Idiopathic hypereosinophilic syndrome: a case evolving in B-lymphoblastic lymphoma

Idiopathic hypereosinophilic syndrome (HES) is a rare disease characterized by tissue involvement and organ dysfunction due to abnormal eosinophil proliferation. Evolution of HES into myeloid or T-cell malignancies has been frequently reported. Here, we describe a case of HES that preceded the occurrence of a high-grade B-lymphoblastic lymphoma in which clonal evolution has been demonstrated at the molecular level.