Table 2.
Histopathology and immunohistochemistry findings in placental and fetal tissues of the three cases with confirmed SARS-CoV-2 infection during pregnancy.
| Case | Placental macroscopic fetaures | Placental microscopic features | SARS-CoV-2 RT-PCR ** | SARS-CoV-2 IHC |
|---|---|---|---|---|
| 1 | Weight*: 550 g (75th percentile). Placental disc measurements: 18.5 × 15 cm. Presence of multiple intraparenchymal hematomas (hemorrhagic areas) compromising 30% of the placental disc. | -Chorioamniotic membranes with predominantly neutrophilic inflammation. Chorioamniotic junction band with lamellar necrosis and transfer of neutrophils to the amniotic epithelium. -Villous sclerosis foci, hemorrhagic infarcts with excess in perivillous fibrin deposits, obliteration, and vascular occlusion of fetal vessels. -Mild acute intervillitis with accumulation of polymorphonuclear neutrophils and area of acute infarction. -The maternal side shows hematic dissection and endovascular thrombi. |
Positive in placental tissue | Positive in trophoblast cells of the chorionic villus. |
| 2 | NA | -Placenta with a maturation pattern consistent with the second trimester with excess perivillous fibrin deposits and Hofbauer cell hyperplasia. -Acute placental infarction with a 30% extension, presence of focal ischemic changes. -Moderate (grade II) chronic lymphoplasmacytic villitis. | Positive in placental tissue and umbilical cord Negative in fetal heart and lung tissue |
Positive in mesenchymal and endothelial cells of the chorionic villi. Positive staining in some mesenchymal cells of the umbilical cord. |
| 3 | Weight*: 432 g (25th percentile) | -Placenta with a maturation pattern consistent with the third trimester, excess perivillous fibrin deposits and Hofbauer cell hyperplasia. -Acute placental infarction with extension of approximately 30%. - Hyperplasia of syncytial cell knots. | Positive in placental tissue | Positive in mesenchymal and endothelial cells of the chorionic villi. Positive staining in some syncytial cells. |
NA: Not available. RT-PCR: reverse transcription polymerase chain reaction. IHC: immunohistochemistry.
*Placental weight percentiles calculated according to Raymond et al (2018). **Viral genome sequencing could not be performed on any of the FFPE samples due to fixation and subsequent nucleic acid degradation, resulting in fragmented RNA transcripts that were inadequate to obtain appropriate sequencing results.