In a search for bcl-2 protein expression, we have found a significant difference between nodal (39/48) and MALT high-grade B-cell lymphoma (1/15) (P less than 0.01).
While bcl-1 rearrangement was not present in these gastrointestinal lymphomas, one case of diffuse low-grade lymphoma of mucosa-associated lymphoid tissue and three cases of centroblastic lymphoma (diffuse large cell) could be shown to have detectable bcl-2 rearrangement.
No rearrangement of bcl-1, bcl-2 or c-myc was found in any case of lymphoma of mucosa associated lymphoid tissue (MALT), providing further evidence that, in spite of having a similar morphology to some other groups of low grade B-cell lymphoma, lymphomas of MALT comprise a distinct entity.
Based on the CDR3 sequence amplified from each MALT lymphoma, individual tumor-specific primers were synthesized and used directly in the polymerase chain reaction (PCR) to analyze the sequences of their Ig heavy-chain variable region.
Based on the CDR3 sequence amplified from each MALT lymphoma, individual tumor-specific primers were synthesized and used directly in the polymerase chain reaction (PCR) to analyze the sequences of their Ig heavy-chain variable region.
Based on the CDR3 sequence amplified from each MALT lymphoma, individual tumor-specific primers were synthesized and used directly in the polymerase chain reaction (PCR) to analyze the sequences of their Ig heavy-chain variable region.
In view of recent data indicating that most high grade nodal lymphomas express bcl-2, these findings suggest that MALT lymphomas may regulate bcl-2 gene expression differently to nodal lymphomas.
In two DCC cases allele imbalance was seen in the transition from chronic gastritis to low-grade MALToma and in the third between low-grade and high-grade.
We conclude that the presence of bcl-2 protein positive follicles is consistent with both a follicular and extrafollicular origin of a B lymphoma of MALT.
However, the detection of a bcl-2 gene rearrangement is the most valuable criterion in such a situation, and additional immunophenotypic criteria, such as CD10 expression and lack of vimentin within the neoplastic population, further substantiate the diagnosis of a follicular lymphoma in MALT.
However, the detection of a bcl-2 gene rearrangement is the most valuable criterion in such a situation, and additional immunophenotypic criteria, such as CD10 expression and lack of vimentin within the neoplastic population, further substantiate the diagnosis of a follicular lymphoma in MALT.
Our results suggest that p53 partial inactivation may play an important role in the development of low-grade MALT lymphomas, whereas complete inactivation may be associated with high-grade transformation.
In this study, we have examined the frequency of replication error (RER+) phenotype, a newly defined manifestation of genetic instability, and its relationship to p53 mutations in 40 MALT lymphomas (16 high grade and 24 low grade).
The presence of clonal IgH gene rearrangement in CAG-Hp supports the hypothesis that H pylori is involved in the pathogenesis of low grade gastric B-cell MALT lymphomas.
Gastric lymphoepithelioma-like carcinoma and jejunal B-cell MALT lymphoma with large cell transformation. Demonstration of EBV with identical LMP gene deletions in the carcinoma and large cell lymphoma.
To determine whether p53 mutations were also present in MALT lymphoma, we evaluated specimens from eight patients (six gastric specimens, one parotid, and one from the small bowel) for p53 mutations using polymerase chain reaction and single strand conformational polymorphism analysis.
The polymerase chain reaction (PCR) with polyacrylamide gel electrophoresis was used to study patterns of immunoglobulin heavy chain (IgH) gene rearrangement (GR) in formalin-fixed, paraffin-embedded specimens of lymphomas and reactive conditions of mucosa-associated lymphoid tissue (MALT) and lymph node.
The highest rate of p16 gene methylation in tumors was found among MALT (mucosa-associated lymphoid tissue) lymphomas in which the percentage of cases with p16 gene methylation reached 67%.