Constellation of MRI imaging features of an expansile non-enhancing lesion in mid portion of right petrous temporal bone showing T2w hyperintense signals with partial suppression of signal on FLAIR imaging and with restricted diffusion are consistent with a perilabyrinthine epidermoid cyst (classical imaging features of epidermoid cyst).

Our patient had a right facial palsy secondary to erosion of labyrinthine segment of facial nerve canal by the expansile, lytic lesion.

An intraosseous location, especially in a perilabyrinthine location is a rare site of epidermoid cysts. However, they show similar MRI imaging features as elsewhere in the body. The close proximity of the lesion to the vestibulocochlear apparatus can lead to symptoms related to facial palsy, balancing problems and hearing impairment.