MR of fourth-ventricular epidermoid tumors.

Epidermoid tumors arising from the fourth ventricle are uncommon. Although they may grow to an enormous size in a very critical location, the majority of patients do not have the explosive symptoms and neurologic findings common to most fourth-ventricular tumors. We present one confirmed case and one highly suggestive case of epidermoid tumor of the fourth ventricle. Both were evaluated by MR imaging and demonstrate the typical features of these tumors.