BCR and histiocytic sarcoma: In addition to CML, the BCR-ABL1 fusion has also been identified in a subset of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) cases, as well as in rare instances of other hematological malignancies, including lymphoma, histiocytic sarcoma, and myeloid sarcoma, suggesting potential clonal relationships among different types of hematological tumors (10–14).