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Query: UMLS:C0855152 (Primary mediastinal large B-cell lymphoma)
 46 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary mediastinal large B-cell lymphomas (LBCLs) constitute a unique subtype of diffuse LBCLs, with distinct clinical, immunophenotypic, and morphologic features. These lymphomas are thought to originate from the thymus, and it has been hypothesized that they derive from a population of B lymphocytes normally present in the thymic medulla. Most diffuse LBCLs harbor somatic mutations in their immunoglobulin genes, suggesting that they have been exposed to the germinal center. To investigate the possible relationship of mediastinal LBCLs to germinal center B cells, we analyzed the expression of bcl-6 and CD10 in 19 mediastinal LBCLs, using an immunoperoxidase technique on formalin-fixed tissue. We found that 19 of 19 (100%) mediastinal LBCLs were bcl-6+ and 6 of 19 (32%) mediastinal LBCLs were CD10+. Because mediastinal LBCLs usually lack BCL-6 gene rearrangement or mutations, expression of bcl-6 and CD10 in these tumors tends to support a germinal center derivation.
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PMID:Expression of bcl-6 and CD10 in primary mediastinal large B-cell lymphoma: evidence for derivation from germinal center B cells? 1217 99

Primary mediastinal large B-cell lymphoma (PMLBCL) is a unique type of B-cell lymphoma probably arising from a putative thymic medulla B-cell. It constitutes 6-10% of all diffuse large B-cell lymphomas (DLBCL), occurring more often in young females. PMLBCL is characterized by a diffuse proliferation of medium to large B-cells associated with sclerosis and a degree of compartmentalisation. Its main molecular characteristics include: gains in 9p segments, p53 mutations, BCL-2 and MAL gene over-expression, somatic mutations of IgVH genes, BCL-6, PIM-1, PAX-5, RhoH/TTF, and c-MYC, and constitutional NF-kappaB activation. The gene expression signature of PMLBCL seems to be much closer to classic Hodgkin lymphoma than to DLBCL. PMLBCL is characterized by a locally invasive anterior mediastinal mass, often producing cough, chest pain, dyspnea, and superior vena cava syndrome. Most PMLBCL patients have stage I-II, bulky disease, with pleural or pericardial effusions in a third of cases. Systemic symptoms, mainly fever or weight loss, are present in <20% of cases; increased LDH levels are observed in 70-80% of cases. Treatment with CHOP regimen followed by radiation therapy was associated with a 5-year survival of 65%. Apparently better results have been reported with third-generation weekly alternating regimens followed by radiation therapy. Any recurrence is almost always seen in the first 2 years of follow-up, and distant relapses tend to involve extranodal organs. Features associated with poor prognosis are poor performance status, pericardial effusion, bulky disease, high serum LDH at diagnosis, and a compromised dose-intensity of anthracycline and cyclophosphamide.
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PMID:Primary mediastinal large B-cell lymphoma. 1877 28

The physiologic expression of the product of the proto-oncogene TCL1 (T-cell leukemia 1) is primarily restricted to early embryonic cells. In nonneoplastic B cells, the expression of TCL1 is determined by the differentiation step with silencing at the germinal center stage. TCL1 protein is overexpressed in a wide variety of human diseases. It has been shown that TCL1 is a powerful B-cell oncogene, which has been implicated in the pathogenesis of various types of mature B-cell lymphomas. There is no comparative information in the literature addressing the expression of TCL1 in pediatric and adult nodal diffuse large B-cell lymphoma or primary mediastinal large B-cell lymphoma. We studied 55 cases of adult and pediatric diffuse large B-cell lymphoma and primary mediastinal large B-cell lymphoma to analyze the phenotypic profile of these lymphomas, including TCL1 expression, and its relationship with clinical outcome in different age groups. The cases were analyzed by immunohistochemistry for the expression of TCL1, CD10, BCL-2, BCL-6, and MUM1. We also evaluated c-MYC translocation by fluorescence in situ hybridization. TCL1 was observed in 11 cases, 5 pediatric and 6 adult cases, all but one diffuse large B-cell lymphoma. Pediatric cases showed a significant association between TCL1 expression, high proliferative index, and presence of c-MYC translocation. TCL1 positivity was predominantly found in germinal center phenotype diffuse large B-cell lymphoma. Overall survival was worse in adult TCL1-positive cases than pediatric ones. Primary mediastinal large B-cell lymphomas infrequently expressed TCL1 in both age groups.
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PMID:T-cell leukemia 1 expression in nodal Epstein-Barr virus-negative diffuse large B-cell lymphoma and primary mediastinal B-cell lymphoma. 2038 9