Extensive Perivillous Fibrin and Intervillous Histiocytosis in a SARS-CoV-2 Infected Placenta From an Uninfected Newborn: A Case Report Including Immunohistochemical Profiling.

Placental infection by SARS-CoV-2 with various pathologic alterations reported. Inflammatory findings, such as extensive perivillous fibrin deposition and intervillous histiocytosis, have been postulated as risk factors for fetal infection by SARS-CoV-2. We describe the placental findings in a case of a 31-year-old mother with SARS-CoV-2 infection who delivered a preterm female neonate who tested negative for SAR-CoV2 infection. Placental examination demonstrated a small for gestational age placenta with extensive intervillous histiocytosis, syncytiotrophoblast karyorrhexis, and diffuse intervillous fibrin deposition. Immunohistochemical staining demonstrated infection of the syncytiotrophoblasts by SARS-CoV-2 inversely related to the presence of intervillous histiocytes and fibrin deposition. Our case demonstrates that despite extensive placental pathology, no fetal transmission of SARS-CoV-2 occurred, as well as postulates a relationship between placental infection, inflammation, and fibrin deposition.