Improved Detection of Diffuse Large B-Cell Lymphoma by Flow Cytometric Immunophenotyping – Effect of Tissue Disaggregation Method
Bethany D Vallangeon, Christy Tyer, Anand Lagoo. Duke University Medical Center, Durham, NC
Background: Flow cytometric immunophenotyping is recognized as a rapid, sensitive and accurate method for diagnosis of B-cell lymphomas. We observed that flow cytometry failed to identify the clonal B-cell population in several cases of large B-cell lymphoma (DLBCL) when tissue samples were prepared by a commercially available mechanical tissue disaggregation method. To overcome this shortcoming, we tested a manual tissue disaggregation method and compared it with the mechanical method.
Design: Flow cytometry findings from 51 cases of DLBCL processed with the mechanical tissue disaggregation method, 27 cases processed using the manual method and 15 cases processed using a combination of both methods were compared. The results of the morphologic examination and immunohistochemical stains in each case were reviewed.
Results: Flow cytometry detected a clonal B-cell population in 88.9% (24/27) of cases processed by the manual tissue disaggregation method, but only in 66.7% (10/15) of cases processed by a combination of the manual and mechanical disaggregation methods, and in 62.7% (32/51) of cases processed solely by the mechanical tissue disaggregation method (p < 0.01 Fisher exact). Among the cases which were negative by flow cytometry, necrosis was noted microscopically in 66.7% (2/3) of those processed manually compared to 42.1% (8/19) of those processed mechanically. Manual processing yielded positive flow cytometry results in 81.8% (9/11) of the nodal tissue samples and 93.8% (15/16) of the extra-nodal tissue samples, whereas mechanical disaggregation was particularly inefficient in preserving large lymphoma cells from extranodal tissue: 71.4% (10/14) of the nodal tissue samples and 56.8% (21/37) of the extra-nodal tissue samples processed by the mechanical method showed clonal B-cells by flow cytometry (p < 0.006, Fisher exact).
Conclusions: The diagnostic yield of flow cytometry in diffuse large B-cell lymphoma can be significantly improved by utilizing a manual disaggregation method, particularly in extra nodal tissue samples.
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 284, Wednesday Morning