Chronic myeloid leukemia in blast phase masquerading as T-lymphoblastic lymphoma with t(22;22) karyotype: a case report.

This article reports a rare case of chronic myeloid leukemia (CML) in blast phase presenting clinically as T-lymphoblastic lymphoma (T-LBL). A 56-year-old male was admitted due to cervical masses, and lymph node biopsy initially diagnosed T-LBL. Subsequent bone marrow examination revealed positivity for the BCR::ABL1 (P210) fusion gene. Flow cytometry (FCM) and immunohistochemistry (IHC) confirmed that the tumor cells co-expressed T-lymphoid and myeloid antigens, and fluorescence in situ hybridization (FISH) detected BCR::ABL1 fusion signals in lymph node tissue, leading to the final diagnosis of de novo blast phase CML (BP-CML) with mixed phenotype (T-lineage and myeloid expression). The chromosomal karyotype evolved from the initial complex karyotype t(22;22) to t(9;22;22), revealing that the Philadelphia (Ph) chromosome translocation was the initiating event of the disease. The patient achieved molecular remission following chemotherapy with the Hyper-CVAD/MA regimen combined with a tyrosine kinase inhibitor (TKI). This case underscores the importance of differentiating BP-CML among adult Ph-positive T-lymphoblastic neoplasms and highlights the value of multi-platform integrated diagnosis for identifying atypical presentations.