The placental lesions in congenital syphilis

Summary Placentas from six mothers with serological tests suggestive of recent syphilitic infection and whose babies were suspected of being or proven to be infected by Treponema pallidum are described. One placenta from this series was large, bulky and pale, while the other 5 were without remarkable gross features. In all cases, the associated histological lesions were 1) hypercellular areas in the terminal and stem villi and 2) a focal peri- and/or intravillous polymorphonuclear concentration with or without necrosis. The former change which was the most frequent was characterized by an apparent increase of villous stromal cells, ultrastructurally indentified as mesenchymal cells and Hofbauer cells. In addition, numerous fetal monocytes were found in the villous vascular lumina. The findings described here and in the literature suggest that congenital syphilis is associated with a spectrum of placental changes. We believe that these changes depend on the immunological reaction of the fetus. According to the sequence of events described in untreated patients, we distinguish two morphological phases: 1) an inductive phase without placental changes and 2) a reactive phase characterized by a predominantly lymphocytic inflammatory infiltration of the villi, followed by a reaction of mononuclear phagocytes.