Site-Specific Morphologic Differences in Extranodal Marginal Zone B-Cell Lymphomas

Abstract

Abstract Context.—Lymphoepithelial lesions (LELs) are a useful diagnostic feature of extranodal marginal zone B-cell lymphoma (EMZL); however, there is scant literature comparing their frequency and morphology at various sites. Objective.—To evaluate any diagnostically useful, site-specific, morphologic patterns in EMZLs. Design.—In this retrospective review, we evaluated 136 EMZLs from different sites for LEL pattern and other pathologic differences, including CD43 coexpression and plasma cell component features. Results.—Prominent and destructive LELs were most common in salivary and thyroid gland cases, and LELs were rare to absent in breast, skin, and ocular adnexa cases. An LEL pattern with lymphocytes “stuffing” glandular lumina was seen in lung, thyroid, and salivary gland cases. Monoclonal plasma cells were most common in breast, upper aerodigestive tract, skin, and salivary gland cases. CD43 coexpression was seen in 36% of cases, most commonly in salivary gland, stomach, and upper aerodigestive tract. Conclusions.—The relative importance of LEL pattern, CD43 coexpression, and clonal plasma cell component in EMZLs is site-dependent, and the differences may aid in the diagnosis of EMZLs at different anatomic sites.