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

Abstract

Mixed tumors of the cerebellopontine angle, composed of meningioma and schwannoma components, are extremely rare; so far, only 12 cases have been reported in the literature. They are thought to be exclusively associated with neurofibromatosis-2. We present a mixed tumor of schwannoma and meningioma in a patient with neurofibromatosis-2 and discuss the pathology and magnetic resonance imaging (MRI) findings in relation to the literature. Review of the literature shows that a typical MRI pattern has not been established for mixed tumors and it seems unlikely that a meningioma component can be differentiated within a schwannoma preoperatively.

Cases of Mixed Schwannoma–Meningioma With and Without Neurofibromatosis 2 with Emphasis on Tumorigenesis

“…The metaplasia hypothesis proposes metaplasia of cell lines with meningoepithelial cell pockets, which later proliferate, giving rise to tumors. 5 The stimulus hypothesis suggests that schwannoma may act as a stimulus, causing a meningothelial reaction and giving rise to meningioma. Pallini et al 6 reported a synergistic effect of one tumor over the development and growth of another through an autocrine or paracrine growth-stimulatory mechanism that involved an epidermal growth factor (EGF)-like factor.…”

Triad of Intraspinal Meningioma, Schwannoma, and Ependymoma

“…13,14 Since their occurrence was first described by Cushing and Eisenhart 15 in 1938, just over a dozen case reports of mixed schwannomas and meningiomas (both components seen together in the same tumor) arising in patients with NF-2 have been published. [1][2][3][4] Even more rarely, with just 3 case reports to our knowledge, mixed schwannomas and meningiomas have been reported in patients without definite clinical evidence of NF-2. [6][7][8] In all 3 cases, the mixed tumor was located in the cerebellopontine angle.…”

“…There are only a few single case reports in the literature. [1][2][3][4] However, Geddes et al 5 reported a series of 5 such tumors in 4 patients. There are even rarer case reports of such mixed tumors in patients without definite evidence of NF-2.…”

Collision Tumour of Cerebellopontine Angle in a Patient without Neurofibromatosis Criteria: Case Report

“…Since the first description by Cushing and Eisenhart in 1938, just over a dozen case reports of mixed schwannomas and meningiomas (both components seen together in the same tumor) arising in patients with NF2 were reported [1]. The simultaneous occurrence of primary brain tumours of different histology in the same anatomical site its´ a rarely observed situation, more rarer particularly on the CPA [2,3].…”