Immunohistochemical assessment of the OVOL1 in pleomorphic adenoma and its malignant counterpart Key word OVOL1 Pleomorphic adenoma Carcinoma x pleomorphic adenoma

Background Pleomorphic adenoma (PA) is one of the few benign salivary gland tumors (SGT) that can undergo malignant change. Accordingly, a detailed study of the OVOL1 in PA and carcinoma x pleomorphic adenoma (CXPA) would be expected to contribute to the basic explanation of the mechanisms underlying the development of benign and malignant PA diagnosis for better evaluation of tumor biologic behavior. Method This retrospective study included 40 eligible cases (20 cases of PA and 20 cases of CXPA). The medical electronic records of patients were collected. Data regarding age, gender, tumor size, lymph node status, and TNM staging. Re-examination and revision of hematoxylin and eosin (H&E) stained slides were performed by expert pathologists. The OVOL1 immunostaining was used to differentiate between PA and CXPA. Results The OVOL1 level was higher significantly in PA lesions compared to CXPA. Conclusion OVOL1 down-expression may be contributing to the progression of PA to CXPA, which may provide a marker for malignant potentiality in PA and CXPA.