**9. Placental chorioangioma**

Chorioangioma is a benign vascular tumor, found in approximately 1% of all pregnancies [50]. It was firstly described in 1798 by Clarke [51]. This pathology is a malformation of the primitive angioblastic tissue of the placenta perfused by the fetal circulation. It is rarely clinically significant and is usually discovered incidentally. Most of the chorioangiomas have small

**Figure 6.** Ultrasound color Doppler image of a chorioangioma diagnosed in the second trimester of pregnancy.

dimensions. However, large chorioangiomas have been associated with a range of fetal conditions (fetal anemia, thrombocytopenia, hydrops, hydramnios, intrauterine growth retardation), including prematurity and stillbirth [1]. Also, large tumors can degenerate in necrosis, calcification, hyalinization, or myxomatous degeneration. Typically, on the ultrasound, a chorioangioma is located near the insertion of the cord into the amniotic cavity, as a hypoechoic, rounded mass with usually anechoic cystic areas with low resistance pulsatile flow (e.g., **Figure 6**) [52]. In rare cases the tumors are pedunculated. As differential diagnosis, subamniotic hematoma, partial hydatidiform mole, submucosal uterine fibroid, placenta teratoma, and atypical placental venous lake should be considered [53].
