Epidermoid cyst - posterior cranial fossa

Case contributed by Ammar Haouimi
Diagnosis almost certain


Chronic headaches, vertigo, and peripheral facial nerve palsy. The patient had history of surgery at the posterior cranial fossa 20 years ago.

Patient Data

Age: 65 years
Gender: Male

The MRI sequences demonstrate an extra-axial mass of irregular margins filling the posterior fossa cisterns, mainly the subpontine, prepontine, and supracerebellar cisterns with extension to the 4th ventricle which is dilated. It is of low signal intensity on T1WI, heterogeneous low signal on FLAIR and high signal on T2WI with no enhancement following IV contrast. It shows a high signal on DWI with low ADC (restricted diffusion).

A mass effect is noted on the brainstem and right cerebellar hemisphere which shows an area of encephalomalacia and gliosis from the previous surgery. Mild dilatation of the 3rd and lateral ventricles.

Case Discussion

Typical MRI features an epidermoid cyst of the posterior cerebral fossa. DWI an important sequence to differentiate an epidermoid cyst from an arachnoid cyst. Given the remote history of posterior fossa surgery, the possibility of epidermoid recurrence is considered as it is a slowly growing mass lesion or acquired epidermoid, although rare. 

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.