[Chronic myeloid leukemia presenting as B-lymphoblastic transformation after treatment for mucinous adenocarcinoma of...

Secondary leukemia often occurs as acute myeloid leukemia (AML) and myelodysplastic neoplasms (MDS), but is rare in chronic myeloid leukemia (CML). A 50-year-old man was diagnosed with secondary CML in B-lymphoid blast phase 12 years after the onset of mucinous gland carcinoma of unknown origin. After resection of the carcinoma, he received chemotherapy and radiotherapy. He achieved a major molecular response with tyrosine kinase inhibitor and hyper CVAD/MA therapy, followed by allogeneic hematopoietic stem cell transplantation in deep molecular response (DMR) approximately 1 year after the start of treatment. Twenty-six months later, he continues to maintain DMR under treatment with asciminib. Although the development of secondary CML is very rare, CML incidence is higher in patients with a history of cancer treatment. Consequently, it is important to be aware the risk of not only MDS/AML but also CML in this group.