Rapid development of acute monocytic leukemia (AML-M5b) with t(9;11)(p22;q23) after chemotherapy for T-cell...

To investigate the diagnosis and treatment of T lymphoblastic lymphoma (T-LBL) progressing into acute monocytic leukemia (AML-M5b) and explore possible pathogenic mechanisms.

Comprehensive diagnosis and evaluation of the patient's disease status were conducted through lymph node biopsy, bone marrow aspiration and biopsy, PET/CT, immunohistochemistry, flow cytometry, fusion gene detection, and whole-exome sequencing (WES) based on the clinical manifestations at different stages.

The lymph node biopsy revealed Ki67 positivity at 80 % and expression of TDT, CD4, CD8, CD3, and CD5. The PET/CT scan showed increased FDG metabolism at multiple sites. Based on relevant tests and examination results, the patient was diagnosed with T-LBL (stage IV; IPI score, 3). After three cycles of chemotherapy, abnormal immature monocytes were detected using bone marrow flow cytometry, suggesting an acute progression from T-LBL to AML-M5b. Chromosomal karyotype analysis revealed t(9; 11)(p22; q23) and the MLL-AF9 fusion gene. WES analysis identified mutations in several genes, among which mutations in SET domain-containing protein 2 and CBL may be associated with the occurrence of acute myeloid leukemia. The patient died 1 month after AML-M5b diagnosis.

Patients with T-LBL progression to AML have a poor prognosis and shorter overall survival. Hence, exploring the pathogenic mechanisms and reasons for disease progression has significant implications for finding effective treatment modalities and prolonging patient survival.