Congenital brain tumors (CBTs), defined as tumors presenting within 60 days after birth. Congenital central nervous system (CNS) tumors are rare. The incidence of brain tumors in newborns is 0.34 per million live births and they represent 0.5%-1.5% of all pediatric CNS tumors. Many of the congenital brain tumors often result in intrauterine fetal demise, thus making the accurate assessment of the true incidence difficult

In 1980 Hoff et al were the first to describe a brain teratoma diagnosed by ultrasound (US) in a fetus with 28 wk of gestation. Since then, other cases of congenital brain tumors have been reported during pregnancy. Teratomas and gliomas are the most frequent of them.

Modern US machines and routine US scanning during pregnancy allows early diagnoses of these tumors during fetal period. The association among US and magnetic resonance image (MRI) has permitted more precise diagnoses of the congenital CNS tumors during pregnancy. US imaging is the main method used to establish a correct diagnosis during pregnancy, once a solid, cystic, or calcified lesion has been observed. The associated abnormalities include macrocrania or local skull swelling, secondary hydrocephalus, intracranial hemorrhage, epignathus, polyhydramnios, heart failure by high-cardiac output, and hydrops.

However, the definitive diagnosis is only confirmed after birth by histology. In majority of cases their prognosis is poor. Neonates generally die shortly after birth, being the survival rate about 28%. Congenital brain tumors are usually sporadic and are not associated with other malformations.

The clinical aspects of congenital CNS tumors are entirely different from those found in older children or adults.

Congenital CNS tumors are divided into teratomas (most frequent described), and nonteratomatous tumors, including neuroepithelial tumors (choroid plexus papilloma, medulloblastoma, astrocytoma), mesenchymal tumors (such as craniopharyngioma), and others of different origin.

Fetal and/or maternal exposure to exogenous factors, including drugs, viruses, and ionizing irradiation, may initiate the biological mechanisms responsible for tumor formation. Developmental errors during embryonic and fetal maturation may also result in congenital tumors.

When an intracranial tumor is suspected, the option for termination of pregnancy should be offered, if legally possible. If termination of pregnancy is not allowed, cesarean section may be considered. In patients with severe hydrocephaly and/or macrocephaly, the possibility of dystocia should be contemplated and cephalocentesis considered for maternal reasons.

Teratomas are the most frequent type of congenital CNS tumors. They represent approximately 62% of all types of brain tumors diagnosed during pregnancy. The majority of fetal brain teratomas is histologically benign.