Report of 3 Cases of Chronic Myelogenous Leukemia with Thrombocythemic Onset

Background : Differential diagnosis may be difficult between essential thrombocythemia (ET) and chronic myelogenous leukemia (CML) with marked thrombocytosis, mild leukocytosis, and a few immature myeloid cells in peripheral blood at onset. The aim of the present study was to analyze clinical, hematologic, and molecular features of patients with CML, mimicking ET. Methods : Among patients from Ewha and Gachon Gil Medical Center between January 1990 and June 2001, our study group included 3 patients with Ph-positive CML with marked thrombocytosis (>600/L) and mild leukocytosis (/L) and 12 patients of the typical ET as a control group. Results : Peripheral blood basophilia (4-12%) and a few immature granulocytes (1-9%) were the characteristic features of CML with thrombocythemic onset, compared with the typical ET. There was no evidence of bone marrow eosinophilia, basophilia, or fibrosis in CML with thrombocythemic onset. Conclusions : Our study suggests that peripheral basophilia as well as the positivity of Ph chromosomes or bcr/abl gene rearrangement can be a clue to diagnosis of CML.