Degenerative type of placental chorioangioma requiring fetal blood transfusion.

We experienced a case with fetal hydrops, polyhydramnios, and a well-defined oval anechoic lesion of approximately 9 cm in size, without blood flow at 26 weeks' gestation. As increased middle cerebral artery peak systolic velocity, the fetal hydrops was caused by a placental tumor such as a chorioangioma; however, the tumor was atypical. Fetal blood hemoglobin was 8.3 g/dl on percutaneous umbilical cord blood sampling. After erythrocytes transfusion to the fetus, the mother normally delivered at 38 weeks' gestation. The placental tumor was histologically diagnosed as a necrotic chorioangioma. Obstetricians should note such atypical chorioangiomas when differential diagnosis of placental tumors.