الفهرس 
materials and methodsOnly 14 pages are availabe for public view
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Abstract
Gastric mucosa associated lymphoid tissue (MALT) lymphoma may arise from MALT acquired secondary to long standing Helicobacter pylori infection and its development is antigen driven, requiring T cell help. Several cell cycle regulatory genes may play an important role of modulation of cellular death, proliferation and transformation during evolution of H pylori associated gastritis to MALT lymphoma.
The present work aimed at immunohistochemical study of cyclin B1 expression, study of apoptosis determined by TUNEL method and B-cell clonality determined by PCR study.
The material of this study included 80 gastric biopsies (35 cases were chronic active gastritis, 12 cases were gastric MALT and 33 cases were gastric MALT lymphoma). All cases of CAG and MALT were endoscopic biopsies and were H pylori positive while 14 cases of lymphoma were endoscopic biopsies and the other 19 cases were gastrectomy spicemens.
Lymphoid infiltrate of gastritis were scored according to criteria mentioned by FVotheryaon et at, (1995) into: score I (n=20) and score 2 (n=15) which constituted chronic active gastritis (CAG) and score 3 (n=9) and score 4 (n=3) which constituted gastric MALT. CAG cases were graded according to Updated Sydney Grading System of gastritis (Dixon et al., 1996) into GI (n=14), GII (n=6) and GIII (n=15). The MALT lymphoma cases were graded following criteria proposed by (De Jong et al., 1997) into: LG (60.6%), LG>HG (6.1%), HG>LG (24.2%) and HG (9.1%).
The average age of chronic gastritis cases was 34.7 years and that of MALT
patients was 40 years. The average age of gastric MALT lymphoma cases was 47.9 years. The patients of low grade lymphoma showed female predominance (55% of LG lymphoma were females) while 50% of LG>HG, 62.5% of HG>LG and 66.7% of HG lymphoma were males.
In this study 75% of LG lymphoma cases studied were localized to submucosal layer, 25% had LN metastasis and 75% had lower tumor stage. In comparison, 81.8% of lymphoma cases with high grade component, deeply invaded beyond the submucosa, 54.5% had LN metastasis, and 54.5% were in advanced stage.
All studied gastritis and gastric MALT cases were H pylori positive while H pylori were detected in 70% of low grade lymphoma. In comparison, 50% of LG>HG, 12.5% of HG>LG, and non of HG lymphoma cases showed H
pylori.
H pylori were detected in 63.5% of cases localized to submucosa while were detected in only 9.9% of deeply invaded cases. Also H pylori were present in 12.5% of cases associated with LN metastasis while 45.5% of cases lacking LN metastasis were positive for H pylori. H pylori were found in 67.7% of cases in stage II, in 20% of cases in stage 12 and in only 2.5% of cases in stage III.
As regards cyclin B1 immunostaining results, various numbers of benign and malignant lymphoid cells expressed predominantly cyclin B1 in their cytoplasm and occasionally in their nuclei. Also cyclin B1 staining was detected in both cytoplasma nd nuclei of the normal appearing gastric glandular epithelium.
When compared to chronic gastritis cases, those of gastric MALT and MALT lymphoma had an increase of cyclin B1LI of 2.3 and 3.9 folds respectively. The highest overlapping value between some cases of gastric
MALT and MALT lymphoma was 4.8%.
There was a regional difference in cyclin B ILI of malignant lymphoid cells in the mucosa compared to cells in deeper layer of gastrectomy specimens of MALT lymphomas cases. The mean LI in mucosa was 9.4% while that in deep layers was 62.3%. There was also a difference in intensity of staining of lymphoid cells in different areas of section studied. Malignant cells infiltrate the muscle and serosal layers stained more intensly than other areas. GII and Gill gastritis had higher cyclin B1LI (2.02% and 2.7% respectively) than GI gastritis (cyclin B1LI was 1.75%). Gastric MALT cases (score 3 and 4) had higher LI (3.4% and 4.% respectively) than CAG. There was a significant correlation between cyclin B ILI and mononuclear cell infiltrate but no correlation to the PNL infiltrate, gastric atrophy and intestinal metaplasia.
The mean cycl in B ILI of malignant lymphoid cells in mucosa of low grade lymphoma was 8.1% and in deep layer was 50.4% while in mucosa of LG>HG was 7.95% and in deep layers was 51.5% and in mucosa of HG>LG was 11.9% and in deep layers was 72.7%. in high grade lymphoma the LI was 8.6% in mucosa and in deep layers was 80.7%.
