Myeloid sarcoma as EM blast crisis in BCR-ABL1 e6a2+ CML with myelofibrosis and TB: a case report.

BCR-ABL1 e6a2-positive chronic myeloid leukemia (CML) is a rare molecular subtype of CML, accounting for less than 1 % of CML cases. It was shown to be associated with aggressive clinical behavior and a tendency toward disease progression. Here, we report a 56-year-old man who presented with pancytopenia, cervical lymphadenopathy, and severe myelofibrosis, without the typical leukocytosis observed in classic CML. Concurrent active pulmonary tuberculosis further complicated the diagnostic process. Hyperuricemia and elevated levels of lactate dehydrogenase (LDH) suggested a high cell-turnover state, and cervical lymph node biopsy confirmed myeloid sarcoma. Cytogenetic analysis revealed t(9;22)(q34;q11.2) with trisomy 8. Real-time quantitative polymerase chain reaction (RT-qPCR) identified the rare BCR-ABL1 e6a2 transcript. The patient received second- and third-generation tyrosine kinase inhibitor (TKI)-based therapy combined with chemotherapy. An individualized rifamycin-sparing anti-tuberculosis regimen was also prescribed. The patient achieved complete remission with marked regression of myelofibrosis. This case suggests that e6a2-positive CML may present with atypical features, including pancytopenia, severe myelofibrosis, and extramedullary blast crisis. In patients with concurrent tuberculosis, timely tissue biopsy and molecular testing are essential to accelerate diagnosis.