Eosinophilic myocarditis temporally associated with conjugate meningococcal C and hepatitis B vaccines in children.

We report the first cases of tissue-proven eosinophilic myocarditis after single vaccine administration of conjugate meningococcal C and hepatitis B vaccine, respectively. The nature of histopathologic findings strongly supports hypersensitivity reaction and negates viral etiology, which is typically characterized by a lymphocytic infiltrate. Both episodes resolved with corticosteroid therapy. To enhance discussion of our cases, we performed a systematic review of the literature on postimmunization myocarditis or pericarditis, and identified 37 publications, reporting 269 cases during the search period (1966-2007). Time of onset of cardiac symptoms in all patients ranged from 1 to 30 days postimmunization.