Patients with Chronic Myeloid Leukemia Diagnosed with Predominant Thrombocytosis without Marked Leukocytosis: Case Series

Chronic myeloid leukemia (CML) is a clonal hematopoietic pluripotent stem cell disease characterized by excessive and uncontrolled proliferation of myeloid lineage cells. Platelet count is increased in more than half of patients and the appearance of platelets is variable. When patients present with predominant thrombocytosis without marked leukocytosis, they should be tested for the Philadelphia chromosome or (breakpoint cluster region- Abelson) BCR-ABL to distinguish cases of CML. In this study, the data of 215 patients diagnosed with CML between 2010 and 2023 were retrospectively evaluated. The study enrolled patients aged ≥18 years with leukocyte count <40 x109/L and platelet count >500 x109/L at the time of diagnosis. While investigating the etiology of predominant thrombocytosis and no significant leukocytosis, 13 patients diagnosed with CML were identified. The proportion of these patients among all patients with CML was 6%. This study showed that CML should be considered in the differential diagnosis of patients with predominant thrombocytosis without marked leukocytosis. In these patients, the Ph chromosome should definitely be checked before ET is diagnosed. Making a correct diagnosis in this patient group is important in order to start tyrosine kinase inhibitor treatment before it progresses to accelerated or blastic phases.