Synchronous Tumors of the Cerebellopontine Angle

Background: Synchronous tumors of the cerebellopontine angle (CPA) are exceedingly rare, and inconsistently described. We report two cases of contiguous vestibular schwannoma (VS) and meningioma, as well as perform a systematic literature review of all multiple CPA tumors.

Methods: Retrospective chart review and systematic review of the literature.

Results: During the past year we encountered two patients, a 64-year-old woman and a 42-year-old man who presented with symptoms referable to the CPA with hearing loss and instability. MR imaging in both patients revealed two separate contiguous tumors in both patients. Retrosigmoid craniotomy and tumor removal in each case revealed VS and meningioma. Systematic literature review identified 41 unique English-language publications describing a total of 46 patients with multiple CPA tumors, in addition to the two present cases. By Frassanito’s criteria, there were four concomitant tumors (8%), 16 contiguous tumors (33%), three collision tumors (6%), 13 mixed tumors (27%), and 11 tumor-to-tumor metastases (23%). Extent-of-resection was gross total in 16 (33%), subtotal in 15 (31%), and not reported in seven (15%). Unfavorable House-Brackmann grade III–VI function was documented in 33% of VS-meningioma patients, a marked increase from the observed range in isolated VS.

Conclusion: The terminology used to classify multiple CPA tumors is heterogeneous, confusing, and often inaccurate. We recommend a simplified taxonomy, in which the vast majority of multiple CPA tumors are classified as synchronous tumors, with the specific terminology schwannoma with meningothelial hyperplasia or tumor-to-tumor metastases recommended for rare, specific circumstances. Schwannoma with meningothelial hyperplasia is strongly associated with NF2, and should prompt appropriate screening, particularly in young patients. The small but clinical significant increase in poor facial nerve outcomes may be suggestive of increased invasiveness or adhesiveness at the facial nerve-tumor interface, potentially attributable to a paracrine mechanism that simultaneously drives multiple tumor growth.

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