Comparison of Myocyte Enhancer Factor 2B Versus Other Germinal Center-associated Antigens in the Differential Diagnosis of B-Cell Non-Hodgkin Lymphomas

Myocyte enhancer binding factor 2B (MEF2B) is a transcriptional activator of the BCL6 proto-oncogene in normal germinal center (GC) B-cells. Limited data exists concerning its expression in B-cell lymphomas, and comparison with other GC-associated antigens is lacking. Its role in the differential diagnosis of B-cell lymphomas, particularly in the distinction of follicular lymphoma (FL) versus marginal zone lymphoma (MZL), remains to be determined. We evaluated MEF2B expression, in comparison with additional GC markers, LIM domain-only transcription factor 2 (LMO2), and human GC-associated lymphoma (HGAL), in a variety of B-cell lymphomas, with particular emphasis on their utility in differentiating FL from MZL. MEF2B was positive in all FL and Burkitt lymphomas, 8/9 mantle cell lymphomas, 2/24 splenic MZL, 1/10 chronic lymphocytic leukemia/small lymphocytic lymphomas, and 38/44 diffuse large B-cell lymphoma (DLBCL), but was negative in all extranodal MZL of mucosa-associated lymphoid tissue, nodal MZL, and B-lymphoblastic lymphomas. Focusing on low-grade FL versus MZL, MEF2B was 100% sensitive and 95% specific for FL, which was similar to BCL6, but superior to LMO2 (sensitivity 87%, specificity 86%) and HGAL (sensitivity 97%, specificity 86%). Importantly, MEF2B was positive in 4/4 FL with plasmacytoid differentiation, which were CD10−, only weakly BCL6+, and included 1 case that lacked both LMO2 and HGAL expression. MEF2B was positive in 22/25 (88%) GC-type DLBCL, but was ...
Source: The American Journal of Surgical Pathology - Category: Pathology Tags: Original Articles Source Type: research