Mature B-Cell Lymphomas with Blastoid Morphology: Clinicopathologic and Genetic Features of 33 Cases.
Rashmi Kanagal Shamannna, L Jeffrey Medeiros, Sa A Wang, Roberto N Miranda. UT MD Anderson Cancer Center, Houston
Background: Mature B-cell lymphomas occasionally exhibit blastic morphologic features that do not readily fit within the well-defined categories of mature B-cell lymphoma of the WHO classification. The goal of this study is to review the clinicopathologic, immunophenotypic, and cytogenetic findings in these cases to improve our understanding of these lymphomas.
Design: We searched our files for cases of mature B-cell lymphoma in which “blastic” or “blastoid” morphology was sufficiently distinctive to be specifically commented in pathology report. H&E and immunohistochemical slides were reviewed. We selected only cases in which >90% of tumor cells had blastic features. B-lymphoblastic lymphoma/leukemia, blastoid mantle cell lymphoma (MCL) and typical Burkitt lymphoma were excluded as they are well recognized in the current WHO system. Clinical and molecular/cytogenetic data were collected from medical records.
Results: We identified 33 cases of mature B-cell lymphoma with blastoid morphologic features. There were 18 men and 15 women with median age of 59.5 years (36-74). 21 cases were nodal, 12 cases were extranodal lymphomas at various sites. 18 patients had bone marrow (BM) involvement including 2 patients with leukemic presentation. Lymphomas were classified using WHO system as follows: 13 diffuse large B-cell lymphoma (DLBCL), a subset of which had “small centroblasts”, 11 B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma (BCLU), 5 DLBCL transformed from follicular lymphoma (FL) and 4 FL. Immunophenotypic studies showed B-cell phenotype (CD20/ Pax-5) in all cases with expression of CD10 in 20/26, Bcl-6 in 18/19, and Bcl-2 in 18/21. Median proliferation index (Ki-67) was 90%. All cases tested were negative for cyclin D1 (n=18), TdT (n=16) and CD34 (n=14). Fluorescence in situ hybridization for t(14;18)/IgH-Bcl-2 was positive in 9/14 cases and MYC was rearranged in 6/11 cases. Four cases were so-called “double hit” lymphomas. Survival data was available for 30 patients. Median overall survival was 4 months (0.1-60) with median follow-up of 11.1 months (0.1-89). 17 patients died of disease, 13 are alive at last follow-up, 3 are lost to follow-up.
Conclusions: After excluding blastoid MCL, most mature B-cell lymphomas with blastoid morphology are germinal center B-cell lymphomas with a poor prognosis. Histologic classification can be problematic as cytologic features do not readily fit into well defined WHO categories. Most of these tumors were classified as DLBCL or BCLU and a high percentage of cases tested were “double hit” lymphomas.
Wednesday, March 2, 2011 1:00 PM
Poster Session VI # 214, Wednesday Afternoon