Immunohistochemical expression of p16 in pleomorphic salivary adenoma

Objective: This study aimed to characterize alteration in the immunohistochemical expression of p16 in normal tissue of the salivary gland surrounding pleomorphic adenoma, and the tumor cells of pleomorphic adenomas. Material and Method: A selected series of 120 cases of pleomorphic adenomas were examined. Results: The results showed that p16 expression in non tumor duct cells was strong positive nuclear staining in 98 (81.6%) cases out of 120, while there were 20 (16.6%) with moderate staining, and 2 (1.6%) with weak staining in the components of normal tissue of the salivary gland surrounding pleomorphic adenoma. p16 expression in pleomorphic adenomas showed 71 (59.1%) cases with moderate nuclear staining in the duct cells, 45 (37.5%) cases with nuclear weak staining, and 4 (3.3%) cases with negative staining. p16 nuclear staining in myxochondroid tissue was identified in 4 (3.3%) cases with strong staining, 65 (54.1%) cases had moderate staining, and 51 (42.5%) cases had weak staining. Conclusion: This study suggests alteration of p16 expression in pleomorphic adenomas. P16 might have a role in the development of pleomorphic adenoma.