Presentation
Presented with vestibular symptoms.
Patient Data
There is a well-delineated lobulated lesion that is insinuating along with the basal cisterns, seen in the right cerebellopontine angle. The lesion is heterogeneous and follows CSF signal intensity on T1W and T2W imaging, partially attenuated on FLAIR, and shows restricted diffusion and showing ADC similar to brain parenchyma. The Post-contrast scan shows no enhancement. Imaging findings are suggestive of an epidermoid cyst.
The lesion is compressing the right cerebral peduncle, midbrain, pons, cerebellar hemisphere, vermis, and 4th ventricle.
Case Discussion
Epidermoid cyst is the 3rd most common cerebellopontine angle tumor after schwannoma and meningioma. The closest differential of an epidermoid cyst is an arachnoid cyst and DWI and ADC sequences are useful in distinguishing between these two lesions. An arachnoid cyst shows no restriction of diffusion whereas an epidermoid cyst does. The ADC of arachnoid cyst is similar to stationary water, whereas the ADC of epidermoid is similar to the brain parenchyma.