Atherosis of Trophoblast Type: A Specific Form of Decidual Vasculopathy Distinct From Atherosis of Macrophage Type

Context.— There are 3 types of decidual vasculopathy, namely, acute atherosis, fibrinoid medial necrosis, and mural arterial hypertrophy. Persistence of vascular trophoblasts is also known to be related to maternal vascular malperfusion, but detailed study is lacking. Objective.— To define atherosis of trophoblast type and distinguish it from atherosis of macrophage type with clinical significance. Design.— A total of 1322 placentas from 2021 were collected with clinical, neonatal, and placental information, and routine placental pathology examination was performed. Decidual vasculopathy was classified on the basis of the new classification scheme including atherosis of macrophage type, atherosis of trophoblast type, fibrinoid medial necrosis, mural arterial hypertrophy, and mixed-type vasculopathy. The significance of these morphologic changes was examined on the basis of clinical, neonatal, and placental pathology features. Results.— Decidual vasculopathy is classified as classic type, mural hypertrophy, and mixed type. Classic-type vasculopathy is further separated as atherosis and fibrinoid medial necrosis. Atherosis is defined as atherosis of macrophage type and atherosis of trophoblast type. Each category of decidual vasculopathy was evaluated in association with maternal, neonatal, and placental pathologic findings. Atherosis of macrophage type and mixed-type vasculopathy showed statistically significant association with preeclampsia/pregnancy-induced hypertension, low birth weight, and low placental weight. Atherosis of trophoblast type was associated with lower placental weight but not with other specific clinical features. Neonates of female sex were associated with mural arterial hypertrophy. Conclusions.— Atherosis of trophoblast type is a distinct pathologic feature in late pregnancy, and it is associated with lower placental weight. New classification of decidual vasculopathy helps with better stratification and categorization of placental maternal vascular abnormalities of late pregnancy.