Recurrent epidermoid

On the FLAIR scan there is a region of abnormal signal intensity, isointense to brain, to the right of the medulla. This could be related to abnormal soft tissue, or simply reflect artifact due to CSF pulsation. On the FSE T2-weighted scan, and the post-contrast T1-weighted scan, the question of subtle abnormal soft tissue in this region (nearly isointense with CSF) remains. The diffusion weighted scan is diagnostic in this instance, with several areas of marked hyperintensity seen within the subarachnoid space to the right of the medulla, consistent with an epidermoid.

Recurrent epidermoid
Part of the on-line supplement to Neuroradiology – The Essentials with MR and CT (© 2015)