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Marginal-Zone B-Cell Lymphoma of Extranodal Mucosa-Associated Lymphoid Tissue Type: Molecular Genetics Provides New Insights into Pathogenesis: On: The product of the t(11;18), an API2-MLT fusion, marks nearly half of gastric MALT type lymphomas without large cell proliferation. Baens M, Maes B, Steyls A, Geboes K, et al. Am J Pathol 2000; 156:1433–9On: Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas. Remstein ED, James D, Kurtin PJ. Am J Pathol 2000; 156:1183–8

Vega, Francisco; Medeiros, L. Jeffrey

Advances in Anatomic Pathology: November 2001 - Volume 8 - Issue 6 - p 313-326
Update Articles/Commentaries

Marginal zone B-cell lymphoma of extranodal mucosa-associated lymphoid tissue (MALT) type is recognized as a distinct clinicopathologic entity in the revised European-American lymphoma (REAL) and recently published World Health Organization (WHO) classifications. These neoplasms are thought to arise from the extranodal equivalent of the lymph node marginal zone. Two recurrent chromosomal translocations, to date, have been implicated in the pathogenesis of these neoplasms. The t(11;18)(q21;q21), which is far more common, disrupts the api 2 gene on chromosome 11q21 and the malt 1 (mlt) gene on chromosome 18q21, resulting in the synthesis of a novel fusion gene and protein, API2-MALT1. The t(1;14)(p22;q32), which is uncommon, juxtaposes the bcl-10 gene on chromosome 1p22 adjacent to the immunoglobulin heavy chain (IgH) gene on chromosome 14, wherein BCL10 is overexpressed via the influence of the IgH enhancer. BCL-10 may then form a complex with MALT1 in the cell. Both translocations result in increased inhibition of apoptosis, conferring a survival advantage. Recent work suggests that API2-MALT1 and BCL-10-MALT1 may activate NF-k B and a common downstream signaling pathway.

At the Division of Pathology and Laboratory Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.

Dr. Vega is a postdoctoral fellow at the University of Texas M. D. Anderson Cancer Center. He is supported by a grant from “Fundacion Pedro Barrie de la Maza,” Galicia, Spain.

Address correspondence to Dr. L. Jeffrey Medeiros, University of Texas M. D. Anderson Cancer Center, Department of Hematopathology, Box 72, 1515 Holcombe Boulevard, Houston, TX 77030. E-mail:

© 2001 Lippincott Williams & Wilkins, Inc.