[Successful management of splenomegaly with ruxolitinib prior to allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia transformed from post-polycythemia vera myelofibrosis].

A 64-year-old woman was admitted to our hospital to undergo allogeneic stem cell transplantation. She was diagnosed with polycythemia vera with a JAK2 V617F mutation 7 years ago. She was administered ruxolitinib for splenomegaly two years prior to admission but this was discontinued because of progressive pancytopenia. One months after cessation of ruxolitinib, she developed acute myeloid leukemia transformed from post-polycythemia vera myelofibrosis. Although she achieved complete remission after induction therapy, 8-finger-breadth splenomegaly remained below the left costal margin. Ruxolitinib was re-administered following two courses of consolidation therapy. She underwent unrelated peripheral blood stem cell transplantation. Ruxolitinib was administered until the day before transplantation, and the spleen was palpated in 4-finger breadth below costal arc. Neutrophil engraftment was achieved 13 days after transplantation. In allogeneic stem cell transplantation, splenomegaly is one of the risk factors for engraftment failure and/or therapy-related mortality. Hence, a smaller spleen size can theoretically improve the outcome after transplantation. The administration of ruxolitinib prior to transplantation may have contributed to engraftment with a non-invasive reduction in the size of the spleen.