[1178] Distinct Cytogenetic Profiles of Diffuse Large B-Cell Lymphoma in Chinese and Western Population

Y Chen, BJ Dave, X Zhu, WC Chan, R Irons, K Fu. University of Nebraska Medical Center, Omaha, NE; Shanghai Cancer Hospital, Shanghai, China; Fudan University, Shanghai, China

Background: Diffuse large B-cell lymphoma (DLBCL) derived from germinal center B cells (GCB) have a better prognosis. Studies from Western countries have shown that cytogenetically GCB-DLBCL frequently exhibits the t(14;18) and gain of 12q, whereas non-GCB-DLBCL commonly shows gain of 3q, 18q and loss of 6q. However, GCB-DLBCL and the t(14;18) are significantly less frequent in DLBCL from Chinese patients. We studied cytogenetic profiles in Chinese patients with DLBCL to determine possible distinct alterations and whether there are any differences between the Chinese and western cases.
Design: Conventional cytogenetic analysis was performed on 134 Chinese patients with de novo DLBCL. Immunohistochemical analysis of CD10, BCL6, and MUM1 expression was used to categorize the GCB or non-GCB DLBCL (Hans, et al, 2004, Blood 103:275-282). Interphase fluorescence in situ hybridization (FISH) was used to determine the incidence of the t(14;18).
Results: Thirty-two of the 134 (24%) cases showed near-triploid or near-tetraploid with high chromosome number (CN) ranging from 58 to 101. The remaining 102 (76%) cases were near-diploid. Only 4 of 134 (3%) cases had the t(14;18). The most frequent genetic imbalances included whole chromosome gains of 18 (17%), 3 (14%), 5 (14%), X (11%), 7 (10%), and partial gains of 1q (16%), 7p (10%), 7q (10%). Whole chromosome losses of Y (21%), 15 (11%) and partial losses of 6q (20%), 17p (15%), and 1p (13%) were also frequently noted. We divided the 134 cases into 3 groups: GCB-DLBCL with near-diploidy (n=24), non-GCB DLBCL with near-diploidy (n=78) and DLBCL with high CN (n=32). Gain of 11q was more commonly seen in near-diploid GCB DLBCL. Gain of 7p and loss of 17p were more frequently seen in near diploid non-GCB DLBCL. Multiple ploidy-related gains and losses were noted in high CN-DLBCL, including frequent gains of 5 (34%), 20 (27%), 6p (21%), and losses of 17p (40%), 1p (35%), and 6q (35%).
Conclusions: Our studies revealed distinct cytogenetic profiles of DLBCL in Chinese compared to the reported Western patients, specifically gain of 11q in GCB-DLBCL and loss of 17p in non-GCB DLBCL cases. A very low frequency of the t(14;18) is observed in GCB-DLBCL among Chinese patients.
Category: Hematopathology

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 180, Wednesday Morning