Rare frontal lobe intraparenchymal epidermoid cyst with atypical imaging.

Epidermoid cysts are slow-growing benign tumors derived from ectodermal tissue that are hypothesized to have been inwardly displaced from the ectodermal surfaces during embryologic development. These cysts represent 1% to 2% of all intracranial tumors, and occur most commonly in the cerebellopontine angle, parasellar region, and subarachnoid spaces of the basal cisterns. Epidermoid cysts that are exclusively intraparenchymal are very rare, and can be difficult to diagnose as they often do not have classic radiologic findings, and share many similar radiologic features to other tumors such as astrocytomas, arachnoid cysts, dermoid cysts, and cavernomas. The authors present a patient with a rare intraparenchymal epidermoid cyst of the frontal lobe with atypical imaging features.