Myeloid neoplasms accompanied by HE (HEN) include the rare variant of acute eosinophilic leukemia, the more common chronic form of eosinophilic leukemia (CEL) that is often associated with the FIP1L1-PDGFRA rearrangement and endomyocardial thrombosis/fibrosis (HESN), and other myeloid neoplasms with rearrangements involving PDGFRA, PDGFRB, or FGFR1, such as the 8p11 syndrome [8-18,28-30]. The gene discussed is FGFR1; the disease is Chronic Eosinophilic Leukemia, Not Otherwise Specified.