Recent studies on hematological malignancies have reported that the overexpression or downregulation of S100A8 and S100A9 is associated with acute myeloid leukemia (AML), chronic lymphoid leukemia (CLL), and myeloproliferative diseases (12–14) However, the function of S100A8 and S100A9 in chronic eosinophilic leukemia is not fully understood. The gene discussed is S100A8; the disease is Chronic Eosinophilic Leukemia, Not Otherwise Specified.