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Hofbauer Cells and COVID-19 in Pregnancy.

Authors :: Schwartz DA
Baldewijns M
Benachi A
Bugatti M
Bulfamante G
Cheng K
Collins RRJ
Debelenko L
De Luca D
Facchetti F
Fitzgerald B
Levitan D
Linn RL
Marcelis L
Morotti D
Morotti R
Patanè L
Prevot S
Pulinx B
Saad AG
Schoenmakers S
Strybol D
Thomas K
Tosi D
Toto V
van der Meeren LE
Verdijk RM
Vivanti AJ
Zaigham M
Source :: Archives of pathology & laboratory medicine [Arch Pathol Lab Med] 2021 Nov 01; Vol. 145 (11), pp. 1328-1340.
Publication Year :: 2021
Abstract: Context.—: SARS-CoV-2 can undergo maternal-fetal transmission, heightening interest in the placental pathology findings from this infection. Transplacental SARS-CoV-2 transmission is typically accompanied by chronic histiocytic intervillositis together with necrosis and positivity of syncytiotrophoblast for SARS-CoV-2. Hofbauer cells are placental macrophages that have been involved in viral diseases, including HIV and Zika virus, but their involvement in SARS-CoV-2 is unknown.<br />Objective.—: To determine whether SARS-CoV-2 can extend beyond the syncytiotrophoblast to enter Hofbauer cells, endothelium, and other villous stromal cells in infected placentas of liveborn and stillborn infants.<br />Design.—: Case-based retrospective analysis by 29 perinatal and molecular pathology specialists of placental findings from a preselected cohort of 22 SARS-CoV-2-infected placentas delivered to pregnant women testing positive for SARS-CoV-2 from 7 countries. Molecular pathology methods were used to investigate viral involvement of Hofbauer cells, villous capillary endothelium, syncytiotrophoblast, and other fetal-derived cells.<br />Results.—: Chronic histiocytic intervillositis and trophoblast necrosis were present in all 22 placentas (100%). SARS-CoV-2 was identified in Hofbauer cells from 4 of 22 placentas (18.2%). Villous capillary endothelial staining was positive in 2 of 22 cases (9.1%), both of which also had viral positivity in Hofbauer cells. Syncytiotrophoblast staining occurred in 21 of 22 placentas (95.5%). Hofbauer cell hyperplasia was present in 3 of 22 placentas (13.6%). In the 7 cases having documented transplacental infection of the fetus, 2 (28.6%) occurred in placentas with Hofbauer cell staining positive for SARS-CoV-2.<br />Conclusions.—: SARS-CoV-2 can extend beyond the trophoblast into the villous stroma, involving Hofbauer cells and capillary endothelial cells, in a small number of infected placentas. Most cases of SARS-CoV-2 transplacental fetal infection occur without Hofbauer cell involvement.