[1254] Characterization of B-Cell Lymphoma Unclassifiable with Features Intermediate between Diffuse Large B-Cell Lymphoma and Burkitt's Lymphoma: A Ten Year Retrospective Review.

Lori Edwards, Vinai Bhagirath, Elizabeth Krakow, Christine Keng, Alice Lytwyn, Cathrine Ross, Lehana Thebane, Emmy Cheng, Monalisa Sur. McMaster University, Hamilton, ON, Canada

Background: In 2008 the World Health Organization (WHO) proposed the BCLU category for high grade lymphomas clinically resembling DLBL but with more aggressive histological features and showing morphology more similar to BL. The behavior of BCLU is not well defined. Our goal was to describe the clinical and pathologic features of BCLU compared to DLBL.
Design: We searched pathology reports from 1998-2008 using the terms “Burkitt, atypical Burkitt, DLBL with BL features, DLBL with high proliferation index/Ki67” to identify potential BCLU cases. A similar number of DLBL cases, matched for year of diagnosis, were randomly selected. Two pathologists, blinded to the original diagnosis, together reviewed the cases using 2008 WHO criteria to confirm cases of BCLU and DLBL. Clinical charts were reviewed. BCLU cases with sufficient material were tested for Bcl2 and MYC genetic abnormalities.
Results: There were 34 BCLU and 97 DLBL cases. Median age was 63 years for BCLU and 67 years for DLBL. CNS involvement was present in 6 (20%) of BCLU and 4 (5%) of DLBL (p=0.01), and bulky disease in 12 (40%) of BCLU and 18 (20%) of DLBL (p=0.02). There was no significant difference in gender, International Prognostic Index, Ann Arbor stage, or marrow involvement. Median overall survival (OS) for BCLU and DLBL was 330 and 837 days, respectively, Hazard Ratio (HR) for OS was 2.5, 95%CI 1.2-5.2, adjusting for IPI and treatment. Median progression-free survival (PFS) for BCLU and DLBL was 213 and 649 days, respectively, HR 2.0, 95%CI 1.0-3.9, adjusting for IPI and treatment. Disease progression while on treatment occurred in 9 (33%) of BCLU and 8 (10%) of DLBL (p=0.03). Five BCLU patients received BL chemotherapy regimes, while 24 received CHOP-based DLBL therapy. Nine of 24 (38%) BCLU tested had abnormalities in both Bcl2 and MYC genes, called double hits (DH). Bulky disease was present in 63% of DH and 13% of non-DH; OS for DH was worse than non-DH, HR 13.8; 95%CI 2.3-83.6.
Conclusions: Compared to DLBL, patients with BCLU appeared to have more frequent CNS involvement and bulky disease, more frequent disease progression while on treatment and worse OS and PFS. BCLU with DH may have a worse prognosis, but these findings are limited by the small sample size. This is the first study to demonstrate that the clinical outcome of the new BCLU entity appears to be distinct from DLBL and further studies into more effective treatment regimes are necessary.
Category: Hematopathology

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 182, Monday Morning


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