BACKGROUND: This case report describes a rare presentation of rippling muscle disease (RMD) due to a pathogenic CAV3 variant, manifesting with myocarditis-like cardiac involvement in an adolescent patient. To the best of our knowledge, this represents an exceedingly rare pediatric case of RMD associated with clinically significant cardiac findings. CASE PRESENTATION: A previously healthy 15-year-old male adolescent presented with vomiting and markedly elevated creatine kinase and troponin levels, raising suspicion of acute myocarditis. Cardiac magnetic resonance imaging (MRI) demonstrated non-ischemic myocardial fibrosis, and genetic testing identified a pathogenic de novo variant in the CAV3 gene consistent with rippling muscle disease. CONCLUSIONS: This case highlights the potential for myocarditis-like cardiac involvement in caveolin-3-related rippling muscle disease and underscores the importance of considering underlying genetic myopathies in adolescents presenting with unexplained elevations of serum creatine kinase (hyperCKemia) and cardiac biomarkers.