Abnormally large placenta associated with Beckwith-Wiedemann syndrome.

A 37-year-old G1-P1 was diagnosed by ultrasonography at 26 weeks of gestation as having an abnormally large placenta with hemangiomas and a fetus associated with exomphalos. Placental protein 5 levels were relatively high in placental protein levels in maternal serum. The infant, delivered by cesarean section at 34 weeks, had the typical clinical features associated with Beckwith-Wiedemann syndrome. The abnormally large placenta weighed 1,492 g, measured 25 X 25 X 5.1 cm, and featured multiple hemangiomas. Microscopic placental features included edematous villi, increased fibrin deposition, intervillous thrombi, and multiple angiomatous and cellular chorangiomas.