“Chronic myelogenous leukemia in primary blast crisis” rather than “de novo BCR‐ABL1‐positive acute myeloid leukemia”

Differentiating chronic myelogenous leukemia in primary blast crisis (CML‐BC) from de novo BCR‐ABL1‐positive acute myeloid leukemia (AML) is a diagnostic challenge with therapeutic consequences. In our case, a basophilia, the presence of the Philadelphia chromosome in all metaphases and the strict exclusion of molecular hallmarks of AML lead us to retain the diagnosis of CML‐BC rather than BCR‐ABL1+ AML.