Other pulmonary pathology
The DAD pathology in the exudative phase, hyaline membrane formation
inside of the alveolar lumen, was seen, but focal (Figure 4c). The
end-stage pathology of DAD was also present in the hemorrhagic lesion,
accompanying squamous metaplasia (Figure 5c). Although previous autopsy
reports described the DAD pathology is the major cause of lung
failure1, 11, it was minimum in the present case.
Infiltration of neutrophils and lymphocytes were also hardly seen, and
only macrophages predominantly appeared. Immunohistochemistry in use of
anti-SARS-CoV-2 antibody did not reveal any infected cells. Although PCR
showed the viral RNA presence in the nasopharyngeal swab, the
discrepancy would be due to the detection sensitivity. Thus, even if the
virus was present, its copy number would be low.