 t(11;18)(q21;q21) is associated with mucosa-associated lymphoid tissue (MALT)-type lymphoma and results in API2-MALT1 fusion.     ///    "The API2-MALT1 fusion transcript was detected in 21 of 51 (41%) cases, and was correlated with the absence of any underlying autoimmune disease, and with a normal serum lactate dehydrogenase, a ""typical"" histology without marked plasmacytic differentiation or an increased number of large cells, and aberrant nuclear BCL10 expression. "    ///    API2-MALT1 fusion defines a distinctive clinicopathologic subtype in pulmonary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue..     ///    API2-MALT1 fusion is detected most frequently in MALT lymphomas primarily involving the lung.     ///    A large-scale study with a long follow-up is necessary to establish the prognostic significance of API2-MALT1 fusion..     ///    "We therefore screened 51 cases of pulmonary MALT lymphoma for API2-MALT1 fusion, and studied its relationship with clinicopathologic factors including the immunohistochemical expression of BCL10, another MALT lymphoma-associated molecule. "    ///    "In addition, this alteration may define a homogeneous MALT lymphoma subtype that is clinically more indolent and histologically more ""typical."" Aberrant nuclear BCL10 expression may have a possible role as a tool to screen for this API2-MALT1 fusion. "    ///    These data suggest that the API2-MALT1 fusion may be a causative gene abnormality unrelated to autoimmune disease. 