PMC3740615_01
Head CT without contrast demonstrating hemorrhage in the left occipital pole
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F1
On computed tomography (CT) imaging [Figure 1], he was found to have a left occipital hemorrhage and was transferred to this facility for further work-up and management.
T2 FLAIR MRI revealing 1 cm hyperintense parasellar mass with a possible fluid-hematocrit level (a) and T1 weighted image with gadolinium that demonstrates a nonenhancing parasellar mass (b)
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F2
FIESTA MRI revealing the course of the right third nerve as it meets the arachnoid cyst
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F3
T2 flair imaging without diffusion restriction that appeared to compress the right third cranial nerve [Figure 3]. These findings were concerning for a thrombosed PCommA aneurysm.
Intraoperative images demonstrating a frontotemporal approach to the middle fossa. Internal carotid artery and optic nerve (a). Arachnoid cyst bounded inferiorly by the internal carotid artery (b)
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F4
Intraoperatively, a right parasellar cystic lesion resembling an arachnoid cyst was identified, medial to the third nerve, which was pushed laterally [Figure 4].
Formalin-fixed paraffin-embedded slides stained with hematoxylin and eosin. Sections showed a fragment of dense fibrous connective tissue attached to a long thin fibrous piece of tissue. There was no inflammation or other pathological changes. The thin fibrous material is likely leptomeningeal tissue, while the more fibrous fragment could be a portion of dura or fibrotic leptomeninges. (H and E, x200)
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F5
The wall of the cyst was then carefully dissected and sent for permanent section analysis, which confirmed the diagnosis of an arachnoid cyst [Figure 5].
3-month postoperative MRI demonstrating resolution of T2 FLAIR signal abnormality consistent with complete surgical resection of the right parasellar arachnoid cyst
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F6
MRI at that time revealed no evidence of a residual or recurrent arachnoid cyst [Figure 6].