From the Guidelines
To rule out B cell lymphoproliferative disorders, peripheral blood studies should include flow cytometry with immunophenotyping using cell surface markers, as it is adequate for the diagnosis of chronic lymphocytic leukemia (CLL) and can help exclude other CD5+B-cell lymphoproliferative disorders, such as mantle cell lymphoma, as stated in the NCCN clinical practice guidelines in oncology 1. The diagnosis of CLL requires the presence of at least 5 x 10^9/L monoclonal B-lymphocytes in the peripheral blood, and the clonality of B cells should be confirmed by flow cytometry 1. Some key points to consider when ordering peripheral blood studies for B cell lymphoproliferative disorders include:
- Flow cytometry evaluation of CD200, and immunohistochemistry for LEF1 may be helpful in the differential diagnosis of CLL, especially to exclude other CD5+B-cell lymphoproliferative disorders, specifically mantle cell lymphoma 1.
- FISH for the detection of del(11q), del(13q), trisomy 12, del(17p), CpG-stimulated metaphase karyotype, TP53 sequencing, and molecular genetic analysis for IGHV mutation status can provide useful prognostic information and may guide selection of therapy 1.
- Evaluation of cyclin D1 (flow cytometry or immunohistochemistry) or FISH analysis for t(11;14) can also be helpful in the differential diagnosis of CLL 1. These tests should be ordered as a comprehensive panel when clinical suspicion exists, as B cell disorders often present with subtle findings like unexplained lymphocytosis, anemia, recurrent infections, or constitutional symptoms 1.
From the Research
Peripheral Blood Studies for B Cell Lymphoproliferative Disorders
To rule out B cell lymphoproliferative disorders, several peripheral blood studies can be employed, including:
- Flow cytometry: This technique plays a major role in the diagnosis of mature B-cell lymphoproliferative disorders, allowing for the rapid identification of specific immunophenotypic features 2.
- Immunophenotyping: This can be performed using either flow cytometry or immunohistochemistry, and is an important step in differentiating between benign and malignant lymphoproliferative disorders 3.
- Quantitative flow cytometry: This technique can be used to better characterize B-cell chronic lymphoproliferative disorders, by calculating the number of antigen molecules per cell 4.
- Multiparameter flow cytometry: This is necessary for the detection, characterization, and diagnostics of composite mature B-cell lymphoproliferative neoplasms, which are rare entities characterized by the simultaneous presence of two or more distinctive B-cell derived monoclonal malignancies 5.
Key Markers and Techniques
Some key markers and techniques used in these studies include:
- CD19: A mandatory gating step in the diagnosis of B-cell lymphoproliferative disorders 2.
- Surface immunoglobulin light chain restriction: Used to suspect clonal proliferation 2.
- CD5: Used to segregate chronic lymphocytic leukemia and mantle cell lymphoma 2.
- CD20, CD22, CD23: Informative cell surface antigens used in the detection of composite lymphomas 5.
- Light chain restriction analysis: Used to confirm the monoclonal nature of neoplastic clones 5.
Interpretation of Results
The results of these studies should be interpreted in an integrated manner, taking into account the patient's clinical and other biological features, and completed by further chromosomal and/or molecular investigations 2, 6.