Chronic inflammatory lesions of the placenta.

The chronic inflammatory lesions of the placenta often run in the shadows of the better-known acute inflammatory processes of the placenta, such as acute chorioamnionitis and acute funisitis. A heterogeneous population of T-cell lymphocytes, plasma cells, and macrophages is the primary player in chronic villitis, chronic chorioamnionitis, chronic deciduitis, and chronic intervillositis, and eosinophils are an added component of eosinophilic/T-cell chorionic vasculitis. The histologic appearance, sites of occurrence in the placenta, and pathogeneses of these entities are reviewed.