Tumors deeply invaded beyond the submucosa had cyclin BM 76.9% in deep layers while cases localized to submucosa had cyclin B ILI 42.15%. Lymphoma cases associated with LN metastasis had cyclin BI LI 67.1% while cases not associated with LN metastasis had cyclin B1 LI 58.7%. Cases in stage II had cyclin B ILI 43.7%, in stage 12 76.8% and in stage III
67.13%.
The cyclin B I LI of lymphoma cells in deep layers in which H pylori were not detected was 74.8% while that of cases positive for H pylori was 35.2%. The apoptotic index (AI) was 0.37% in CAG, 1.26% in gastric MALT and
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Summary and Conclusion
0.9% in gastric MALT lymphoma cases. The density of mononuclear cell infiltarte was significantly correlated with AI while no correlation was found between AI and PNL infiltrate, gastric atrophy and intestinal metaplasia. High grade lymphomas showed significant increased AI compared to low grade lymphoma (1.33% and 0.61% respectively).
AI of malignant lymphoid cells of lymphoma cases localized to SM was 0.7% while that of cases deeply invaded beyond the submucosa was 1.4%. no significant difference was found between AI to H pylori, LN metastasis or staging of lymphoma cases.
There was a high significant inverse correlation between AI and cyclin B I LI in H pylori associated gastric MALT and MALT lymphoma of endoscopic biopsies. The mean cyclin B1 LI of MALT cases was 3.72% and Al was 1.26% while in H pylon positive gastric MALT lymphoma of endoscopic biopsies the mean cyclin B ILI was 7.7% and AI was 0.59%.
A significant correlation was found between cyclin B I LI of lymphoid cells in deep layers beyond the mucosa and AI in relation to grade of gastric MALT lymphoma.
As regards the PCR results an oligoclonal band was found in one case (6.67%) of score 2 gastritis and monoclonal band in 4 cases (33.3%) of gastric MALT cases. All gastritis cases score 1 showed polyclonal pattern. The clonal bands were often seen against backgroud of a polyclonal smear and were not reproducible from deeper sections.
Oligoclonal bands were detected in 14.3% of MALT lymphoma cases and monoclonal bands with or without background smear in 71.4%. these bands were reproducible from deeper sections. The polyclonal pattern were observed in 14.3% of MALT lymphoma cases.
(1)H pylori is concerned in the initial phase in genesis of gastric MALT lymphoma than with later phase.
(2)Low grade gastric MALT lymphoma is associated with a less aggressive behavior of the tumor (regarding depth of invasion, LN meastasis and the stage) than HG lymphoma.
(3)In the initial stage of lymphoproliferative disease (gastric MALT), the deletion of unwanted and/or the defective lymphocytes (caused by H. pylori infection) might involve down regulation of cyclin 131 gene.
(4)High apoptotic score was encountered in gastric MALT where lymphoid cells are generally activated in response of specific foreign substances and/or pathogens (H. pylori) and undergo several successive rounds of cell division over a peroid of several days so the status of the -- lymphoid cells (resting or activated lymphocytes) may be one crucial factor for induction of apoptosis
(5)High labeling score (>4.8%) of cyclin B1 in conjunction with low labeling index (0.76%) of apoptosis in H pylori associated gastric MALT may help in identifying the population that primed to develop MALT lymphoma.
(6)Genetic change such as cyclin BI overexpression may included in H.pylori independent gastric lymphoma or high grade transformation.
(7)Cyclin B1 overexpression in gastric MALT lymphoma is associated with more aggressive biological behavior of the disease.
(8)Diagnosis of low grade MALT lymphoma in endoscopic biopsies is often difficult as the biopsies are small and superficial and may not permit evaluation of the well defined histological criteria. To improve diagnostic
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Summary and Conclusion
accuracy, the use of large biopsy, or obtaining large number of biopsies is recommended. Immunohistochemistry and molecular analysis are useful adjuncts.
(9)Detection of a single clear and reproducible band in PCR reaction strongly support the presence of a malignant clone in gastric biopsies.
(10)Gastric MALT lymphoma is antigen driven and H. pylori gastritis is an established risk factor for the development of lymphoma in the stomach. The presence of clonal B-cell would support this link and might identify patients at risk of future development of lymphoma; alternatively these clonal B-cell may represent a stage in the natural history of the disease and may not necessarily mean progression to overt lymphoma.