The Value of Immunohistochemical Markers in Pleomorphic Adenoma and Adenoid Cystic Carcinoma of the Salivary Gland

Background: In recent years, immunohistochemical markers have provided considerable contribution to salivary gland tumor diagnosis and classification. The aim of this study was to evaluate diagnostic value of various cytokeratin markers and smooth muscle actin (SMA) in differential diagnosis of pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC). Methods: In this retrospective study, 35 cases of salivary gland tumors composed of 19 PA and 16 ACC were selected and immunohistochemical staining with six cytokeratin markers (CK7, CK8, CK13, CK14, CK17 and CK18) and SMA were performed. The positivity of these markers in both typical and atypical areas of each tumor was compared. Positivity was defined if 10% or more of the cells were immunostained. Results: In the PA group, there was no difference between luminal and stromal expression of CK7, CK 8, CK 13, CK 14, CK 17, and CK 18 in both typical and atypical areas except SMA that was not expressed in the atypical area. No statistically significant differences were found between the expression of CK7, CK 8, CK 14 and CK 18 in both typical and atypical areas of ACC group, with no expression of SMA in atypical area. Conclusion: It seems that the immunoprofile of the atypical area of both PA and ACC are similar to each other and IHC does not help to differentiate them.