Villitis of Unknown Etiology and Massive Chronic Intervillositis.

Villitis of unknown etiology (VUE) is a common lesion affecting from 6.6% to 33.8% of third-trimester placentas. VUE needs to be distinguished from villitis of infectious etiology, most commonly cytomegalovirus and syphilis. Clinically, this lesion is associated with intrauterine growth retardation, intrauterine fetal demise, fetal neural impairment, maternal alloimmune and autoimmune disease, and maternal hypertension. It has a tendency to recur in subsequent pregnancies. Massive chronic intervillositis (MCI), also known as chronic histiocytic intervillositis, is a rare lesion that has an unclear relationship with VUE. MCI is associated with recurrent abortions.