Myeloproliferative hypereosinophilic syndrome presenting as cardiac failure and response to imatinib.

Idiopathic hypereosinophilic syndrome was first defined by Chursid et al in 1975; however, following the advances in molecular biology, the World Health Organization has proposed a classification in 2008. Hypereosinophilic syndrome is a heterogeneous group of uncommon disorders characterized by marked peripheral eosinophilia and end-organ manifestation. The authors describe a case of sudden-onset cardiac failure in a young individual who had marked peripheral eosinophilia and detection of FIP1L1/PDGFRA fusion gene. A diagnosis of myeloproliferative neoplasm with eosinophilia and eosinophilic endocarditis was made. His clinical and laboratory parameters showed a dramatic response to imatinib and prednisone.