Chronic Myelogenous Leukemia CML
Chromic Myelogenous Leukemia is a myeloproliferative disorder, where there is overproduction of myeloid cells, granulocytes, that are able to differentiate to their mature forms. This type of leukemia is highly associated with a genetic alteration, specifically the Philadelphia chromosome. The Philadelphia chromosome is an abnormal chromosome made from the translocation of a piece from chromsome 9 to chromsome 22. This chromosomes genetic blueprint, begins to code for a novel fusion protein, termed the Bcr-Abl fusion protein, which is an Abl kinase, with increased and uncontrolled activity.
The average age of presentation for patients with chronic myelogenous leukemia is around 50, and compromises about 18% of all adult leukemias. The risk of this cancer is increased only be radiatioon exposure. There may be numerous additional factors that increase the risk, however, these are currently unknown.
Chronic myelogenous leukemia is a disease with three different clinical phases. The majority of patients, however, present late, and most often in the chronic phase. The chronic phase denotes an asymptomatic phase, where the symptoms of the disease are nonspecific. These include cardinal features of all hematologic malignancies, with fatigue, weight loss and night sweats, but also malaise and abdominal fullness. This phase can then progress to a more serious stage, termed the accelerated phase. During the accelerated phase, symptoms begin to worsen, and bony pain (as the malignant cells have entered the bone) appears, with bleeding, infections and itchiness from abnormal blood cell levels appears. The blastic phase describes severe infections and bleed, with a leukostasis picture, where there are so many abnormal cells in the blood, that the blood begins to become congested and hyperviscous.
Like all hematologic malignancies, you begin with the periperal blood film or also known as the peripheral blood smear. On the film, there is leukocytosis, which can often be above 100,000, with a left shift within all stages of maturation of the cells. There is also anemia, thrombocytosis, and eleveated basophils. In the chronic phase, it is rare to see blasts. On bone marrow biopsy, there is hypercellularity, with an increase in the ratio of myeloid cells versus erythroid cells. During the accelerated phase.
1) Robbins and Cotran Pathologic Basis of Disease. Seventh Edition. Kumar, V., Abbas, A.K., and Fausto, N. 2005, Elsevier Inc.