LAUSR

Acute myeloid leukemia (AML) with inv(16) is primarily associated with the eosinophilic LAM4 form belonging to the favorable prognosis group of AML. We report the case of an 18-year-old man with acute myeloid leukemia with unusual inversion of chromosome 16. Cytological, phenotypic and cytogenetic investigations showed a divergence from those in the literature. Indeed, the myelogram shows a medullary infiltration by elements blocked at the stage of myeloblates/promyelocytes, containing Auer rods grouped sometimes in fagots in blasts, promyelocytes and neutrophils. In view of this pathognomonic aspect, the diagnosis of AML type M3 is mentioned but quickly questioned by the results of immunophenotyping in favor of a maturing AML (M2). The karyotype and the FISH later objectify a recurrent anomaly "cytologically unexpected" inversion 16 (p13, q22) associated with trisomy 22.