[Acute myelogenous leukemia with ins(21;8) expressing AML-1-MTG8 fusion transcript]

Here we report a case of acute myelogenous leukemia (M2, FAB classification) presenting with cytogenetic abnormalities of ins(21;8), +del(8) without t(8;21). A 8;21 chromosome translocation is frequently found in acute myelogenous leukemia, especially in the M2 subtype. The translocation results in a fusion transcript between AML1 and MTG8 (ETO), assigned on chromosomes 21 and 8, respectively. Among patients with a t(8;21) abnormality, solid leukemic tumor deposits outside the marrow or good response to chemotherapy are observed frequently. Decrease in neutrophil alkaline phosphatase score and positive rate, and eosinophilia in bone marrow or the blast cells with Auer rods expressing CD19, CD56 antigens occur at a relatively high rate. Although our case lacked these clinical, cytological and cytochemical features, expression of chimeric AML1-MTG8 mRNA was detected. AML1-MTG8 fusion transcript may play a critical role in leukemogenesis of AML M2. Studies on this case may help to reveal the oncogenic function of the AML1-MTG8 fusion gene in AML M2.