Exaggerated Placental Site Reaction (Syncytial Endometritis)
High power view showing numerous multinucleated intermediate trophoblastic cells in a case of exaggerated placental site reaction. It regresses spontaneously without any adverse effects. Differential diagnosis is with placental site trophoblastic tumor (PSTT). The presence of a mass, increased mitotic activity, destructive invasion of myometrium and necrosis favor PSTT.