case_images: PMC11737897_01
case_images: MRI examination reveals an extra-axial cystic lesion appearing dark on T1-weighted images and bright on T2-weighted images.
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case_images: A magnetic resonance imaging (MRI) of the head revealed an extra-axial cystic lesion in the left cerebellopontine angle (Fig. 1), compressing the left cerebellar hemisphere posteriorly, displacing the pons to the right, narrowing and displacing the fourth ventricle to the right, causing non-communicating hydrocephalus.
case_images: Intraoperative and histopathological findings. (A) The cyst wall is seen adhering to the arachnoid layer in the CPA (arrow). (B) During dissection, the N. VII/VIII complex and N. V are visualized. Structures observed include (C) the lower cranial nerves with the arachnoid and cyst wall (arrow) and (D) the vertebrobasilar junction. (E) Microscopic examination shows a columnar epithelium with goblet cells (HE stain; 100x magnification). (Abbreviations: CPA: Cerebellopontine angle, N: Nerve, V: Trigeminal, VII: Facial, VIII: Vestibulocochlear, RVA: Right vertebral artery, LVA: Left vertebral artery, BA: Basilar artery, HE: Hematoxylin and eosin stain).
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case_images: We carefully identified the cystic wall, which is very adherent to surrounding structures (Fig. 2A). First, we encountered severe adherence from the cystic wall on the facial nerve; we removed the cystic wall to decompress the nerve, and further arachnoidal dissection to the deep structure to expose the trigeminal nerve (Fig. 2B). The lower border of the cyst around the lower cranial nerve and the vertebrobasilar complex is identified, and then the wall is carefully dissected to decompress the neural structures (Fig. 2C and D). Examination revealed a thin tumor wall, with microscopic features showing that the cyst wall consisted of fibrous connective tissue lined by a single layer of ciliated columnar epithelium and goblet cells (Fig. 2E).