When Pneumonia is Not Pneumonia: Acute Myocarditis Encountered in a Pediatric Emergency Service

Abstract

Pediatric acute myocarditis often presents with dominant respiratory symptoms, creating a significant diagnostic overlap with common lower respiratory tract infections. This clinical mimicry frequently results in misdiagnosis, such as pneumonia, and potentially fatal delays in specialized cardiac care. We report three consecutive male patients (aged 6 months to 3.5 years) initially referred to a Pediatric Pulmonology Service for presumed consolidative pneumonia. The diagnosis was shifted to acute myocarditis only after identifying cardiac “red flags,” including tachycardia disproportionate to fever, cardiomegaly on imaging, and elevated cardiac biomarkers or pericardial effusions. Clinical management included intravenous immunoglobulin, pulse steroids, and supportive therapy. One patient required electrical cardioversion for refractory ventricular tachycardia. All three patients achieved clinical recovery or significant improvement, with normalization of cardiac function or resolution of effusions. Emergency medicine specialists and pediatricians must maintain a high index of suspicion for acute myocarditis in children presenting with respiratory distress. Recognizing clinical findings that are disproportionate to the degree of parenchymal lung involvement is essential to prevent diagnostic delays and ensure the timely initiation of life-saving interventions