From the Guidelines
Leukemia is diagnosed through a combination of blood tests, bone marrow examination, and other specialized tests, with the most critical step being the identification of abnormal cells in the blood or bone marrow, as stated in the study by 1. To diagnose leukemia, a complete blood count (CBC) is initially performed to identify abnormal white blood cell counts, anemia, or low platelet counts.
- If leukemia is suspected, a bone marrow aspiration and biopsy are performed to examine a sample of bone marrow under a microscope for abnormal cells.
- Flow cytometry and cytogenetic analysis are used to identify specific types of leukemia by analyzing cell markers and chromosomal abnormalities, as recommended by 1 and 1.
- Additional tests may include lumbar puncture to check for leukemia cells in cerebrospinal fluid, imaging studies like CT scans or X-rays to assess organ involvement, and molecular testing to detect genetic mutations associated with certain leukemia types. The diagnosis of chronic lymphocytic leukemia (CLL), for example, requires the presence of ≥5000 monoclonal B lymphocytes/µl in the peripheral blood for at least 3 months, as well as confirmation of clonality by flow cytometry, as stated in the study by 1.
- CLL cells are characterized by the expression of CD5, CD19, CD20, and CD23, and the levels of surface immunoglobulin, CD20, and CD79b are typically low compared to normal B cells.
- The diagnosis of other types of leukemia, such as acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML), requires different diagnostic criteria and tests, as discussed in the study by 1. The most recent and highest quality study, 1, provides the most accurate and up-to-date guidelines for the diagnosis of leukemia, and should be prioritized in clinical practice.
From the Research
Diagnosis of Leukemia
The diagnosis of leukemia can be achieved through various methods, including:
- Flow cytometry: This is the preferred method for diagnosing and immunophenotyping acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) 2, 3, 4
- Immunohistochemical staining of bone marrow biopsy specimens: This method can be used to provide immunophenotypic information when flow cytometry is unavailable 2, 4
- Morphologic, cytochemical, and immunotyping analysis: These methods can be used to classify leukemia into different subtypes 2, 3, 4
Immunophenotyping Markers
Various immunophenotyping markers can be used to diagnose and subtype leukemia, including:
- CD3, CD7, CD5 (for T lymphocytes lineage) 3
- CD19, CD22, CD20, CD10 (for B lymphocytes lineage) 3
- CD13, CD14, CD33 (for myeloid subsets) 3
- TDT, HLA-DR, CD45 (non lineage restricted) 3
- CD34, antimyeloperoxidase (anti-MPO), antihemoglobin, factor VIII-related antigen, and 3 epitopes of CD68 (HAM56, KP1, and PG-M1) 4
- Myeloperoxidase (MPO), terminal deoxynucleotidyl transferase (TdT), CD10, CD20, CD79a, CD3 2
Comparison of Diagnostic Methods
Studies have compared the results of flow cytometry and immunohistochemical staining of bone marrow biopsy specimens, and found significant concordance between the two methods 2, 4. Additionally, the expression levels of markers in peripheral blood and bone marrow samples have been compared, and found to be correlated in some cases 3.