Pleomorphic adenoma: does the immunohistochemical profile direct the clinical profile: retrospective study and review of literature

BACKGROUND: Pleomorphic adenoma is a benign salivary gland tumor that has a potentiality to recurrence and malignant transformation as well. The genetic alteration of this tumor is not completely studied yet. Investigating the growth factor receptors and tumor microenvironment may yield answers to the nature of this tumor. METHODS: Thirty-six formalin-fixed, paraffin-embedded pleomorphic adenoma specimens were collected from Al-Mouassat University Hospital. EGFR, HER-2 and BCL-2 antibodies have been used in immunohistochemistry stains to investigate the most probable affected pathway in this progress of this tumor. RESULTS: Immunohistochemical analysis revealed total negativity for HER2 expression. While, EGFR and BCL-2 expression was positive in diffuse patchy pattern. The positivity was membranous and/or cytoplasmic predominantly within the tumor cell population. Statistical analysis revealed no significant association between EGFR/BCL-2 expression and patient gender (p = 0.848) or tumor site (p = 1.000). The absence of HER2 expression was consistent across all cases, regardless of clinicopathological parameters. The expression of EGFR and BCL2 did not show a statistically significant correlation with demographic variables, suggesting a tumor-intrinsic expression pattern rather than dependence on clinical factors. CONCLUSION: On this study, pleomorphic adenoma demonstrated a distinct immune-profile with positivity of EGFR and BCL-2 and negative expression of HER-2. These findings suggest HER-2 unlikely contribute to tumor behavior, meanwhile the positivity of EGFR and BCL-2 may be related to the tumor survival rather than malignant transformation. Moreover, these markers do not same to consider as reliable predictors of malignant transformation in pleomorphic adenoma.