What are the diagnostic criteria for Chronic Lymphocytic Leukemia (CLL)?

From the Guidelines

The diagnosis of Chronic Lymphocytic Leukemia (CLL) requires the presence of at least 5 x 10^9/L monoclonal B-lymphocytes in the peripheral blood, confirmed by flow cytometry, as stated in the most recent guidelines 1. The diagnostic criteria for CLL include the presence of monoclonal B-lymphocytes with a specific immunophenotype, which can be confirmed by flow cytometry using cell surface markers such as CD19, CD5, and CD23.

• The diagnosis of CLL can be made based on the presence of at least 5 x 10^9/L monoclonal B-lymphocytes in the peripheral blood, as stated in the guidelines 1.
• Flow cytometry of peripheral blood with immunophenotyping is adequate for the diagnosis of CLL, and bone marrow biopsy is generally not required, according to the guidelines 1.
• Evaluation of cyclin D1, FISH analysis for t(11;14), and flow cytometry evaluation of CD200 may be helpful in the differential diagnosis of CLL, especially to exclude other CD5+B-cell lymphoproliferative disorders, such as mantle cell lymphoma, as mentioned in the guidelines 1.
• The diagnosis of Small Lymphocytic Lymphoma (SLL) requires the presence of lymphadenopathy and/or splenomegaly with < 5 x 10^9/L B-lymphocytes in the peripheral blood, and should ideally be confirmed using lymph node biopsy, as stated in the guidelines 1. Key points to consider in the diagnosis of CLL include:
• The presence of monoclonal B-lymphocytes in the peripheral blood, confirmed by flow cytometry 1.
• The specific immunophenotype of the B-lymphocytes, including the expression of CD19, CD5, and CD23 1.
• The absence of lymphadenopathy, organomegaly, or cytopenias does not exclude the diagnosis of CLL, as stated in the guidelines 1. It is essential to note that the guidelines from 2020 1 take precedence over the older guidelines from 2011 1, as they provide the most recent and up-to-date information on the diagnostic criteria for CLL.

From the Research

Diagnostic Criteria for Chronic Lymphocytic Leukemia (CLL)

The diagnostic criteria for CLL include:

• The presence of ≥5000 clonal B-lymphocytes/μL in peripheral blood, as stated in 2, 3, 4
• The coexistence of specific surface markers, such as CD19, CD5, CD20, and CD23, demonstrated by flow cytometry, as mentioned in 2, 3, 4, 5
• The restriction of light chain immunoglobulin, as noted in 3
• The lack of expression of antigens CD22 and CD79b, as stated in 3
• A bone marrow biopsy is not mandatory for the diagnosis, as mentioned in 2
• The presence of cytopenia caused by a typical bone marrow infiltrate establishes the diagnosis of CLL, regardless of the number of circulating lymphocytes or existing lymph node involvement, as stated in 4

Immunophenotypic Characteristics

The immunophenotypic characteristics of CLL include:

• Expression of CD5, CD19, dim CD20, dim CD22, CD23, bright CD43, dim CD45, dim to negative CD79b, dim CD81, CD200, and dim monoclonal surface immunoglobulin, as described in 5
• The characteristic immunophenotype allows a definitive diagnosis and the ruling out of another leukemia or lymphoma, as mentioned in 5

Flow Cytometry

Flow cytometry is vital for diagnosis and provides important prognostic information and accurate assessment of response to therapy, as stated in 5

• Optimal specimen collection, red cell lysis, appropriate panel, cell staining, acquisition on a flow cytometer, and analysis for CLL specimens are essential for accurate diagnosis, as described in 5

Guidelines for Clinical Protocols

The National Cancer Institute (NCI)-sponsored Chronic Lymphocytic Leukemia (CLL) Working Group developed a set of standardized eligibility, response, and toxicity criteria for clinical trials, as mentioned in 6

• The guidelines include recommendations for diagnostic criteria, clinical staging, response criteria, and toxicity criteria, as stated in 6