Coronary vasospasm in a patient with RUNX1 mutation in eosinophilic leukemia and hypereosinophilic syndrome: A case report.

Hypereosinophilic syndrome (HES) is characterized by persistent eosinophilia and the potential for significant organ damage. Cardiac involvement, a frequent complication, may be life-threatening. We describe the case of a 29-year-old male who presented with chest pain and dyspnea and was found to have eosinophilia. A comprehensive workup, including extensive laboratory and imaging studies, bone marrow aspirate and trephine with cytogenetic testing failed to identify a cause for the HES. Thus, the patient was provisionally diagnosed with idiopathic HES and treated with steroids. Although cytogenetic chromosomal analysis and fluorescence in situ hybridization for myeloid genes were negative, next generation sequencing (NGS) revealed a likely pathogenic variant in RUNX1 consistent with myeloid leukemia. RUNX1 also regulates adverse cardiac remodeling after myocardial infarction. Thus, this case highlights the importance of thorough investigation to determine the etiology of HES and the need to define the role of RUNX1 mutations. Early recognition and prompt initiation of appropriate therapy is crucial for mitigating organ damage and improving patient outcomes. When the diagnosis is uncertain, corticosteroids can be used to control eosinophilia which may be lifesaving. Yet, this case underscores the importance of a comprehensive diagnostic approach, including NGS, in patients with unexplained eosinophilia and cardiac involvement. Learning objectives: Hypereosinophilic syndrome should be considered in patients with unexplained eosinophilia and systemic symptoms.Eosinophilic myocarditis may mimic acute coronary syndromes and can coexist with coronary vasospasm.Early corticosteroid therapy can prevent irreversible organ damage. Comprehensive evaluation is necessary to exclude secondary causes of eosinophilia.Detection of somatic mutations such as RUNX1 may indicate an underlying clonal eosinophilic disorder and warrants hematology input and long-term monitoring.Multidisciplinary care, including cardiology and hematology input, is vital for optimal management.