An autopsy case of giant cell myocarditis showing shared pathology in the myocardium and skeletal muscles.

• This patient developed severe, lethal cardiogenic shock. • In postmortem analysis, infiltration of giant cells and lymphocytes into both the myocardium and skeletal muscles was documented; therefore, the patient was diagnosed with giant cell myocarditis with polymyositis. • Giant cell myocarditis with polymyositis is typically associated with thymoma and myasthenia gravis; however, in this case, it was not associated with thymoma, and infiltration of giant cells into both cardiac and skeletal muscle is infrequent. [ABSTRACT FROM AUTHOR]