Reversal of FLT3 mutational status and sustained expression of NPM1 mutation in paired presentation, and relapse samples in a patient with acute myeloid leukemia.

We report a case of de novo acute myeloid leukemia (AML) with unstable FLT3 gene mutations and stable NPM1 mutation. FLT3/D835 and NPM1 (Type A) mutations were detected upon diagnosis. During the relapse, the FLT3/D835 mutation changed to an FLT3/ITD mutation while the NPM1 (Type A) mutation was retained. Cytogenetic analyses showed the normal karyotype at diagnosis and relapse. Our findings raise interesting questions about the significance of these mutations in the leukemogenic process, about their stability during the evolution of the disease, and regarding the selection of appropriate molecular markers for the monitoring of minimal residual disease.