[1440] Flow Cytometric Immunophenotype of Myc-Rearranged vs. Non-Myc–Rearranged Aggressive B Cell Lymphomas

Diana Mandelker, David M Dorfman, Betty Li, Olga Pozdnyakova. Brigham and Women's Hospital, Boston, MA

Background: High grade B cell lymphomas are aggressive neoplasms warranting early and intensive treatment. Recently, several studies have shown in DLBCL that MYC translocation is an independent poor prognostic marker, and patients with a “double hit” lymphoma (DHL) involving MYC and BCL-2 or BCL-6 translocations fare even worse. While RCHOP remains the standard of care for most cases of DLBCL, other chemotherapy regimens are currently being used for high grade B cell lymphomas with a MYC translocation. While immunohistochemisty and cytogenetics can take days to weeks to yield a definitive diagnosis, flow cytometry is rapid and often the first result rendered in a hematopathology workup. Distinguishing between aggressive B cell lymphomas by immunophenotype could help guide cytogenetic workups, as well as early therapeutic interventions. Based on flow cytometric analysis, we propose an immunophenotypic pattern that is associated with MYC rearrangement in these neoplasms.
Design: We analyzed the flow cytometry immunophenotype for CD19, CD20, CD10, CD38, and CD45 for 11 Burkitt Lymphomas, 15 DHL, 7 MYC+ DLBCL, and 13 MYC- DLBCL. For those cases that were quantifiable and comparable, we determined the relative fluorescence intensity for the above markers.
Results: Relative fluorescence intensity of CD19, CD20, CD10, CD38, and CD45 in MYC rearranged versus non-myc rearranged aggressive lymphomas.

 Burkitt (n=6)Double Hit (n=7)DLBCL MYC+ (n=6)DLBCL (n=8)MYC+ vs. MYC-
CD19, median80009000950015000p=0.18
CD20, median4000500040008500p=0.02
CD10, median2500500035001500p=0.04
CD38, median4000020000300009000p=0.003
CD45, median55006000800010000p=0.01

Conclusions: A pattern of four flow cytometry markers can distinguish between myc rearranged and non-myc rearranged aggressive B cell lymphomas. MYC rearrangement appears to correlate with dimmer CD20 (p= 0.02) and CD45 (p=0.01), and brighter CD10 (p=0.04) and CD38 (p= 0.003) expression, when compared to non-MYC rearranged DLBCL. Bright CD38 expression has the strongest association with MYC rearrangement among these markers. Of note, the MYC- DLBCLs analyzed in this study were highly aggressive, with a mean Ki67 index of 80%. Therefore, it is the cytogenetic rearrangements and not grade of lymphoma that is associated with the observed flow cytometry immunophenotype. Finally, at least two prior reports have associated dim CD20 expression with DHL. In our study, CD20 was likely to have dim expression in all MYC-rearranged aggressive B cell lymphomas suggesting that this immunophenotype may correlate with MYC status and not just double hit status.
Category: Hematopathology

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 215, Wednesday Afternoon


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