immunohistochemical analysis of b-cell lymphoma -2 in pleomorphic adenoma and mucoepidermoid carcinoma

background: salivary gland tumors form a major area in the field of oral pathology. b-cell lymphoma -2 (bcl-2) is an anti-apoptotic gene with up-regulation in various neoplasms. the aim of the present case-control study was to comparatively investigate the expression of bcl-2 protein in pleomorphic adenoma (pa) and mucoepidermoid carcinoma (mec) and assess its potential diagnostic role in differentiating these tumors. materials and methods: a total of 28 cases (18 specimens of pa [control] and 10 blocks of mec [case]) were selected for analysis by streptavidin-biotin peroxidase method with antibody against bcl-2. the percentage of positive cells was calculated from a minimum of 1000 neoplastic cells and h-score was identified (% positive cells × intensity of staining). data were analyzed using two-way anova, t -test, spearman, chi-square and fisher tests (α = 0.05). results: bcl-2 expression was shown in 13 cases (71%) of pa and 3 cases (30%) of mec. in addition, four cases of pa showed strong staining. there was a significant difference between the expression intensity of bcl-2 in the two tumors ( p = 0.048) according to anova. no correlation was observed between bcl-2 expression with the size and location of tumors ( p > 0.05). conclusion: bcl-2 expression might be used for differentiating these tumors. bcl-2 protein was overexpressed in pa compared with mec. hence, it seems that unlike what was observed in pa, bcl-2 probably does not participate in the pathogenesis of mec. key words: b-cell lymphoma-2, mucoepidermoid carcinoma, pleomorphic adenoma, salivary gland tumor