CYTOPLASMIC EXPRESSION OF HER2 IN GASTRIC ADENOCARCINOMA: AN UNUSUAL FINDING.

Aim: To study the prevalence of HER-2 expression in gastric adenocarcinoma and its correlation with Helicobacter pylori.

Method: 50 gastric cancer biopsies were included in the study. Sections were stained with H&E for morphological details and classified into intestinal and diffuse type gastric adenocarcinoma. Loeffler’s methylene blue was used for identification and grading of Helicobacter pylori. Immunohistochemistry for expression of HER2 protein was done. Pattern of staining was noted and scoring was done. Monoclonal mouse Anti-HER2/neu (c-erbB2) clone CB11 was used.

Statistical analysis was done using chi square test and spearman rank correlation coefficient. P ≤ 0.05 was taken as critical level of significance.

Result: Out of 50 cases 9(18%) were intestinal and 41(82%) were diffuse type adenocarcinoma. Helicobacter pylori were seen in 8/9 (88.89%) and 35/41(85.36%) cases of intestinal and diffuse type adenocarcinoma respectively. HER2 positivity was recorded as membranous, membranous + cytoplasmic and cytoplasmic. 55.56% of cases in intestinal and 73.14% in diffuse type adenocarcinoma showed cytoplasmic ± membranous staining. Expression of HER2 scoring was compared with increasing grades of Helicobacter pylori infection, a significant association (P<0.05) but weak correlation was found between Helicobacter pylori and HER2 expression.

Conclusion: HER2 overexpression is significantly associated with Helicobacter pylori however correlation is weak. Predominant cytoplasmic pattern of expression of HER2 in diffuse gastric adenocarcinoma is unusual and needs further investigation.