chorioangioma

noun

cho·​rio·​an·​gi·​o·​ma -ˌan-jē-ˈō-mə 

plural chorioangiomas also chorioangiomata -mət-ə 

: a benign vascular tumor of the chorion

Chorioangiomas occur in up to 1 percent of pregnancies, but those associated with nonimmune fetal hydrops are usually more than 5 cm in diameter and should have been visible on prenatal ultrasonograms or in the placenta at delivery.

—Linda J. Heffner et al., The New England Journal of Medicine