ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Moreover, in 1/2 cases with PMF histology obvious after TKI, the presence of fibrosis at initial CML diagnosis could have been a possible clue for PMF, although fibrosis alone is not sufficient for PMF diagnosis as fibrosis may be found even in CML; in this case, BCR::ABL1 and JAK2 were both present from initial CML diagnosis, however PMF features became obvious after CMR of CML (4).