A 39 year-old woman with acute myeloid leukemia…Interphase fluorescence in situ hybridization (FISH) suggested a possible fusion between chromosomes 15 and 17 on der(17), but was most consistent with an RARA-PML fusion, not the pathogenic PML-RARA fusion characteristic of M3 AML...She started induction chemotherapy with ATRA, cytarabine and idarubicin. However, her metaphase cytogenetics (46, XX, del(9)(q12q32), del(12)(q12q21)[6]/idem, −6, −16, add(16)(p13.2), +2 mar[13]/46, XX[1], Figure 1C and D) revealed a complex pattern, which is associated with < 15% long-term survival, and is treated with allogeneic transplant in first remission whenever possible....Further, because her complex cytogenetics predicted an unfavorable prognosis, it was essential to determine whether the patient had a recognized PML-RARA fusion gene (since t(15;17) supercedes other cytogenetic findings and predicts a favorable outcome in patients treated with ATRA).