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Published on: June 19, 2015
Diminished expression of CD19 in B-cell lymphomas
Wei Yang1, Neeta Agrawal, Jigar Patel
1University Hospitals of Cleveland and Case Western Reserve University, Cleveland, Ohio, USA.
Insights
Diminished CD19 expression is common in B-cell lymphomas, especially follicular lymphoma. This finding aids in identifying lymphoma cells in complex samples like bone marrow.
Area of Science:
- Hematology
- Immunophenotyping
- Oncology
Background:
- CD19 is a key B-cell marker, but its expression levels in various B-cell lymphomas are not fully understood.
- Low-level CD19 expression can complicate lymphoma diagnosis.
Purpose of the Study:
- To investigate the frequency and patterns of decreased CD19 expression across different B-cell lymphoma subtypes.
- To assess the diagnostic utility of CD19 dim expression in B-cell malignancies.
Main Methods:
- Retrospective review of 349 B-cell lymphoma cases using flow cytometry.
- Analysis of CD19 expression levels compared to normal B lymphocytes.
- Correlation of flow cytometry findings with morphologic diagnoses.
Main Results:
- 36% of cases exhibited decreased CD19 expression.
- Follicular lymphoma showed the highest frequency (79%) of CD19 dim expression.
- CD19 dim expression was observed in small lymphocytic lymphoma/chronic lymphocytic leukemia, mantle cell lymphoma, diffuse large B-cell lymphoma, and marginal zone lymphoma, but not in Burkitt lymphoma or hairy cell leukemia.
Conclusions:
- Diminished CD19 expression is a frequent feature in B-cell lymphomas, particularly follicular lymphoma.
- Monitoring CD19 expression levels can be valuable for diagnosing B-cell lymphomas, especially in challenging cases like bone marrow aspirates.
Background:
CD19 is expressed on most B-cell lymphomas; however, the frequency and types of B-cell lymphomas with low-level expression of CD19 are not well characterized.
Methods:
We reviewed flow cytometric histograms specifically for decreased CD19 expression on 349 cases analyzed by the Flow Cytometry Laboratory at University Hospitals of Cleveland (Cleveland, Ohio). Results of flow cytometry were correlated with the morphologic diagnosis.
Results:
Of the cases reviewed, 125 (36%) showed a visible decrease in CD19 expression compared with normal B lymphocytes. Decreased CD19 expression was noted in 79% of follicular lymphomas (27 of 34), 36% of small lymphocytic lymphomas/chronic lymphocytic leukemias (82 of 228), 31% of mantle cell lymphomas (4 of 13), 24% of diffuse large B-cell lymphomas (8 of 33), and 13% of marginal zone B-cell lymphomas/lymphoplasmacytoid lymphomas (4 of 30) and was not observed in any Burkitt lymphoma (0 of 5) or hairy cell leukemia (0 of 6). Decreased CD19 expression was significantly more frequent in follicular lymphomas than in other lymphoma subtypes (P < 0.001). No significant difference was observed in the frequency of decreased CD19 expression based on histologic grade of follicular lymphoma.
Conclusions:
Diminished expression of CD19 expression occurs frequently in B-cell lymphomas, in particular follicular lymphoma, and may be helpful in identifying B-cell lymphoma cells in complex cell mixtures such as bone marrow specimens.
