Eosinophilic myocarditis is a rare disease occurring mainly in adulthood. It is generally known to be caused by autoimmune diseases, parasitic infections, hypersensitivity to drugs or substances, and after vaccinations. We describe the case of a 15-year-old adolescent, who presented initially with flu-like symptoms, as well as syncope. Subsequently, catecholaminergic treatment had to be initialised because of cardiac failure. Peripheral eosinophil count was normal at admission and at the time of endomyocardial biopsy. The biopsy, however, proved the diagnosis of eosinophilic myocarditis, but the causative agent remained unclear despite intensive diagnostic work-up. Cardiac magnetic resonance imaging showed signs of acute myocardial oedema and a delayed enhancement in the basal inferolateral segments consistent with acute myocarditis. Under treatment with corticosteroids, angiotensin-converting enzyme inhibitor, and warfarin, we accomplished a rapid and complete recovery of cardiac function and histology. This unique case of eosinophilic myocarditis is rare in childhood. The differential diagnosis and diagnostic pathway is discussed, and a review of the literature and therapeutic options based on the literature is performed.
