From the Guidelines
A diagnosis of leukemia, such as chronic lymphocytic leukemia (CLL), requires a comprehensive evaluation of CBC results, including the presence of ≥5000 B lymphocytes/µl in the peripheral blood for at least 3 months, as stated in the ESMO clinical practice guidelines 1. When interpreting CBC results for leukemia, several key findings are notable:
- An elevated white blood cell count, which may include abnormal white blood cells or blasts in the peripheral blood
- Anemia, characterized by a low red blood cell count and hemoglobin, resulting from bone marrow infiltration by leukemic cells
- Thrombocytopenia, or a low platelet count, also due to bone marrow infiltration
- Neutropenia, or a low neutrophil count, which can increase the risk of infection
- Abnormal cell morphology, which can be detected through flow cytometry and other diagnostic tests These CBC abnormalities can vary depending on the type of leukemia, with acute leukemias often showing more dramatic changes than chronic forms, as noted in the guidelines for CLL diagnosis, treatment, and follow-up 1. Key characteristics of CLL cells, as identified by flow cytometry, include:
- Co-expression of the T-cell antigen CD5 and B-cell surface antigens CD19, CD20, and CD23
- Low levels of surface immunoglobulin, CD20, and CD79b compared to normal B cells
- Restricted expression of either κ or λ immunoglobulin light chains The diagnosis of CLL and other types of leukemia ultimately requires a combination of CBC results, flow cytometry, and other diagnostic tests, such as bone marrow examination and molecular testing, to confirm the presence of leukemic cells and determine the best course of treatment 1.
From the Research
Leukemia CBC Results
- A complete blood count (CBC) is usually performed to reveal leukocytosis and other abnormally elevated or depressed cell lines in patients with suspected leukemia 2, 3.
- The diagnosis of leukemia is confirmed by further examination of the bone marrow or peripheral blood 2, 3.
- Acute myeloid leukemia (AML) can be diagnosed based on peripheral blood or bone marrow blasts, and bone marrow evaluation plays a crucial role in the diagnosis, management, and follow-up of AML patients 4.
- Flow cytometry is a valuable tool in the diagnosis and classification of leukemia, allowing for the distinction between lymphoid and myeloid leukemias and the identification of specific immunophenotypic features 5, 6.
- Immunohistochemistry can also be used to subtype AML in routinely processed bone marrow biopsy specimens, with significant concordance with flow cytometric results 5.
Subtypes of Leukemia
- The four broad subtypes of leukemia are acute lymphoblastic, acute myelogenous, chronic lymphocytic, and chronic myelogenous 2, 3.
- Acute lymphoblastic leukemia occurs more often in children, whereas the other subtypes are more common in adults 2, 3.
- Each subtype has distinct clinical, morphologic, immunologic, and molecular characteristics, and accurate diagnosis and classification are crucial for predicting prognosis and guiding treatment 6.
Diagnostic Techniques
- Bone marrow biopsy or peripheral blood smear is used to confirm the diagnosis of leukemia 2, 3.
- Flow cytometry is used to immunophenotype leukemia cells and distinguish between different subtypes 5, 6.
- Immunohistochemistry can be used to subtype AML in bone marrow biopsy specimens 5.
- Multiparameter flow cytometry is an invaluable tool in the diagnosis, classification, and monitoring of patients with acute leukemia 6.