Molecular and Clinicopathologic Significance of Gene Alteration Associated with MALT Lymphoma

API2-MALT1融合基因是从t(11;18)（q21;q21）染色体易位中克隆出来的，是一种粘膜相关淋巴组织（MALT）结外边缘区b细胞淋巴瘤特异性的基因异常。然而，这种嵌合基因的临床病理意义仍有待阐明。我们开发了一种非常敏感的多重RT-PCR检测API2-MALT1融合转录物，使用石蜡材料作为RNA来源，并对这种基因异常进行了大型队列研究。我们对大量肺部MALT淋巴瘤的数据表明，API2-MALT1融合可能是一种与自身免疫性疾病无关的致病基因异常。此外，这种改变可能定义了一种同质MALT淋巴瘤亚型，临床上更惰性，组织学上更“典型”。胸腺MALT淋巴瘤的研究数据进一步支持了我们关于API2-MALT1融合与自身免疫性疾病无关的观察。异常的核BCL10表达可能作为筛查肺MALT淋巴瘤中API2-MALT1融合的工具，但在皮肤MALT淋巴瘤中并非如此。本文报告1例罕见的食道及输尿管MALT淋巴瘤。

API2-MALT1 fusion gene, cloned from t(11;18)(q21;q21) chromosomal translocation, is a gene abnormality specific to extranodal marginal zone B-cell lymphoma of mucosal-associated lymphoid tissue (MALT). However, the clinicopathologic significance of this chimeric gene remains to be clarified. We have developed a very sensitive multiplex RT-PCR assay for the API2-MALT1 fusion transcript using paraffin materials as a source of RNA, and enabled a large cohort study on this gene abnormality. Our data of a large series of pulmonary MALT lymphoma suggest that the API2-MALT1 fusion may be a causative gene abnormality unrelated to autoimmune disease. In addition, this alteration may define a homogeneous MALT lymphoma subtype that is clinically more indolent and histologically more "typical". Our observation that API2-MALT1 fusion is independence of autoimmune disease is further supported by the data obtained from the study of thymic MALT lymphoma. Aberrant nuclear BCL10 expression may have a possible role as a tool to screen for this API2-MALT1 fusion in pulmonary MALT lymphoma, but this is not the case with cutaneous MALT lymphoma. Case of rare esophageal and ureteral MALT lymphomas have been reported.