PDGFRB and primary myelofibrosis: No rearrangement of PDGFRA, PDGFRB, FGFR1, or PCM1-JAK2; the Philadelphia chromosome; or BCR-ABL1 gene fusion should be detected as any diagnostic criteria for polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) [1,5,11,12].