Hidden “Preleukemic Phase” of Chronic Myeloid Leukemia Presenting Without Leukocytosis in the Peripheral Blood Unrelated to Chemotherapy in a Patient Diagnosed With Diffuse Large B Cell Lymphoma

Abstract

Dear Editor, Almost all cases of CML show typical clinical features such as marked leukocytosis in the peripheral blood (PB), splenomegaly, and granulocytic hyperplasia in the PB and bone marrow (BM). CML without leukocytosis in the PB is rare but could occur if “undiagnosed” CML patients received cytoreductive therapy due to the patient’s predisposing hematologic malignancies. In contrast, the presence of the BCR-ABL1 mutation without the clinical features of CML and unrelated to cytoreductive therapy (so-called “preleukemic phase” or “smoldering” CML) is very rare [1-3]. Here, we report a rare case of hidden preleukemic phase of CML presenting without leukocytosis in the PB unrelated to prior chemotherapy in a diffuse large B cell lymphoma (DLBCL) patient. To our knowledge, this is the first case of preleukemic phase of CML in the Korean population.