[1560] Immunohistochemical and Genetic Evaluation of EBV-Positive Aggressive B Cell Lymphomas

Dennis P O'Malley, Kate E Grimm, Renuka Agrawal, Lawrence M Weiss. Clarient Inc./GE Healthcare, Aliso Viejo, CA

Background: Diffuse large B cell lymphoma and related entities are the commonest type of non-Hodgkin lymphomas. There are several distinct clinicopathologic groups. Among these are plasmablastic lymphoma (PBL), lymphomatoid granulomatosis (LyG) and 'EBV positive large B cell lymphoma of the elderly' (EBV-LBCL-E). Each of these subgroups is rare and immunohistochemical and genetic characterization has been based on only small series. We evaluated a series of 380 large B cell lymphomas for EBV expression and compared these cases.
Design: 380 cases were evaluated for EBV expression by EBER staining. In addition, an extensive panel of immunohistochemical stains (CD20, CD3, CD5, CD10, cyclin D1, bcl6, bcl2, EBER, Ki67, CD30) and a panel of FISH studies (including MYC, IGH/bcl2 and bcl6) were performed on these cases.
Results: 23 cases of EBV-LBCL (6%), 4 cases of PBL (1%) and 4 cases of LyG (1%) were identified. Demographic findings for EBV-LBCL included 21% of cases identified in patients below the age of 50 years. IHC findings in EBV-LBCL included a low percentage of CD10 expression (11%), with high levels of MUM1 (90%), BCL2 (87%) and CD30 (100%). The majority of cases were of non-germinal center (non-GC) type by Hans classifier, with all cases non-GC-type by tally classifier. Nineteen of 23 cases had FISH studies with 26% having BCL6 translocations.
Conclusions: Our study shows the frequency, immunophenotypic and genetic findings in EBV positive LBCL to be comparable to other literature reports. We found a high frequency of non-GC type lymphomas, with a relatively high frequency of BCL6 translocations. We also found that EBV-LBCL-E may be a misnomer, as these cases appear in substantial numbers in patients below 50 years of age.
Category: Infections

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 249, Wednesday Morning


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