Histopathological findings of pericarditis in a patient with multisystem inflammatory syndrome in children associated with COVID‐19: A case report

Multisystem inflammatory syndrome in children (MIS‐C), which is associated with the novel coronavirus disease 2019 (COVID‐19), has been described as an inflammatory complication of exposure to the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). It carries a risk of serious and lethal complications, including cardiogenic shock. Here, we report the pathological findings of the pericardium in a 10‐year‐old child with MIS‐C, who developed pericarditis‐induced cardiac tamponade. In the patient's pericardium, the numbers of infiltrating CD68(+) macrophages; CD3(+), CD4(+), and CD8(+) T cells; and myeloperoxidase(+) granulocytes were increased, although the number of CD20(+) B cells was not. These findings provide a clue to understanding the pathophysiology of MIS‐C.