BACKGROUND: Acute myeloid leukemia (AML) with the t(8
21)(q22
q22) mutation, which produces the AML1/ETO fusion gene on chromosome 8q22, is a specific subtype of AML categorized as AML t(8
21) in the WHO classification and AML-M2 in the FAB classification. This subtype is typically linked to a positive prognosis, although variant additional chromosomal abnormalities are often observed. METHODS: We report a rare case of this category with unusual karyotype and morphologic characteristic mimick-ing APL. RESULTS: A diagnosis of acute myeloid leukemia (AML-M2) was made through comprehensive diagnostics. CONCLUSIONS: Recognition of the morphological variation is helpful in diagnosis. In addition, further research is needed to better understand the molecular mechanisms underlying unusual rearrangements and their clinical significance.