Presentation
Headache
Patient Data
A lobulated border mass lesion in extra-axial CSF spaces of skull base centered in suprasellar cistern with extension to the prepontine cistern, pituitary fossa as well as extra-axial CSF space of anterior and medial aspect of the temporal and inferior aspect of frontal regions is noted. The lesion has resulted in the expansion of CSF spaces with gradual mass effect, particularly over pons, midbrain and pituitary gland. The lesion is insinuating between structures and encasing the circle of Willis vessels. The mass is of low T1 signal (slightly higher than CSF), hyperintense on T2, dirty signal on FLAIR. While showing similar ADC values compared to the adjacent brain parenchyma (not show), the lesion is very bright on DWI. On post-contrast images, a thin rim and septal enhancement is noted. (see Intracranial epidermoid cyst)
Hydrocephalus without CSF seepage (involving lateral and third ventricles) is seen; however, the lesion is far from the cerebral aqueduct.
Mucosal thickening in ethmoid air cells, right frontal and both maxillary sinuses associated with air-fluid level in maxillary sinuses are also seen.
Case Discussion
Key teaching points:
- insinuating nature of epidermoid cysts and gradual mass effect
- DWI and ADC map characteristics of epidermoid cysts (bright on DWI, similar in signal to adjacent brain parenchyma on ADC map)
- signal intensity relatively the same as CSF on many other sequences
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