[1397] Bright CD38 and Dim CD20 by Flow Cytometry May Predict for Double Hit Lymphomas in MYC Rearranged High-Grade B-Cell Lymphomas.

Jason S Willis, Adam C Seegmiller, Naseem Uddin, Nitin J Karandikar, Weina Chen. UT Southwestern Medical Center, Dallas, TX

Background: We have previously described bright CD38 expression in CD10(+) high-grade B-cell lymphomas (HGBCL) as a predictor of MYC rearrangements (Maleki, et. al., Leuk Lymphoma. 2009;50:105). Among these lymphomas, those with MYC rearrangements and t(14;18), i.e. double hit lymphomas (DHL), carry a worse prognosis than Burkitt lymphoma (BL). In this study, we sought to identify immunophenotypic features that predict for DHL among MYC rearranged HGBCL.
Design: Searching our institutional clinical flow cytometry and cytogenetic laboratory databases yielded DHL (n=18), BL (n=22), and diffuse large B-cell lymphoma with MYC R (DLBC+M) (n=5). All cases had karyotypic results. We compared the immunophenotypic features with a focus on CD38 mean fluorescence intensity (MFI) and CD20 MFI, and additional cytogenetic abnormalities among the 3 groups.
Results: The mean CD38 MFI (1248, range 55-3143) of DHL was not different from that of BL (1611, range 620-3894) or DLBCL+M (927, range 13-2051), but was higher than that of DLBCL without MYC R (mean of 821 from our previous study). The mean CD20 MFI was 480 (range 9-1812) in DHL, 603 (range 119-1912) in BL, and 149 (range 14-410) in DLBCL+M. Compared to BL, there was a tendency to have dimmer CD20 expression in DHL (p=0.0729 by Mann-Whitney test, median 393.6 versus 534.2). The expression of CD10, CD19, CD23, and FMC-7 were similar among the 3 groups. In DHL cases, MYC R was present as follows: t(8;14) [10 cases]; t(8;22) [6 cases] and t(2;8) [2 cases]. Variant MYC/immunoglobulin (IG) light chain rearrangements was more common in DHL (40%) than in BL (4.5%). In addition, the mean of additional cytogenetic abnormalities in DHL (5.7) was higher than that of BL(1.9), but lower than DLBCL+M (15.6).
Conclusions: This study confirmed our previous observation of bright CD38 expression in MYC rearranged HGBCL. A feature of DHL that is distinct from BL is dimmer CD20 expression. Therefore, the combination of dim CD20 expression and bright CD38 expression by flow cytometry should prompt for genetic studies for rearrangements of both MYC and IG. Compared to BL, DHL is characterized, at a genetic level, by a complex karyotype and frequent variant MYC rearrangements, which suggests that MYC disruption may be a secondary event involved in disease progression.
Category: Hematopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 218, Wednesday Afternoon

 

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