Case Report: Co-existence of gene fusion and variants in myeloid neoplasm with persistent leukocytosis, large splenomegaly, and eosinophilia.

Persistent leukocytosis, massive splenomegaly, and eosinophilia are common manifestations in patients with myeloproliferative neoplasms (MPNs), particularly in those with chronic myeloid leukemia (CML). CML is characterized by the fusion gene, typically associated with the t(9;22)(q34;q11) translocation. Herein, we report a case of myeloid neoplasm with a rare variant translocation, t(4;22)(q12;q11), involving the fusion gene and coexisting variants, accompanied by persistent leukocytosis, massive splenomegaly, and eosinophilia. Laboratory tests showed elevated white blood cell counts, with increased monocytes, neutrophils, and eosinophils. Bone marrow aspiration revealed a granulocytic-erythrocytic ratio of 189:1, marked granulocytic hyperplasia, and numerous immature granulocytes. Genetic testing confirmed an uncommon and coexisting mutations (c.1666G>A and c.1701A>G), confirming the diagnosis of myeloid neoplasm with rearrangement. Treatment with imatinib, a tyrosine kinase inhibitor, resulted in a continuous complete molecular response (CMR). To our knowledge, this is the first report to demonstrate the clinical and cytogenetic manifestations of positive myeloid neoplasm coexisting mutations. Furthermore, it emphasizes the effectiveness of targeted therapy and the significance of personalized management.