From the Guidelines
The most common lab findings in leukemia subtypes vary significantly based on the specific type of leukemia, with acute myeloid leukemia (AML) typically presenting with pancytopenia, blast cells in peripheral blood, and myeloperoxidase-positive blasts on flow cytometry, as recommended by the ASCO clinical practice guideline endorsement of the College of American Pathologists and American Society of Hematology guideline 1.
Key Laboratory Findings
- In AML, patients typically present with:
- Pancytopenia
- Blast cells in peripheral blood
- Myeloperoxidase-positive blasts on flow cytometry
- In acute lymphoblastic leukemia (ALL), patients commonly show:
- Lymphoblasts in peripheral blood
- Thrombocytopenia
- Anemia
- TdT-positive cells on immunophenotyping
- In chronic myeloid leukemia (CML), patients are characterized by:
- Leukocytosis with a left shift
- Basophilia
- Low leukocyte alkaline phosphatase
- Presence of the Philadelphia chromosome (BCR-ABL fusion) on genetic testing
- In chronic lymphocytic leukemia (CLL), patients typically present with:
- Lymphocytosis (>5,000/μL)
- Smudge cells on blood smear
- CD5+/CD23+ B-cells on flow cytometry
- In hairy cell leukemia, patients show:
- Pancytopenia
- Hairy cells on peripheral smear
- Positive TRAP staining
Diagnostic Workup
The diagnostic workup for leukemia subtypes includes:
- Complete blood counts with differential
- Peripheral blood smears
- Bone marrow aspiration and biopsy
- Flow cytometry
- Cytogenetics
- Molecular studies As recommended by the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of acute myeloblastic leukaemias in adult patients 1, and the ASCO clinical practice guideline endorsement of the College of American Pathologists and American Society of Hematology guideline 1.
From the Research
Lab Findings in Leukemia Subtypes
- Chronic Myeloid Leukemia (CML) is characterized by the presence of the Philadelphia chromosome, defined by the BCR::ABL1 oncogene 2
- Approximately 90% of people with CML present with an indolent chronic phase of CML, defined as blasts of less than 10% in the blood or bone marrow 2
- The most advanced stage is CML blastic phase (CML-BP), characterized by the World Health Organization as 20% or more blasts/immature cells and by the MD Anderson Cancer Center and European LeukemiaNet as 30% or more 2
- Acute Lymphoblastic Leukemia (ALL) is characterized by chromosomal abnormalities and genetic alterations involved in differentiation and proliferation of lymphoid precursor cells 3
- Acute Myeloid Leukemia (AML) can be a complication of CML progression, with a rare and challenging transformation into mixed lineage leukemia 4
Diagnostic Challenges
- Distinguishing CML-LBC from de novo Ph+ B-ALL is crucial, as patients with CML-LBC have inferior outcomes 5
- The diagnosis of CML-LBC can be supported by features such as a large discrepancy between the blast count and Ph+ clone, Ph+ clone persistent when B-ALL in remission, and BCR/ABL1 fusion detected in segmented cells 5
- Acute transformation of CML, particularly into mixed lineage leukemia, is a rare and challenging complication 4
Laboratory Tests
- Bone marrow analysis, flow cytometry, and cytogenetics are essential for diagnosing and monitoring leukemia subtypes 2, 4
- BCR-ABL1 fusion detection is critical for diagnosing CML and distinguishing it from other leukemia subtypes 2, 5
- Genetic profiling, including genome-wide gene expression, DNA copy number, and single nucleotide polymorphism (SNP) genotype, may shed some light on the role of genetics in leukemia disparities 6