Histopathological aspects of cardiac biopsy in pediatric patients with dilated cardiomyopathy

Background: Dilated cardiomyopathy (DCM) is a heart muscle disease with cardiac dysfunction and a heterogenous disorder. This disease may show various histopathological aspects of the myocardium, but little is known about these in children. Methods: Histopathological findings of endomyocardial biopsy from 20 pediatric patients with DCM were analyzed and compared with those in adult patients. Results: Advanced histopathology, including myocytolysis and/or fragmentation of muscle bundles, was frequently observed in patients with poor prognosis. Patchy fibrosis was predominantly demonstrated in the pediatric patients, whereas perivascular fibrosis was mostly observed in the older adults. The myocarditic index, assessed in terms of the findings of fibrosis, size variation of myocytes, disarrangement of muscle bundles and mononuclear cell infiltration was higher in the pediatric patients than in the older adults (P < 0.05). Bizarre myocardial hypertrophy with disorganization, which tends to be frequently demonstrated in hypertrophic cardiomyopathy, was revealed in 30% of the pediatric patients, whereas it was disclosed in none of the older adult patients (P < 0.05). Conclusion: These results suggest that the major pathogenetic factors of DCM in children may be different from those in adults.