الفهرس 
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Abstract
Salivary gland tumors are relatively uncommon representing approximately 1% of all neoplasms in the whole body. These neoplasms are composed of diverse group of tumors with variable histological pictures and different biological behaviors.
Integrins are the first identified member of extracellular matrix receptors. They are transmembrane proteins expressed by all cells and are responsible for mediating the adhesive interactions of cells with ECM macromolecules, thus providing a linkage between the cell cytoskeleton and the extracellular environment. Integrins are down- regulated in some cancer and considered as tumor suppressors. On the contrary, they are over- expressed in other cancer and are reported to be tumor promotors.
The integrin β6, a member of the integrins family, is an epitheial- specific fibronectin, tenascin and osteopontin receptor, whose expression is restricted to epithelial cells. This molecule is usually rarely detected or undetectable in adult healthy epithelia except for rare specific epithelial processes including tumorigenesis. Its detection has been linked with cell differentiation, proliferation, apoptosis, invasion, survival and gene expression.
The aim of this research was to evaluate the immunohistochemical localization of the Integrin β6 in normal salivary tissue, as well as in different histological patterns of benign and malignant salivary gland tumors.
Thirty- eight cases of salivary gland tumors were included in this study. The biopsies were histologically examined after hematoxylin and eosin staining. Clinical data of these cases were collected. The sample included thirteen cases of benign salivary gland tumors (six cases of pleomorphic adenoma, four cases of Warthin’s tumors, two cases of myoepithelioma, one case of basal cell adenoma), and twenty- five cases of malignant salivary gland tumors (seven cases of adenoid cystic carcinoma, five cases of mucoepidermoid carcinoma, three cases of carcinoma ex pleomorphic adenoma, two cases of each of acinic cell carcinoma, salivary ductal carcinoma, myoepithelial carcinoma, polymorphous low- grade adenocarcinoma, and one case of each of epithelial myoepithelial carcinoma and papillary cystadenocarcinoma.
The malignant tumors (65.8 %) were more common than the benign tumors (34.2%), the most common salivary gland tumor was the adenoid cystic carcinoma, representing 18.4%. Pleomorphic adenoma came second in order representing 15.8%. And mucoepidermoid carcinoma came third in order representing 13.2%. The median age for patients in this work was 46.4 (with a range of 18-81 y). Out of 38 cases, 57.9% were males and 42.1% were females. As regards to location, the parotid gland (44.7%) was the most common site followed by the palate (34.2%). A case of recurrence in the submandibular gland was included in this study.
The immunohistochemical detection of the Integrin β6 revealed positive β6 expression in all benign and malignant tumors with different intensities. Normal salivary gland tissue showed negative immunoreactivity for β6, except for weak positivity in few sporadic ductal epithelial cells.
The intensity of immunostaining of Integrin β6 between benign and malignant salivary gland tumors was calculated. There was a statistically significant difference (P < 0.05) in the MOD, which was significantly higher (69.66) in malignant than in benign (27.58) salivary gland tumors. The difference in MA% between these two groups was also highly significant in malignant (68.54) more than in benign tumors (27.38).
Malignant salivary gland tumors showed an intense Integrin β6 expression in all cases. Meanwhile, high- grade salivary gland tumors exhibited a strong immunoreactivity more than the low- grade tumors.