BACKGROUND: Myocarditis is a rare but potentially fatal complication of mumps virus infection. Left ventricular non-compaction (LVNC) is a rare congenital abnormality that can lead to development of low cardiac output, cardiac dysfunction, arrhythmias, or sudden cardiac death. To the best of our knowledge, no autopsy cases of mumps myocarditis with LVNC have been reported in the literature. Here, we report an autopsy case of a 21-month-old girl who died due to mumps myocarditis associated with an undiagnosed LVNC.

CASE REPORT: Postmortem computed tomography demonstrated bilaterally enlarged parotid glands. Serum analysis of anti-mumps IgM titer was positive. Macroscopic and histological examinations revealed glandular destruction with massive inflammatory cell infiltration of the enlarged parotid glands and mild inflammatory cell infiltration of the heart, which showed prominent trabeculations and deep intra-trabecular recesses, indicating LVNC. Immunohistochemical analyses showed positive immunostainings for mumps in the cardiac and salivary gland tissues.

CONCLUSIONS: These findings suggest that mumps myocarditis associated with LVNC contributed to this patient’s death. Myocarditis patients with other comorbidities, including LVNC, may be at higher risk of sudden death. Further reports of mumps myocarditis and LVNC are needed to better understand the mechanisms of sudden unexpected deaths in children.

Keywords: Autopsy, Comorbidity, Death, Sudden, Heart Defects, Congenital, Pediatrics, Vaccination, Death, Sudden, Cardiac, Fatal Outcome, Infant, mumps, myocarditis