Posterior fossa epithelial cyst of ectodermal origin

The case of a large ventral cyst of the posterior fossa of probable ectodermal origin in a 33-year-old patient is presented. Intracranial epithelial cysts are rare, and their histogenesis is a subject of controversy. Previous reports have hypothesized either a neuroepithelial or endodermal origin for the majority of these cysts. This case is unusual because it is the first case, to our knowledge, where melanocytes and melanin have been demonstrated within the cyst wall. These findings suggest an ectodermal origin for this cyst.