Sudden cardiac death due to giant cell inflammatory processes.

Granulomatous inflammation of the myocardium may occur in a number of systemic disease processes including those with infectious etiologies such as fungal, mycobacterial and parasitic infections, as well as hypersensitivity reactions, and rarely autoimmune disorders. In many of these disorders, giant cells are components of the inflammatory infiltrate. Systemic granulomatous processes of unknown pathogenesis, most notably sarcoidosis, may also be associated with involvement of the myocardium. Occasionally, these disorders are associated with sudden death due to pathologic involvement of the heart. In contrast, giant cell myocarditis, also known as idiopathic myocarditis, a rare, frequently fulminant and fatal disorder of unknown etiology, is isolated to the heart and lacks systemic involvement. This disorder is most commonly diagnosed at autopsy. We present two cases in which sudden death resulted from a giant cell inflammatory process affecting the myocardium. Both individuals lacked antemortem diagnoses and collapsed at their respective places of employment. These cases compare and contrast the clinical and pathologic issues involved in the differential diagnoses of the subgroup of sudden cardiac deaths resulting from giant cell inflammatory processes that affect the myocardium, as well as the value of histologic examination and immunohistochemical studies.