Intracranial immature teratoma with syncytiotrophoblasts and tumor marker positive intestinal lining cells.

Intracranial teratomas are rare entities that can present as a pure type or as mixed germ cell tumor. Cases of mixed germ cell tumor composed of immature teratoma and choriocarcinoma have been reported. Also, immature teratoma can be mixed with only syncytiotrophoblasts. We report a case of immature teratoma with syncytiotrophoblasts of the brain discovered in a 3-year-old male baby. Serum human chorionic gonadotrophin (hCG) was normal and serum alpha-fetoprotein (AFP) was elevated. The tumor was mainly composed of intestinal glands, and neither endodermal sinus tumor nor embryonal carcinomatous elements were found. The cells lining the intestinal glands were positive for hCG and AFP. These findings suggest that the syncytiotrophoblasts are differentiated from the endoderm and AFP is not necessarily a marker exclusive to endodermal sinus tumor or embryonal carcinoma.