Discordance of Twin Placentas for Multifocal Eosinophilic/T-cell Chorionic Vasculitis.

Eosinophilic/T-cell chorionic vasculitis (ETCV) is an idiopathic placental lesion characterized by chorionic vasculitis composed predominantly of eosinophils and CD3+ T lymphocytes. It usually presents as a unifocal lesion, but a subset have multifocal involvement. We report 4 Di-Di and 2 Di-Mo twins sharing fused placental discs with discordant circulatory involvement by multifocal ETCV. The findings are difficult to explain by sampling alone. The limitation of ETCV to 1 fetus's vascular territory in monozygotic twin pregnancies is difficult to explain but could provide insights into the fetal immune system and the etiology of ETCV.