Eosinophilia, basophilia and mastocytosis in a case of myeloproliferative neoplasm with very low bcrabl1 transcript: To be or not to be cml

Aims & Objectives: Basophilia and eosinophilia are common manifestations of chronic myeloid leukemia (CML) The diagnosis is usually established by demonstrating the presence of BCR-ABL1 fusion transcript The presence of numerous mast cells in such scenario is very uncommon and should prompt further evaluation for systemic mastocytosis associated with myeloid or lymphoid hematologic diseases (SM-AHNMD) Here we report an unusual case of myeloproliferative neoplasm (MPN), which showed abundance of morphologically and immunophenotypically abnormal mast cells, thus confirming to the diagnosis of systemic mastocytosis with associated MPN, possibly chronic myeloid leukemia Interestingly, the diagnostic sample showed a very low BCR-ABL1 transcript level Patients/Materials & Methods: A 66-year old male presented with a history of weight loss and mild splenomegaly of 1 month duration Complete hemogram showed Hb of 5 9, TLC of 17,000/cumm and platelet count of 16,000/cumm Bone marrow (BM) examination was performed and subjected to flow cytometry and molecular analysis Results: Peripheral smear examination showed marked eosinophilia (57%) and basophilia (10%) with absence of any shift cells, blasts or dyspoiesis Bone marrow examination revealed marked proliferation of eosinophils (21%) and basophils (4%) with no excess of blasts First round of Nested RT-PCR for BCR-ABL transcript (qualitative) analysis did not revealed any band;however second round revealed BCR-ABL1 p210 (e13a2) transcript band The patient failed to respond to Imatinib A repeat BM examination, performed after 2 months showed persistence of the findings with prominent basophilia (14%) and no evidence of blast excess However, the bone marrow biopsy showed aggregates of mast cells An aberrant expression of CD25 on the mast cells was elicited on flow cytometry Sample subjected for comprehensive NGS panel for myeloid neoplasms was negative for commonly known genetic aberrations including PDGFR-A, PDGFR-B, FGFR-1, KIT and JAK-2 Thus a diagnosis of systemic mastocytosis associated with myeloid diseases possibly CML was conferred In view of inadequate response to imatinib, the patient was started on Dasatinib Unfortunately the patient had a rapid downhill course, developed COVID and succumbed to death Discussion & Conclusion: A diagnostic dilemma, presence of abnormal population of mast cells and a very low level of BCR-ABL1 transcript level will be discussed