JAK2 and myeloproliferative disorder: It is worth noting that a diagnosis of MPN-U cannot be made in cases with genetic lesions defining other myeloid neoplasms (BCR-ABL1 fusion, rearrangements of PDGFRA, PDGFRB, FGFR1 and/or PCM1-JAK2 fusion), if clinical data are incomplete or if biopsy samples are inadequate [1,33].