Placental mesenchymal dysplasia.

Placental mesenchymal dysplasia is a rare placental lesion characterized by stem villous cystic dilation and vesicle formation, placentomegaly, and vascular abnormalities. It can be associated with growth restriction, stillbirth, Beckwith-Wiedemann syndrome, and some chromosomal abnormalities, and needs to be distinguished from its main differential diagnosis, hydatidiform mole.