IntroductionChronic Myeloid Leukemia (CML) is a clonal disorder of hematopoietic stem cells, characterized by the presence of a specific chromosomal translocation, t(9;22)(q34;q11), which generates the so-called Philadelphia chromosome (Ph), denoted as 22q–. This cytogenetic abnormality results in the fusion of the ABL1 gene on chromosome 9 with the BCR gene on chromosome 22, producing the BCR–ABL1 fusion gene. The resulting fusion protein exhibits constitutive tyrosine kinase activity, driving uncontrolled cell proliferation. While the molecular basis and downstream signaling pathways of CML are well elucidated, the initial events that trigger this translocation remain unclear. (1) Chronic Lymphocytic Leukemia (CLL) is defined by the clonal expansion and progressive accumulation of mature B lymphocytes, most of which express the CD5 antigen. These cells infiltrate the peripheral blood, bone marrow, lymphatic tissues, and spleen. The initiating leukemogenic event is thought to occur at the level of multipotent hematopoietic stem cells with self-renewal capacity, although the precise pathogenesis remains an area of active investigation. (2) Chronic Lymphocytic Leukemia (CLL) is the most prevalent form of leukemia in adults across Western countries. Its incidence is comparable between Europe and the United States, estimated at approximately 4 to 6 cases per 100,000 individuals annually. In 2014, around 15,720 new cases were projected in the U.S., alongside over 12,000 new diagnoses within Europe. The likelihood of developing CLL increases substantially with age, with over 70% of patients diagnosed at 65 years or older. (3)However, coexistence of CML and CLL in a single patient is exceedingly rare, and there are few documented cases of this in the medical literature, with only a limited number of cases reported in the medical literature. Documented presentations include both sequential diagnoses, where one malignancy follows the other, and synchronous onset, in which both entities are identified at the same time. (4) In most of the documented cases, CML has been diagnosed either following or preceding a diagnosis of CLL. Simultaneous presentation of both malignancies is exceptionally uncommon. The underlying pathogenesis of this rare co-occurrence remains poorly understood. It is still under debate whether CML and CLL in such cases originate from a common hematopoietic progenitor cell or represent independent clonal proliferations arising through separate oncogenic events. (5)In this Study, we present the case of a 79-year-old male who was concurrently diagnosed with CLL and CML, highlighting the clinical presentation, diagnostic workup, and therapeutic approach. This case underscores the importance of comprehensive evaluation in patients presenting with atypical hematological findings and contributes to the limited body of knowledge on the co-existence of CLL and CML.
