Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ INTRODUCTION ++ The marginal zone lymphomas (MZLs) are derived from memory-type or antigen-experienced B cells that reside in regions contiguous to the outer part of the mantle zones of B-cell follicles. The World Health Organization (WHO) defines three separate MZL entities, namely, the extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (currently known as MALT lymphoma), the nodal marginal zone B-cell lymphoma (previously termed monocytoid lymphoma), and the splenic marginal zone B-cell lymphoma (with or without circulating villous lymphocytes). Gastric MALT lymphoma is one of the best examples of a microbiologic (Helicobacter pylori) cause of a human malignancy. ++ PATHOPHYSIOLOGY ++ MALT lymphomas arise from mucosa-associated lymphoid tissues in the context of chronic inflammation. In addition to H pylori, other bacteria are possibly implicated in the pathogenesis of MZLs arising in the skin (Borrelia burgdorferi), in the ocular adnexa (Chlamydophila psittaci), and in the small intestine (Campylobacter jejuni). Hepatitis C virus (HCV) appears involved in the pathogenesis of splenic MZL through antigen-driven stimulation of the lymphoma clone. There is, however, a great geographic variation in the strength of these associations, which is not satisfactorily explained. An increased risk of developing MALT lymphoma has been also reported in individuals affected by autoimmune disorders, especially Sjögren syndrome and systemic lupus erythematosus. Several recurrent chromosomal translocations have been described in extranodal MZLs. Three of them—[t(11;18)(q21;q21), t(1;14)(p22;q32), and t(14;18)(q32;q21)]—are the best characterized; they each affect the same signaling pathway, activating nuclear factor-kappa B (NF-κB), a transcription factor that plays a major role in immunity, inflammation, and apoptosis (Table 63–1). ++Table Graphic Jump LocationTABLE 63–1COMMON GENETIC LESIONS IN MUCOSA-ASSOCIATED LYMPHOID TISSUE LYMPHOMAView Table|Favorite Table|Download (.pdf) TABLE 63–1 COMMON GENETIC LESIONS IN MUCOSA-ASSOCIATED LYMPHOID TISSUE LYMPHOMA Lesion Genes Frequency Sites Translocations t(11;18)(q21;q21) t(14;18)(q32;q21) t(1;14)(p22;q32) t(3;14)(p13;q32) BIRC3-MALT1 IGHV-MALT1 IGHV-BCL10 IGHV-FOXP1 15%–40% 20% < 5% < 5% Stomach, lung Lung, skin, ocular adnexa, salivary gland Stomach, lung Unclear Gains +3; +3q +18; +18q 20%–40% 20%–40% No differences in sites No differences in sites Losses –6q23 TNFAIP3 15%–30% No differences in sites BCL-10, B-cell CLL/lymphoma 10 gene; BIRC3, baculoviral IAP repeat-containing 3 gene; FOXP1, forkhead box P1 gene; IGHV, immunoglobulin heavy-chain variable region gene; MALT1, mucosa-associated lymphoid tissue translocation gene 1; TNFAIP3, tumor necrosis factor-α–induced protein 3 gene. Source: Williams Hematology, 9th ed, Chap. 101, Table 101–1. ++ EXTRANODAL MARGINAL ZONE LYMPHOMAS ++ Clinical Features ++ The most common site of MALT lymphoma is the stomach, representing at least one-third of all cases. Extranodal MZLs may also arise at many other sites, including the salivary gland, the thyroid, the upper airways, the lung, the ocular adnexa (lacrimal gland, conjunctiva, eyelid, orbital soft tissue), the breast, the liver, the urogenital system, the skin and other soft tissues, and even the dura. As ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. What is MyAccess? Create a FREE MyAccess profile to: Use this site remotely Bookmark your favorite content Track your self-assessment progress and more!