Although both cases did not have a history of CML, both cases represented T-lymphoblastic CML-BP with unusual features: Case 1 is unusual in that it presented as T-ALL with some CML morphologic feature but never showed CML-CP in her subsequent marrows biopsies; Case 2 is the first reported case of T-lymphoblastic CML-BP harboring BCR-ABL1 transcript with a minor breakpoint. This evidence concerns the gene ABL1 and acute lymphoblastic leukemia.