Objective: Placental mesenchymal dysplasia (PMD) is an uncommon vascular anomaly of the placenta characterized by mesenchymal stem villous hyperplasia. Its main sonographic feature is a thickened placenta with hypoechoic areas, and an accurate sonographic diagnosis is challenging. The aim of this study was to report 2 cases of PMD and discuss the differential diagnosis of its sonographic features.
Methods: Cases of placental masses were studied by 2-dimensional (2D), 3-dimensional (3D), and color Doppler imaging.
Results: In case 1, a thick placenta with multiple hypoechoic areas was noted at 13 weeks' gestation. At 19 weeks, the multicystic area, clearly demarcated from a normal-looking placenta, measured 6.5 x 8.5 cm and enlarged gradually. The patient gave birth to a 625-g female neonate after spontaneous labor at almost 26 weeks' gestation. In case 2, a first sonographic examination at 25 weeks' gestation revealed a thickened placenta with hypoechoic areas and a fetus with a single umbilical artery and a ventricular septal defect. At 27 weeks, the abnormal area of the placenta measured 14.5 x 7.5 cm. At 32 weeks' gestation, a caesarean delivery was performed because of a nonreassuring fetal heart tracing, and a 1415-g female neonate was delivered. Both cases were evaluated by 2D, 3D, and color Doppler imaging, and the pathologic features of both placentas were consistent with PMD.
Conclusions: Placental mesenchymal dysplasia should be considered in the differential diagnosis of every placental mass, especially in cases of multicystic placental lesion with lack of high-velocity signals inside the lesion, and a normal karyotype.