Presentation
Increasing headaches.
Patient Data
There is expansion of the posterior part of the body of the right lateral ventricle. It is above the trigone and does not appear to have a colpocephaly configuration. The temporal horn is also distended but to a lesser degree.
MRI demonstrates that the expansion is caused by a very thin-walled (best seen on T2 fast spine echo sequences) cystic lesion which follows CSF on all sequences, including FLAIR and DWI.
Except for the location, the appearances are characteristic for a simple intraventricular cysts, sometimes referred to (perhaps more accurately in these cases) as CSF cysts, are uncommon but well described.
The absence of an enhancing component makes other lesions most unlikely.
Case Discussion
The patient went on to have endoscopic fenestration of the cyst, with histological confirmation of the diagnosis.
Pathology
Specimen type: arachnoid cyst fluid
The smear contains foamy macrophages, leptomeningeal cells and red blood cells. No malignant cells are identified.