Immunohistochemical Expression of p53 in Pleomorphic Adenoma and Carcinoma Ex Pleomorphic Adenoma

OBJECTIVE This study aimed to characterize alteration in the immunohistochemical expression of pRb in normal tissue of the salivary gland surrounding pleomorphic adenoma, the tumor cells of pleomorphic adenomas, and carcinoma arising in pleomorphic adenoma. STUDY DESIGN A selected series of 29 cases of pleomorphic adenomas, and 27 cases of carcinoma ex-pleomorphic adenoma (undifferentiated and adenocarcinoma types) were examined. RESULTS The results showed that pRb expression was negative in the components of normal tissue of the salivary gland surrounding pleomorphic adenoma. PRb expression in pleomorphic adenomas shows that 2 cases out of 29 (6.9%) strongly expressed in the duct cells, 7/29 (24.1%) cases showed moderate staining. pRb nuclear staining in myxochondroid was identified in 10/29 (34.5%) cases of pleomorphic adenomas with weak staining, 6/29 (20.7%) with moderate staining. pRb was strongly expressed in carcinoma cells in 19 out of 27 cases (70.4%). CONCLUSION This study suggests the alteration of pRb expression would increase from pleomorphic adenoma to carcinoma arising in pleomorphic adenomas (6.9% versus 70.4%).