Placental chorioangioma is a benign mass derived from vessels within the placenta. Technically, it may be considered as a hamartoma (disorganized growth of normal tissue) rather than a true neoplasm. Chorioangiomas are reported to be present in about 0.6 - 1% of all placentas and are usually < 1 cm in diameter. Large chorioangiomas (>4-5 cm) are less common with an estimated incidence of 1 in 10,000 to 1/50,000 live births.
Large chorioangiomas may act as arteriovenous shunts and may not allow normal gas or nutrient exchange between the fetus and the mother. This may result in a number of potential fetal complications, including polyhydramnios (14%–28%), hydrops, intrauterine growth restriction (30%), and prematurity (40%), microangiopathic hemolytic anemia, thrombocytopenia, intralesional hemorrhage and in utero death. The combination of giant hemangioma, thrombocytopenia, and consumptive coagulopathy is called Kasabach-Merritt syndrome (KMS).
Antenatal diagnosis of placental chorioangioma is based on the ultrasound identification of a well-circumscribed hypoechoic mass located in the chorionic plate. Feeding vessels may or may not be distinguishable with color or pulsed Doppler. The number of feeding vessels may be a single pair (one artery, one vein), or complex.
The management of pregnancies diagnosed with placental chorioangioma is mostly expectant. Prenatal intervention may be necessary in cases presenting with severe polyhydramnios, pending or overt fetal heart failure, or maternal symptoms of cervical shortening or preterm labor, particularly if remote from viability. Antenatal management may include medical or instrumental treatment of polyhydramnios or symptomatic treatment of fetal anemia. Quintero and collaborators first described the successful fetoscopic management of a placental chorioangioma by occluding the feeding vessels to the mass. Although the fetus did not survive because of advanced heart failure, it showed that devascularization of a placental chorioangioma is possible. Fetoscopic devascularization of placental chorioangiomas is currently being offered as a management option in selected cases.