Immature teratoma producing alpha-fetoprotein without components of yolk sac tumor in the pineal region.

A case of pineal region tumor in a 9-year-old boy with a high serum alpha fetoprotein (AFP) level is reported. The serum levels of beta-human chorionic gonadotropin (HCG) and placental alkaline phosphatase (PLAP) were not elevated. The tumor was composed of radiologically different components and was removed surgically. Postoperative radiation therapy was performed and the serum level of AFP gradually declined to the normal range. The pathological diagnosis was immature teratoma, and no elements of yolk sac tumor or embryonal carcinoma were found. In the immunohistochemical study, AFP was detected in the cytoplasm of gastrointestinal-type epithelium and primitive neuroepithelial element. This is considered a rare case of intracranial immature teratoma in which AFP was detected immunohistochemically in the columnar epithelium and immature neural tissue.