[1379] Immunohistochemical and Genetic Evaluation of MYC Translocation Positive Aggressive B Cell Lymphomas

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

Background: We evaluated a series of 449 aggressive B cell lymphomas. In this group, we found 13% harbored evidence of MYC translocations. We divided these cases into three groups: Burkitt lymphoma (BL), MYC-translocation positive diffuse large B cell lymphoma (MYC+DLBCL) and double-hit lymphoma (DHL). We compared these groups to each other as well as a large group of MYC translocation negative nodal and extranodal aggressive B cell lymphomas.
Design: 449 cases were evaluated and classified as aggressive B cell lymphomas based on clinical, histologic, immunophenotypic and genetic features. The immunohistochemical stains included CD20, CD3, CD5, CD10, cyclin D1, bcl6, bcl2, EBER, Ki67, and CD30. The panel of FISH studies included MYC, IGH/BCL2 and BCL6. 57 cases with MYC translocations were identified.
Results: We identified 23 cases of BL, 15 cases of MYC+DLBCL and 19 cases of DHL. BL had a significantly lower average age (56.8 yrs.) compared to the other types (MYC+DLBCL 83.7 yrs.; DHL 82.6 years). In all types, extranodal disease was more common than nodal disease. Most cases showed expression of CD10 and BCL6. BCL2 was positive in 6/22 BL (27%), and most cases of DHL and MYC+DLBCL. Unusual immunohistochemical findings included no expression of GCET1 in DHL, no expression of LMO2 in BL, and a complete lack of EBER staining in DHL, compared to rare cases EBER positive cases of MYC+DLBCL (1/11) and BL (2/12). In DHL, 18/19 had IGH/BCL2 translocations, with 1/19 with BCL6 translocation only, and 3/19 with concurrent MYC, IGH/BCL2 and BCL6 translocations ('triple hit').
Conclusions: MYC positive aggressive B cell lymphomas have been of considerable interest recently. They are typically associated with a poor or even dismal prognosis compared to “usual” types of DLBCL. The distinction of DHL from MYC+DLBCL and BL may be of considerable clinical importance due to prognostic and therapeutic differences in these cases. Our study illustrates some key diagnostic differences in MYC translocation positive aggressive B cell lymphomas and compares these findings to those of a large group of MYC translocation negative aggressive B cell lymphomas.
Category: Hematopathology

Monday, March 4, 2013 1:00 PM

Poster Session II # 202, Monday Afternoon

 

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