Epidermoid cyst - middle cranial fossa


This is a wonderful exam case, as the location of the epidermoid is more typical of its main CT differential - an arachnoid cyst. Still, the imaging is obviously that of an epidermoid cyst, particularly of DWI / ADC, with the content demonstrating ADC values similar to white matter (~700 x 10-6 mm2/s). 

On follow-up imaging, the hippocampal signal on the right had returned to normal confirming that this was indeed post-ictal.