Phenotypic conversion of T-lineage lymphoblasts in the lymph node to myeloblasts in the bone marrow during relapse after allogeneic bone marrow transplantation

The phenotypic conversion of leukemic cells has rarely been reported [1]. I t occurs most often in childhood acute lymphoblastic leukemia (ALL) and in mixed-lineage leukemia [2]. We report a lineage switch of T-lineage ALL to acute myeloblastic leukemia (AML) after an allogeneic bone marrow transplan tation (BMT). In the early stage of relapse, after an allogeneic BMT, the p henotype of leukemic cells in the lymph node was T-lymphoid; after chemothe rapy, that of the cells in the bone marrow converted to myeloid.