PMC7771499_01
Preoperative brain neuroimaging showing an extra-axial vascular mass lesion involving the right cerebellopontine angle (CPA) with associated venous anomaly. (a) Brain computed tomography (CT) scan without contrast, (b) CT scan with contrast, (c) axial T2 weighted, (d) axial T1 weighted without contrast, (e) postcontrast axial T1 weighted, and (f) MR angiography. Double arrow: associated venous anomaly, arrow: sinusoid pools in the site of the lesion in the right CPA, asterisk: small intraparenchymal hematoma in the site of VP shunt insertion.
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F1
Urgent brain computed tomography (CT) scan showed hyperdense lesion of the right CPA, with an associated mass effect compressing the fourth ventricle and secondary acute hydrocephalus [Figure 1a and b]. T1- and T2-weighted images suggestive of hemorrhages of different ages [Figure 1c and d]. T2 gradient echo sequences showed multiple sinusoid-like channels and diffuse hemosiderin deposition. MRI sequences also showed signs of associated venous anomaly in the right cerebellar hemisphere [Figure 1e]. MR angiography showed sinusoid pools in the site of the lesion [Figure 1f], and digital subtraction angiography revealed occult lesion and confirming the presence of associated developmental venous anomaly.
Intraoperative views showing: (a) the gross appearance of the extra-axial lesion in the cerebellopontine angle, (b) dissection of the trigeminal nerve and the facial/vestibule-cochlear complex, (c) dissection of the lower cranial nerves and posterior inferior cerebellar artery. (d) Early postoperative brain magnetic resonance imaging showing total resection of the lesion. 5: Trigeminal nerve, 7/8: Facial/vestibulocochlear complex, LCN: Lower cranial nerves, PICA: Posterior inferior cerebellar artery
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F2
Dissection of the mass from the trigeminal, facial, vestibulocochlear, and lower cranial nerves was performed and total resection of the tumor was achieved [Figure 2a-c]. Postoperative brain MRI showed total resection of the mass [Figure 2d].
Histological examination showed a multilobulated lesion composed of sinusoidal vascular spaces of various sizes lined with a single layer of endothelial cells. These vascular spaces are separated by fibrous connective tissue. (a and b) H and E x200.
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F3
Intervening stroma was fibrocollagenous and devoid of nervous tissue, compatible with the diagnosis of a cavernoma [Figure 3].