Intrapericardial teratoma diagnosed prenatally in a twin fetus.

Prenatal diagnosis at 32 weeks' gestation of an anteromediastinal tumor in a twin fetus allowed immediate neonatal intensive management after delivery at 34 weeks' gestation. At 48 h of age the patient underwent a median sternotomy; complete resection of the tumor was possible. Histologically, it was a mature teratoma. At age 1 year both twins are well.