Late relapse after allogeneic bone marrow transplantation for Philadelphia-positive acute lymphoblastic leukaemia

Late relapse of leukaemia is rare in patients with chronic myeloid leukaemia (CML) subjected to allogeneic bone marrow transplantation in chronic phase. Herein, we report a patient who presented with acute lymphoblastic leukaemia who after chemotherapy developed a picture consistent with CML in chronic phase. He then received an allograft from an HLA-identical sister and remained in complete remission for 4 years, before he eventually relapsed with features of myeloid transformation of CML. We speculate that the same population of already transformed leukaemic progenitor cells may have given rise to the original lymphoid blast cells and the myeloid blast cells that characterized the terminal relapse.