Is Gastric MALT Lymphoma Associated with Helicobacter Pylori: An Immunohistochemical and PCR Study
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gastric mucosa associated lymphoid tissue (MALT) lymphomas remain Helicobacter pylon dependent. Aim: This study aims to determine the possible role of B-cell clonality in distinguishing reactive from malignant infiltrate in H. Pylori associated gastritis and MALT lymphoma, the association between cell cycle regulatory protein, cyclin BI, and apoptotic cell death during the progression of MALT lymphoma and to identify protein marker that may help in recognition of the population that at increased risk of developing MALT lymphoma. Materials and Methods: This study carried out on 80 cases of gastric specimens (47 cases were dignosed as chronic gastritis (35 score l&2, 12 cases were score 3&4), and 33 cases are of gastric MALT lymphoma and normal control endoscopic biopsies of stomach were included (N:5), Sections were prepared from formalin fixed paraffin embedded blocks for (1) Haematoxylin and eosin (H&E) stain. (2) Geimsa stain for detection of H. Pylon infection, (3) immunohistochemical staining for detection of cyclin BI overexpression, (4) quantification of apoptic cells using TUNEL, and (5) PCR studies of B cell clonality. Results: In this study the, H. Pylori was detected in chronic gastritis, and in low grade rather than high grade MALT lymphoma. It is also detected in cases localized to submucosa and cases lacking LN metastasis. Cyclin B1 labeling index was higher in MALT lymphoma cases when compared to chronic gastritis cases where cyclin B! LI was 2.3 and 3.4 folds respectively (significant correlation, p<0.01). The mean cyclin B! LI was higher in cases with LN metastasis. There is significant correlation between H. Pylon and cycling B1 LI in MALT cell lymphoma cases with deep layers invasion only, on the other hand, the mean apoptotic index (Al) of chronic gastritis score 3&4 was higher than that of gastritis score l&2 and MALT lymphoma (1.26%, 0.37%, and 0.9% respectively), at the same time it increased in cases with high grade than low grade cases (1.84% and 0.61%) with high significant p value (0.003). No significant correlation was found between Al to H pylon, LN metastasis, or staging of lymphoma cases. There is significant inverse correlation between cyclin BI LI, and Al in H. Pylori associated cases. As regard to PCR results: Oligoclonal bands were detected in 14.3% of MALT lymphoma. and monoclonal bands with or without background smear in 71.4%. the polyclonal pattern were detected in 14.3% of MALT lymphoma cases. Conclusion: These results suggest that cyclin B1 expression may be actively associated in the modulation of cellular death by apoptosis, as well as cellular proliferation and transformation during the evolution of H.pylori-associated gastritis to MALT lymphoma. Also the detection of a single clear and reproducible band by PCR strongly support the presence of a malignant clone in gastric biopsies. Collectively these results may help in recognition of the population that at increased risk of developing MALT lymphoma. Key Words: Gastric mucosa associated lymphoid tissue (MALT) — Helicobacter pylon — Immunohistochernical — PCR Study.