PMC9560546_01
Preoperative imaging. (A) Head plain computed tomography showed a diffuse subarachnoid hemorrhage. (B) Lateral 3D reconstruction of right ICA angiogram showed a multilobar fusiform aneurysm on the right M2-3 junction (arrow). (C) Magnification of lateral 3D reconstruction of right ICA angiogram clearly indicates multifocal fusiform aneurysm at the M2-3 junction (arrow). Arrow head shows the right M2. (D) Computed tomography angiogram showed no obvious dissecting changes (e.g., aneurysm formation) from the common carotid artery to the intracranial internal carotid artery.
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Coma Scale (GCS) E1V1M2) and anisocoria. Computed tomography (CT) imaging showed a diffuse SAH (right > left) (Fig. 1A). Angiogram revealed a multilobar fusiform aneurysm on the right MCA (at the M2 and M3 bifurcation) (Fig. 1B, C) and an irregular small aneurysm on the top of the basilar artery. No obvious dissecting changes such as aneurysm formation were observed from the common carotid artery (CCA) to the internal carotid artery on CT angiogram (Fig. 1D).
Microscopic operative view and postoperative imaging. (A) A multifocal fusiform aneurysm was observed at the bifurcation of the M2-3 junction. Trapping of the M2 segment was performed (arrowhead). (B) Intravenous indocyanine green injection revealed excellent patency of the STA-MCA bypass. Arrows and arrowheads indicate the STAs and MCAs, respectively. (C) Computed tomography angiogram showed disappearance of the aneurysm.
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A multifocal fusiform aneurysm was observed at the M2-3 junction (Fig. 2A). We confirmed excellent patency of the STA-MCA bypass by intravenous indocyanine green injection (Fig. 2B). On postoperative day 1, CT angiogram showed aneurysm disappearance (Fig. 2C).
Pathological findings. (A) Hematoxylin-eosin staining showing an overall view of the collected specimen (20x magnification). (B) Hematoxylin-eosin staining (100x magnification) showed proliferation of atypical spindle-shaped cells with enlarged nuclei in the lumen of the affected middle cerebral artery. (C, D) Infiltration of atypical spindle-shaped cells beyond the smooth muscle of the tunica media to the tunica adventitia. (D) Elastica van Gieson staining (100x magnification) showing disappearance of the lamina elastica interna in the same area. (E) At the ruptured site, the lamina elastica interna had disappeared, creating an aneurysm with thrombus formation in the lumen.
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Microscopic hematoxylin-eosin staining showed proliferation of atypical spindle-shaped cells with enlarged nuclei in the lumen of the affected MCA (Fig. 3A, B). Elastica van Gieson staining showed disappearance of the lamina elastica interna (Fig. 3C, D). At the rupture site, the lamina elastica interna had disappeared, forming an aneurysm (Fig. 3E).
Immunohistological findings. Immunostaining showed (A) CD34 (-), (B) CD31 (+-), (C) ERG (+), (D) SMA (+-), (E) MDM2 (+), (F) CDK4 (+, slightly), and (G) MIB-1 index 13.9% (A-E, G: 200x magnification, F: 400x magnification, respectively).
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Immunostaining showed CD34 (-), CD31 (+-), ERG (+), MDM2 (+), CDK4 (+), SMA (+-), MIB-1 index 13.9%, factor VIII (+-), and desmin (-) (Fig. 4).