Presentation
Asymptomatic patient.
Patient Data
A large high T2, low T1 signal mass is present in the pineal region. The pineal gland is difficult to identify, but may be displaced superiorly by the mass (best seen on sagittal T1 images). The mass flattens the tectum of the midbrain and results in compression of the aqueduct. Note: an endoscopy tract is seen traversing the right frontal lobe with flow artefact through the floor of the third ventricle in keeping with a third ventriculostomy.
The mass demonstrates 'dirty' signal on FLAIR and no contrast enhancement. On DWI it demonstrates high signal consistent with a degree or restricted diffusion.
The features are those of an epidermoid cyst.
A near-CSF intensity mass is located in the quadrigeminal cistern ( * ) displacing the pineal gland superiorly (yellow). The internal cerebral veins (blue) are displaced superiorly, whereas the basal veins of Rosenthal (red) are displaced laterally. The mass demonstrates very high signal on DWI.
Case Discussion
This case illustrate typical appearances of an intracranial epidermoid cyst, albeit in an unusual location. It highlights the need to think simultaneously in terms of 'regional differential' and 'appearance differential'.
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