[1170] Comparison of AIDS-Related Diffuse Large B-Cell Lymphomas (AR-DLBCLs) and Immunocompetent (IC) DLBCLs Suggest Biologic Differences

A Chadburn, S Silver, L Pasqualucci, R Dalla-Favera, K Merati, M McGrath, L Ayers, JM Orenstein, DM Knowles, E Cesarman. Pathology & Laboratory Medicine, Weill Cornell Medical College; George Washington University, University of California-San Francisco, Ohio State University; Pathology & Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University; Acupath Laboratories, Plainview, NY

Background: DLBCL accounts for 30-40% of non-Hodgkin lymphoma (NHL) in western countries and about 40% of AIDS-related NHL. Although previous studies have compared AR-DLBCLs with those in IC patients, no large study comparing histogenic origin, Epstein-Barr virus (EBV) positivity and prognostic marker expression in AR-DLBCLs with IC-DLBCLs has been done.
Design: Tissue microarrays of 151 IC-DLBCLs and 115 AR-DLBCLs were studied for expression of CD10, BCL6, MUM1, BLIMP1, BCL2, p53 and EBER (EBV) using standard protocols. Cases were classified as germinal center (GC), non-GC and not GC/non-GC (null) based on the schema of Hans, et al. SPSS software was used for statistical analysis.
Results: 71/115 (62%) AR-DLBCLs were of GC, 29 (25%) of non-GC and 15 (13%) of null origin; the IC-DLBCLs were evenly divided into GC and non-GC cases (each 65; 43%; p<0.01). A larger proportion of AR than IC-DLBCL was CD10 positive (57% vs 33%; p<0.001) while BCL6 (44% vs 53%) and MUM1 (48% vs 59%) were seen in less AR cases. The number of BCL2 positive AR-DLBCLs was lower (64; 58%) than IC cases (125; 85%; p<0.001). The largest difference was in the GCs: only 47% of AR-GCs were BCL2 positive compared to 76% of IC-GCs (p<0.005). BLIMP1 was positive in <20% of AR and IC-DLBCLs; however 48% AR compared to 21% IC non-GCs were positive (p<0.05). There was no difference in p53 expression between AR and IC cases or histogenic types. 45 (39%) AR-DLBCLs and only 3 (2%) IC-DLBCLs were EBV positive (p<0.001). More non-GC AR cases were EBV positive (69%) than GC (27%) or null (40%) cases (p<0.001). Only 6% of the EBV negative ARs expressed BLIMP1 compared to 37% of the EBV positive cases (p<0.001).
Conclusions: AR-DLBCLs are more likely of GC origin, EBV positive and BCL2 negative than IC-DLBCLs. Correlation of EBV with non-GC cases and BLIMP1 expression suggest that EBV may play a role in the development of these cases although the high frequency of the GC phenotype in AR-DLBCL is surprising. These data provide new insights into differences between AR- and IC-DLBCLs.
Category: Hematopathology

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 179, Wednesday Morning