Not All Nerve Sheath Tumors Are Schwannomas: Case Report of a Rare Meckel's Cave Hemangioblastoma and Review of the Literature

Introduction: Central nervous system hemangioblastomas are typically cystic lesions with a mural nodule in the cerebellum or spinal cord that occur sporadically or with Von Hippel Lindau (VHL) disease. Cranial nerve hemangioblastomas are an incredibly rare entity and present both a diagnostic and surgical challenge given their intimate association with skull base vasculature and location within narrow operative corridors. Meckel's cave provides additional risk acting as a conduit to the cavernous sinus and prepontine cistern, thereby facilitating adherence to multiple cranial nerves and brainstem with modest tumor growth.

Objectives: To present a rare case of a trigeminal nerve hemangioblastoma and systematically review the literature

Methods: A retrospective chart review was performed of our case followed by a literature review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

We present a 61-year-old male with chronic V1-V2 facial numbness, decreased visual acuity, and headaches. He has no personal or family history of VHL nor polycythemia on routine laboratory studies. Neuroimaging revealed a bilobed, gadolinium-enhancing lesion along the right trigeminal nerve extending into Meckel's cave and ipsilateral cavernous sinus at the level of the foramen ovale ([Fig. 1]).

Results: After unsuccessful stereotactic radiosurgery to a suspected trigeminal schwannoma, the patient underwent a right subtemporal craniotomy with a transpetrosal approach for gross total resection. Intraoperatively, the tumor was adherent to the trigeminal nerve and cavernous sinus. He did not undergo further radiation therapy. Pathology was consistent with a WHO grade 1 hemangioblastoma ([Fig. 2]).

Systematic literature review revealed only three cases of trigeminal nerve hemangioblastoma in addition to the current study ([Figs. 3], [4]). No cases were associated with VHL. These lesions demonstrated variable radiographic appearance including two tumors without the classic associated cyst. Use of a combined skull base approach with retrosigmoid craniotomy depended on the extent of cerebellopontine tumor extension. Otherwise, surgical approaches utilized a subtemporal craniotomy with some form of petrosectomy to access Meckel's cave. All cases achieved a gross total resection without recurrence to date. Literature review further discovered 13 cranial nerve hemangioblastomas not specific to the trigeminal nerve, including the optic nerve (10), the vestibulocochlear nerve (2), and the trochlear nerve (1). 9 of these 13 lesions had an association with VHL. A 50% mortality rate was found for those lesions whose radiographic appearance was a solid enhancing mass.

Conclusion: We present a unique case of a solid trigeminal nerve hemangioblastoma in a 61-year-old patient without VHL, previously treated for a suspected schwannoma. Our patient is the fourth case documenting this rare entity. Early, accurate diagnosis is key for achieving gross total resection without iatrogenic cranial nerve deficits, thus hemangioblastoma should remain in the differential diagnosis for non-syndromic patients who present with chronic trigeminal nerve deficits and a solid mass with T2-weighted flow voids. Despite its rarity, our case and the literature demonstrate that gross total resection of these highly vascularized tumors is possible utilizing traditional open skull base techniques that provide access to Meckel's cave.

Fig. 1 Pre-operative MR Brain demonstrating (A) Axial T2-weighted, (B) Axial Gadolinium-enhanced, and (C) Coronal Gadolinium-enhanced views of a solid homogeneously enhancing lesion with a central flow void (red arrow) arising from Meckel's cave with posterior extension into the prepontine cistern (blue arrow) and ipsilateral cavernous sinus (yellow arrow).

Fig. 2 Pathology consistent with neoplastic stromal cells with clear cytoplasm (A) in a background network of numerous thin-walled capillaries (B). Specimen was positive for inhibin while negative for EMA and S100 stains (C).

Fig. 3 PRISMA diagram for systematic literature review of all trigeminal nerve hemangioblastomas documented within the English literature.

Fig. 4 Table of clinical characteristics. Abbreviations: Von-Hippel-Lindau (VHL); Magnetic Resonance Imaging (MRI); Cavernous Sinus (CS); Extent of Resection (EOR); Partial Labyrinthectomy Petrous Apicectomy (PLPA); Gross Total Resection (GTR); Subtotal Resection (STR); Subarachnoid Hemorrhage (SAH); Cranial Nerve (CN); Whole Brain Radiation Therapy (WBRT); Ventriculoperitoneal (VP).

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Artikel online veröffentlicht:
15. Februar 2022