Lymphoid blast crisis of chronic myelogenous leukemia occurring more than 11 years after receiving an allogeneic bone marrow transplant for chronic myelogenous leukemia in myeloid blast crisis at onset.

A 25-year-old male developed lymphoid blast crisis (BC) of chronic myelogenous leukemia (CML) more than 11 years after receiving an allogeneic bone marrow transplant (alloBMT) for CML with myeloid BC at presentation from his HLA-identical brother. The lymphoid BC of CML probably occurred without a preceding chronic phase of CML. This case illustrates the difficulties involved in determining the appropriate length of follow-up after alloBMT.