PMC4235114_01
(a) CT showing SAH dominantly on the right side. (b) 3D-CTA showing a dilatation of M2 of the right MCA. Two small notches can be seen on the main lesion (arrows). (c) MRI 4 months before SAH showing an abnormality on the right M2 portion (arrow). (d) MRI on admission showing a dilatation of M2 (arrow)
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F1
MCA accompanied by two small notches [Figure 1b]. Magnetic resonance imaging (MRI) performed 4 months prior to the episode had already revealed the irregular wall of the right M2 [Figure 1c]. MRI performed at admission showed the same findings as those of 3D-CTA [Figure 1d].
Angiograms with right (a) and left (b) anterior oblique views, showing an aneurysmal dilatation of the right M2 (arrows)
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F2
Cerebral angiography revealed the dilated M2 of the right MCA [Figure 2].
Photograph of the resected lesion showing a dilated white MCA trunk with two red protrusions
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F3
The lesion consisted of a dilated arterial trunk with a whitish, thickened wall and two protrusions with red walls on the main lesion [Figure 3].
Microphotographs of samples stained with Elastica van Gieson stain (a, c, e) and immunostained with anti-alpha-smooth muscle actin antibody (b, d). Cross-section of large (a, b) and small (c, d) protrusions, and a dilated arterial trunk between the two protrusions (e) are presented. Figures (a, c, e) demonstrating disruption of the internal elastic lamina (arrows) and intimal thickening (asterisk). The cross-section at the site of the large protrusion (b) showing that the lesion has an intimal flap (arrowheads) without the existence of smooth muscle cells positive for anti-alpha-smooth muscle actin. The small protrusion (d) has no intimal flap x40
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F4
Pathological examination of the resected lesion showed a disrupted internal elastic lamina and intimal thickening of the main trunk [Figure 4e]. The large protrusion on the main trunk had a dissected intima without smooth muscle cells stained with anti-alpha-smooth muscle actin antibody [Figure 4a, b]. In contrast, the small protrusion had no intimal flap, and no internal elastic lamina was observed in the dome [Figure 4c and d].