Giant intradiploic epidermoid tumor of the occipital bone: case report. The authors describe a case of a giant intradiploic epidermoid cyst of the occipital bone with an intracranial extension in the posterior fossa and no signs of neurological involvement. The lesion started as a painless lump under the scalp. Roentgenographic and computed tomographic findings led to a correct diagnosis, and the complete removal of the cyst was accomplished, despite its large size. The total removal of these cysts is associated with a good prognosis. 