Immunohistochemical analysis of P53 and bcl-2 in benign and malignant salivary glands tumors

Background: Salivary glands tumors are relatively uncommon neoplasm with widely variable histopathologic and biologic characteristics. Alteration in some proto-oncogenes and tumor suppressor genes may lead to the development and progression of these tumors. Aims: The purpose of this study was to analyze the immunohistochemical expression of P-53 and bcl-2 in some salivary gland tumors in relation to tumor size, histologic grade, and extent of invasion. Setting and design: The sample consisted of 22 formalin-fixed paraffin embedded blocks of benign and malignant salivary glands tumors. Material and method: P-53 and bcl-2 immunoreactivity was semi-quantitatively evaluated in at least 1000 cells examined under the microscope at 40x magnification and recorded as percentage of P-53 or bcl-2 positive tumor cells over the total number of cells examined in the same area. Percentage scores were subsequently categorized using the 5% cut-off point for positive staining. Results and conclusion: Pleomorphic adenoma (PA) showed negative expression of P-53 and bcl-2 in 70% of cases, whereas all malignant salivary glands tumors were positive for P-53 and bcl-2. P-53 positive/bcl-2 positive immunostaining reaction was week in small size PA and was totally absent in larger lesions. However, all malignant tumors expressed P-53, with the highest record in low-grade adenocarcinoma (76%) and the lowest score was observed in both low-grade carcinoma in PA and adenocystic carcinoma. bcl-2 immunostaining was also assessed, the highest recorded score was in high-grade adeno cystic carcinoma (90%) and the lowest in both low-grade carcinoma ex-PA and low-grade cystic mucoepidermoid carcinoma (3%). P-53/bcl-2 immunostaining reactivity could be helpful in demonstrating salivary glands tumor behavior in terms of progression and extent of invasion.