Multisystem inflammatory syndrome and lymphohistiocytic myocarditis after Covid‐19 vaccine in a middle‐aged woman

We describe a 51‐year‐old otherwise healthy woman hospitalized for hypotension, fever, and weakness 4 days after the second‐dose Covid‐19 mRNA vaccine. Elevated inflammatory markers, natriuretic peptide levels and troponin levels, and slightly reduced left ventricular ejection fraction of 50% were noted. We also found the multiple organ damage, including mucocutaneous, gastrointestinal, and neurologic systems. In addition, we revealed the positive results for anti‐nucleocapsid SARS‐CoV‐2 IgG, albeit negative for SARS‐CoV‐2 polymerase chain reaction testing, suggesting the prior asymptomatic Covid‐19 infection. We finally diagnosed her as multisystem inflammatory syndrome after vaccination. Of note, we obtained myocardial specimen from the patients and demonstrated the lymphohistiocytic myocarditis, which is a rare form of myocarditis.