Coexistent BCR-ABL1 and JAK2 V617F: Converting CML dwarves to et staghorns with imatinib therapy

摘要

The coccurrence of BCR-ABL1 translocation and JAK2 V617F mutations are very rare, with fewer than 50 cases reported in the literature. Clinical and morphologic phenotypes may resemble one myeloproliferative neoplasm (MPN) rather than the other, and in some cases patients do not display features of a JAK2 V617F-positive MPN until after treatment with imatinib. It is unclear whether the JAK2 and BCR-ABL1 alterations exist in the same clone or in competing clones, though a few studies support both possibilities. In the present case, there was a decrease (from 95% to 10%) in the quantity of cells harboring t(9;22) after treatment. Conversely, there was an impression of an increase in the relative percentage of the mutated JAK2 allele. These findings argue for the presence of 2 separate clones (one CML, the other ET) in this case, rather than a common clone harboring both genetic aberrations.