[Placental teratoma: differential diagnosis with fetal acardia].

The acardiac fetus is a rare congenital malformation observed only in monozygotic twin pregnancies (1/35.000 pregnancies). Placental teratoma is extremely rare (less than 20 cases have been reported in the literature since 1925). A case of placental teratoma, misdiagnosed as fetus acardius amorphus, is presented with ultra-sound follow-up, delivery and outcome of the normal fetus. Pathological findings, histogenesis, differential diagnosis with the acardiac fetus and finally review of the literature will be discussed.