Co‑existence of triple‑negative essential thrombocythemia and double transcript chronic myeloid leukemia: A case report.

Chronic myeloproliferative neoplasms (MPN) include polycythemia vera (PV), primary myelofibrosis, essential thrombocythemia (ET) and chronic myeloid leukemia (CML). Overlapping MPNs are rare; however, they can occur in the same individual. The present case report describes a patient with both triple-negative ET and CML. A 64-year-old woman was followed-up at our hematology clinic at Feist Weiller Cancer Center, Louisiana State University Health Shreveport (Shreveport, LA, USA) since 2000 after she was diagnosed with JAK2V617F-negative ET. The patient remained stable on hydroxyurea until 2012, when they underwent a bone marrow biopsy for progressively increasing white blood cell counts, and the pathology was consistent with CML; PCR for BCR-ABL was positive for both P210 and P190 transcripts. The patient was then initiated on dasatinib. After dasatinib, they were given a trial of imatinib, and were later transitioned to nilotinib and finally to bosutinib (2019) due to unchanged thrombocytosis. Next-generation sequencing from a bone marrow biopsy in 2019 demonstrated an EZH2 mutation that may be associated with triple-negative ET. CML was in major molecular response at that time. The patient was continued on bosutinib with hydroxyurea, after which hydroxyurea was changed to anagrelide due to worsening anemia and persistent thrombocytosis. However, bosutinib and anagrelide were discontinued due to worsening pulmonary hypertension. The patient was noted to have peripheral blasts of 14% by flow cytometry, after which they underwent a repeat bone marrow biopsy in 2022, which showed extensive myelofibrosis. BCR-ABL transcripts were undetectable. Given their accelerated myelofibrosis, the patient was started on a hypomethylating agent, decitabine/cedazuridine, along with darbepoetin for anemia in June 2022. Given their persistent thrombocytosis, the patient was also started on peginterferon α. Most studies reporting two clonal processes in the same patient have been for PV and CML. To the best of our knowledge, this is the first reported case of triple-negative ET with double transcript CML in the same individual.