Epidermoid tumor of the cerebellopontine angle: diagnostic value of computed tomographic metrizamide cisternography.

The extent of spread of an epidermoid tumor in the posterior fossa may be difficult to discern preoperatively. Conventional computed tomographic (CT) studies may not outline the tumor capsule, and the low attenuation of the tumor itself may not allow a distinction from cerebrospinal fluid. CT metrizamide cisternography was helpful in delineating the inferior pole of an epidermoid tumor, which could then be delivered through a transtentorial approach.