Congenital immature teratoma of the fetal brain.

Congenital intracranial tumors are very rare and only account for 0.5-1.5% of all childhood brain tumors. Even rarer are those with prenatal manifestation. The most common of these present at birth are teratomas, which show divergent differentiation with 90% of them containing tissues from all three germ layers. We report a rare case of an intrauterine congenital immature teratoma in a female fetus at 23 weeks of gestation, which was sonographically diagnosed in vivo by detection of the tumor and associated craniomegaly. Because of the poor prognosis, termination of the pregnancy was induced by Rivanol instillation. The cerebral tumor was confirmed at autopsy and was not associated with any other malformations. Histological and immunohistochemical features of this tumor are presented.