Chronic myelogenous leukemia
Chronic myelogenous leukemia (CML)
Updated: 04/20/2021
© Jun Wang, MD, PhD
General features
- Most common chronic myeloproliferative neoplasm
- Clonal proliferation of pluripotent granular stem cells
- All ages affected, median age 50-60
Clinical presentations
- Insidious onset with anemia, fatigue, weight loss
- Extramedullary hematopoiesis causing massive hepatosplenomegaly and lymphadenopathy
Clinical course
- Chronic phase: Usually for 3-4 years, < 10% blasts in the bone marrow, readily controlled with oral medications
- Accelerated phase: 10-19% blasts in blood or marrow, >20% basophils in blood, persistent platelet count <100K or >1000K, increasing splenomegaly or white blood cell count while on therapy, marked myelofibrosis, additional cytogenetics abnormalities, lack of response to treatment
- Blast transformation (phase): > 20% or more blasts in marrow or blood, often death shortly
Key pathogenesis
- Translocation resulted abnormal activation of ABL: non-receptor tyrosine kinase in nuclei, regulating cell division, adhesion, differentiation
Key Laboratory findings
- Leukocytosis with left shift
- Basophilia
- Monocytosis, usually <3%
- Low leukocyte alkaline phosphatase (LAP) score
- Thrombocytosis
Key morphological features
- Hyper-cellular marrow due to increased granulocytic series
- Commonly normal erythroid components
- Myeloid cells in all stages
- Usually NO dysplasia
Differential diagnosis
- Acute myeloid leukemia (AML): Blasts > 20% or cytogenetic findings
- Chronic myelomonocytic leukemia: High monocytic count
- Chronic neutrophilic leukemia
- Sustained proliferation of mature neutrophils
- May be asympatomatic
- >80% combined segmented neutrophils or bands, <10% immature granulocytes and <1% myeloblasts in peripheral blood or <5% in marrow
- Normal morphology of monocytic and megakaryocytic series
- CSF3R mutation in 80% pts
- NO PDGFRA, PDGFRB, FGFR1 nor BCR-ABL
- Thrombocythemia: No or little granulocyte or erythroid proliferation
- Leukemoid reactions: Toxic granulation, a HIGH LAP score, an obvious cause for the neutrophilia
Genetic abnormalities
- t(9;22) (q34;q11), Philadelphia chromosome: BCR-ABL
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