ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Given the proportion of cells positive for BCR/ABL1 fusion, myeloid predominance, and smaller fraction of T lymphoblasts, diagnosis of T‐lymphoblastic transformation in the background of chronic myeloid leukemia (CML) is favored rather than de novo T‐cell acute lymphoblastic leukemia (T‐ALL) or mixed phenotype acute leukemia with t(9;22).