“…In the cerebellopontine angle (CPA) these tumors comprise 6–15% [1, 2] and 80% [1, 3, 4], respectively, of all tumors. While the occurrence of these brain tumors in one patient is well known in phakomatoses, as for example in neurofibromatosis type 2 (NF-2), or with a history of previous irradiation of the brain [5, 6], it is a very rare condition without these circumstances.…”