Immunohistochemical Expression of BCL10 and Three Markers in Extranodal Marginal Zone Lymphoma and Other Small B-Cell Lymphomas

Abstract

Abstract Extranodal marginal zone lymphoma (EMZL) is a low-grade B-cell lymphoma representing about the third most common non-Hodgkin lymphoma in the Western world. EMZL shows heterogeneous morphological features and expresses no specific immunohistochemical markers except B-cell markers. BCL10 and MALT mutations causing NF-kB pathway activation play an important role in oncogenesis of EMZL. Aberrant nuclear expression of BCL10 is reported in some EMZLs. Nuclear expression of BCL10 has not been well compared between EMZL and other small B-cell lymphomas. The aim of this study is to evaluate the expression of BCL10 and three markers in different small B-cell lymphomas. Tissue microarray blocks and selected tissue blocks, formalin fixed and paraffin embedded, were selected for immunohistochemical (IHC) studies. More than 100 cases of different small B-cell lymphomas include EMZL, small lymphocytic lymphoma (SLL), mantle cell lymphoma (MCL), follicular lymphoma (FL), lymphoplasmacytic lymphoma (LPL), and hairy cell leukemia (HCL) in the bone marrow biopsy. Commercially available antibodies from DAKO for BCL-10, IRTA-1, LEF-1, and SOX-11 were used according to the protocol. Immunoreactivity in greater than 20% of the tumor cells was considered positive. BCL-10 nuclear expression occurred mostly in EMZL but also in other small B-cell lymphomas except LPL and HCL. Cytoplasmic expression of IRTA-1 was detected in all cases of EMZL and also in SLL, MCL, and FL cases; it was negative in LPL and HCL. Nuclear expression of LEF-1 was detected mostly in SLL cases, a few cases of MZL, and none of the cases of MCL, FL, LPL, and HCL. Nuclear staining of SOX11 was found in most MCL cases; it was negative in all cases of SLL, EMZL, FL, LPL, and HCL. The IHC markers of BCL-10, IRTA-1, LEF-1, and SOX11 increase our ability to make accurate diagnosis of small B-cell lymphomas.