(2) p53 gene deletion was found in 31.0% of patients with primary gastrointestinal MALT lymphoma; p53 gene deletion was found in 22.6 % of patients with primary gastrointestinal MALT lymphoma at stage I-II and in 54.5% of patients at stage III-IV (χ(2) = 3.882, p < 0.05).
We investigated p53 immunoreactivity, mutations of the K-ras gene, and MSI in 27 gastric marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue type (MZBCL) and 24 diffuse large B-cell lymphomas (DLBCL). p53 immunoreactivity was examined using a monoclonal antibody, DO-7.
Helicobacter pylori eradication therapy for high-grade mucosa-associated lymphoid tissue lymphomas of the stomach with analysis of p53 and K-ras alteration and microsatellite instability.
Lymphomas of the ocular adnexa represent approximately eight percent of all extranodal lymphomas, most of which are MALT lymphomas, but few studies had explored the alterations of BCL-1, BCL-2, c-MYC and p53 genes specifically for ocular MALT lymphomas.
In contrast, the 10 EBV-positive cases, none of MALT type, had a much higher rate of mutation, and all showed both p53 overexpression and p53 mutation and/or LOH, and 87.5% had mutations involving exon 7.
Analyzing exons 5-9, we have found mutations in the p53 gene in 7 of 94 cases distributed in different subtypes: 4/12 (33%) high-grade B-cell non-Hodgkin's lymphomas (B-NHLs), in 1 of 5 (20%) high-grade mucosa-associated lymphomas (MALT), in 1 of 22 (4.5%) anaplastic large cell lymphoma (ALCL), and in 1 of 24 (4%) T-cell NHLs.
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).
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.
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.