Chronic Histiocytic Intervillositis: From Microscopic Placental Pathology to Clinical Impact-Case Series.

Chronic histiocytic intervillositis (CHI) is a rare placental disorder characterized by an irregular and diffuse infiltration of the intervillous space by a monomorphic population of macrophages and monocytes. CHI is associated with adverse pregnancy outcomes, including intrauterine fetal demise, miscarriage, fetal growth restriction (FGR), and preterm birth. Its etiology remains unknown, and its pathophysiology is not fully understood; however, an underlying immune disorder targeting the semiallogeneic fetus has been proposed. Notably, CHI has undergone changes following the COVID-19 pandemic, now recognized as part of the SARS-CoV-2 placentitis triad. In this case series, we describe two pregnancies affected by CHI, highlighting their clinical relevance due to the immediate neonatal implications and the impact on maternal obstetric prognosis.