PMC4287896_01
(a) CT scan at initial onset demonstrating left cerebellar hemorrhage with subarachnoid hemorrhage. (b) Left vertebral angiogram before first gamma knife radiosurgery showing a left cerebellar hemispheric AVM supplied by posterior inferior cerebellar artery (arrow). (c) Left vertebral angiogram at 3 years after first radiosurgery revealing residual nidus in the left cerebellar hemisphere (arrowhead). (d) Left vertebral angiogram obtained at 5 years after the second radiosurgery revealing no residual AVM nidus
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F1
The diagnosis of cerebellar and subarachnoid hemorrhage from AVM supplied by the posterior inferior cerebellar artery (PICA) was based on the findings of computed tomography (CT) [Figure 1a] and cerebral angiography. Four months after surgery, vertebral angiography demonstrated left cerebellar hemispheric AVM supplied by the PICA [Figure 1b]. Three years after the first radiosurgery, vertebral angiography showed a small residual nidus in the left cerebellar hemisphere [Figure 1c]. Vertebral angiography obtained at 5 years after the second radiosurgery revealed complete disappearance of the AVM [Figure 1d].
Axial T2-weighted MR image (a) and postcontrast T1-weighted MR image (b) demonstrating appearance of the enhanced lesion adjacent to the cyst formation in the left cerebellar hemisphere at 7 years after second radiosurgery. (c) CT scan showing an irregularly shaped, mixed density lesion with extensive edema in the left cerebellar hemisphere. (d) Postoperative gadolinium-enhanced T1-weighted MR image demonstrating total removal of the lesion
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F2
T1-weighted MR imaging obtained at 7 years after the second radiosurgery revealed an enhanced lesion adjacent to the cyst formation in the left cerebellar hemisphere [Figure 2a, b]. The patient was lost to follow up during the 18 months after the last examination. The patient subsequently presented with headache and nausea, which had persisted over 3 weeks, at age 34 years in the 32nd week of pregnancy, and was referred to our institution 9 years after the second radiosurgery. On admission, CT demonstrated an irregularly shaped, heterogeneous high density hematoma with perifocal edema in the vermis extending to the left cerebellar hemisphere [Figure 2c]. Postoperative MR imaging revealed total resection of the hematoma with the adjacent cyst [Figure 2d].
(a) Photomicrographs of the chronic encapsulated expanding hematoma demonstrating angiomatous abnormal vessels, multifocal hemorrhage, and coagulation necrosis. HE, original magnification x100. (b) Areas of coagulation necrosis and extensive hemorrhage. HE, original magnification x200. (c) Angiomatous region showing thickening of the vessel walls with hyaline degeneration and inflammatory infiltration. HE, original magnification x200. (d) Immunohistochemical examination demonstrating strong staining for CD34 in the microvasculature. Original magnification x200
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F3
Histological examination of the lesion obtained during surgery demonstrated encapsulated hematoma consisting of a dense collagenous outer layer and a granulated, newly vascularized, angiomatous inner layer with extensive multinodular hemorrhage at various stages of organization [Figure 3a]. Hemosiderin deposits and coagulation necrosis were also observed [Figure 3b]. The microvasculature in the inner layer demonstrated inflammatory infiltration in the vascular walls and thickening of the vessel walls with hyaline degeneration, which are characteristic findings of vasculitis [Figure 3c]. Immunohistochemical examination demonstrated strong staining for CD34 in the microvasculature [Figure 3d].