Acute Myeloid Leukemia (AML) and Chronic Myeloid Leukemia (CML) are two distinct types of leukemia that affect the myeloid cells in the bone marrow. While both are forms of leukemia, they have different characteristics in terms of onset, progression, and treatment. Here are some key differences between AML and CML:
- Onset and Progression:
- AML: AML is characterized by the rapid proliferation of immature myeloid cells (blast cells) in the bone marrow. It typically presents with symptoms such as fatigue, easy bruising or bleeding, fever, and recurrent infections. AML progresses rapidly and requires prompt treatment.
- CML: CML is characterized by the excessive production of mature and immature myeloid cells, particularly granulocytes, in the bone marrow. It often presents with mild or no symptoms initially and may be incidentally discovered during routine blood tests. CML typically progresses slowly through three phases: chronic phase, accelerated phase, and blast crisis.
- Blood Cell Counts:
- AML: In AML, blood cell counts may show cytopenias (low levels of red blood cells, white blood cells, and platelets) due to the replacement of normal bone marrow cells by leukemia cells. Peripheral blood smears may show increased numbers of blast cells.
- CML: In CML, blood cell counts may show leukocytosis (elevated white blood cell count), particularly with an increase in granulocytes (neutrophils, eosinophils, and basophils). The Philadelphia chromosome (a genetic abnormality) is present in the majority of CML cases and can be detected through cytogenetic testing.
- Bone Marrow Examination:
- AML: Bone marrow examination typically reveals hypercellularity with an increased number of blast cells (typically >20% of total nucleated cells). AML is classified into different subtypes based on the morphology, immunophenotype, and genetic abnormalities of the blast cells.
- CML: Bone marrow examination in CML may show hypercellularity with an increased number of granulocytes, including mature and immature forms. The presence of the Philadelphia chromosome or its molecular counterpart (BCR-ABL fusion gene) confirms the diagnosis of CML.
- Treatment:
- AML: Treatment of AML usually involves intensive chemotherapy, sometimes followed by stem cell transplantation in eligible patients. Targeted therapies may also be used in certain cases.
- CML: Treatment of CML often involves targeted therapy with tyrosine kinase inhibitors (TKIs) such as imatinib, dasatinib, or nilotinib. TKIs are highly effective in controlling the disease and can lead to long-term remission in many patients.
In summary, while both AML and CML are forms of leukemia affecting myeloid cells, they differ in terms of onset, progression, blood cell counts, bone marrow characteristics, and treatment approaches. Diagnosis and differentiation between the two rely on clinical evaluation, laboratory tests, and bone marrow examination.