Case report: Acute lymphoblastic leukemia presenting as myocarditis

Background: Myocarditis develops for a variety of reasons, the most common being viral. An uncommon cause of myocarditis is eosinophilia. Eosinophilia significant enough to cause heart damage is relatively rare. Treatment for eosinophilia varies widely depending on the etiology. Malignancy is a rare cause of eosinophilia. Case presentation: Here, we describe a patient who presented in heart failure secondary to eosinophilic myocarditis, whose eosinophilia was discovered to be secondary to pre-B cell acute lymphoid leukemia with a t(5;14) IL3/IgH rearrangement, which places an enhancer gene from chromosome 14 (IgH) next to IL-3 gene on chromosome 5, which in turn triggers eosinophil production. The patient was treated with standard chemotherapy with daunorubicin and vincristine, and his cardiac function improved on serial echocardiograms. Conclusions: Eosinophilic myocarditis is very rare and requires a thorough workup to identify the etiology of eosinophilia. Eosinophilia due to malignancy is exceedingly rare but important to keep in mind in evaluating children with myocarditis. Keywords: B-cell acute lymphoblastic leukemia; Case report; Eosinophilia; Myocarditi