Value and limitations of targeted next-generation sequencing in idiopathic hypereosinophilia: an integrative diagnostic tool in challenging cases

Here, we reviewed clinical-morphological data and investigated mutational profiles by NGS in a single-center series of 28 consecutive patients admitted to our hospital between September 2011 and November 2021 for idiopathic hypereosinophilia (HE). Bone marrow (BM) morphology was evaluated in 22 patients: while in six subjects BM was unremarkable, in the remaining cases an increase in BM eosinophils was observed, together with a slight increase in BM fibrosis (MF-1) in 5/22 patients. A total of 4/28 patients had at least one genetic lesion by targeted NGS. In particular, the genes involved were: two each of TET2 and DNMT3A; and one each of JAK2V617F, ASXL1, PPM1D, and ZBTB33. Notably, JAK2V617F and TET2 mutations co-occurred, with the JAK2V617F-mutated sample also carrying TET2 lesions. Median VAF was 21