CD8+ T-lymphocytes infiltrate the myocardium in fulminant herpes virus myocarditis.

We report two cases of fulminant viral myocarditis in previously healthy children. They were caused by herpes simplex virus (HSV)-I (in a boy aged 3 years) and Epstein-Barr virus (EBV) (in a boy aged 12 months). We obtained the diagnosis of HSV-l myocarditis by immunohistochemistry and the diagnosis of EBV myocarditis by in situ hybridization. Histologic examination of heart tissue from the two boys revealed mononuclear cell infiltration of the myocardium. Immunohistochemical staining identified these cells as CD8+ T-lymphocyles. CD8+ T-lymphocytes induced by herpes virus infections may play an important role in the damage to heart muscle fibers seen in fulminant myocarditis in previously healthy children. To our knowledge, this is the first report of HSV-l or EBV myocarditis (at least in children) in which viral infection has been demonstrated in the myocardium.