A 14-year-old girl presented with myalgias and decreased energy and was found to have a white count of 73 000 with 75% eosinophils. Flow cytometry and immunostains showed the blasts in the bone marrow expressed both myeloid and lymphoid markers. Patient was diagnosed with acute multilineage (B/Myeloid) leukemia. Genetic testing revealed four copies of the RUNX1 gene region in 25.5%, with a normal karyotype and no evidence of t(8;21) or t(12;21) by fluorescence in situ hybridization. RUNX1 translocations and amplifications have been implicated in acute myeloblastic leukemia, acute lymphoblastic leukemia, and MDS, but have not yet been seen with acute multilineage leukemia. Additionally, it is unclear what the risk stratification of this unique presentation will turn out to be.
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