Villitis of unknown etiology, chronic deciduitis, chronic chorioamnionitis and chronic histiocytic intervillositis in monozygotic and dizygotic twin pregnancies. A retrospective analysis of 16 cases

•In monozygotic twin placentas most chronic inflammatory lesions manifest concordantly.•In dizygotic gestations these diseases mostly show a discordant manifestation pattern.•Discordant manifestation of the placental lesions may contribute to discordant growth of the babies.•Chronic deciduitis is the chronic inflammatoric entity that displays a heterogenous distribution pattern in twin placentas.