PMC9174606_01
Preoperative hearing and imaging scans. (A) Preoperative pure tone threshold audiometry demonstrated profound mixed hearing impairment of the right ear. (B-F) MRI scan revealed a mass with a maximal diameter of 5.0 cm at the right cerebellopontine angle with petrous bone invasion. The lesion exhibited low- to iso-intense on T1-weighted images (B), iso- to high-intense on T2-FLAIR images (C), mixed intense on constructive interference in steady state (CISS) images (D), and heterogeneously enhanced after Gd-DTPA administration (E,F). (G) In the CT scan, we observed an enlargement of the right IAC with significantly bony destruction of the temporal apex (white arrows) and a slightly high ride of the jugular bulb (white triangle).
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F1
On admission, neurological and physical examination revealed profound mixed hearing impairment of the right ear (116 dBHL; Figure 1A). Magnetic resonance imaging (MRI) revealed a dumbbell mass with a maximal diameter of approximately 5.0 cm at the right cerebellopontine angle (CPA) and the temporal bone (Figures 1B-F). The lesion compressed the brainstem significantly and exhibited low- to iso-intense on T1-weighted images and iso- to high-intense on T2 fluid-attenuated inversion recovery images and heterogeneously enhanced after gadolinium-diethylenetriamine pentaacetic acid administration (Figures 1B-F). In the computed tomography (CT) scan, we observed an enlargement of the right IAC with significantly bony destruction of the temporal bone (Figure 1G). There was suspicious soft tissue in the mastoid cells, which was later proved to be part of the tumor during the surgery (Figure 1G).
Reconstruction tumor model, imaging scan and pathological examination after surgery. (A) Three-dimensional tumor model was reconstructed based on preoperative MRI and CT scan to demonstrate the spatial relationship of the tumor, adjacent nerves, arteries, and veins. (B) Postoperative MRI scan exhibited near-total resection of GVS in the posterior cranial fossa. (C,D) Pathological examination exhibited typical Verocay bodies in Antoni A region with positive S100 immunoactivity (C. H&E staining; D. S100b+ cells in IHC. Scale bar, 50 mum). Abbreviations, AICA, anterior inferior cerebellar artery; N., nerve; SPS, superior petrous sinus. (E-H). High immunoactivity of Iba-1 and TNFalpha in the tumor. (E) Iba-1 expression in Antoni A region; (F) TNFalpha expression in Antoni A region; (G) Iba-1 expression in Antoni B region; (H) TNFalpha expression in Antoni B region. Scale bar, 50 mum. Abbreviations, Iba-1, ionized calcium binding adaptor molecule 1; TNFalpha, tumor necrosis factor-alpha.
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F2
Based on MRI and CT scans, BrainLab iPlan Stereotaxy software (version 3.0.6; BrainLab, Munich, Germany) was applied to reconstruct the three-dimensional model to demonstrate the spatial relationship of the tumor, adjacent nerves, arteries, and veins (Figure 2A). Postoperative MRI confirmed the extent of microsurgical resection (Figure 2B), and histopathological examination demonstrated typical Verocay bodies in the Antoni A region in hematoxylin and eosin staining with S100b+ in immunohistochemistry (Figures 2C,D). Compared with the control subject (data not shown), obvious higher density of Iba-1 positive cells (Figures 2E,G) was observed in both the Antoni A and B regions with higher expression of TNFalpha (Figures 2F,H), which also exhibited typical morphology of hyperplastic macrophages and microglia.
Consecutive follow-up MRI. (A) Presurgical scan; (B) MRI scan after microsurgery; (C) MRI scan one month after gamma knife radiosurgery; (D) MRI scan one year after gamma knife radiosurgery. (E) the comparison of MRI findings between pre-surgical scan and the scan one year after gamma knife radiosurgery.
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F3
One month after GKRS, postoperative MRI demonstrated that the petrous part of the tumor had asymptomatic enlargement and degeneration of its central region (Figure 3). One year later, the tumor showed shrinkage of the residual lesion and further cystic degeneration (Figures 3D,E).