Immunohistochemical Detection of Proliferative Marker Ki-67 in Benign and Malignant Salivary Gland Tumors

Abstract

Introduction: Salivary gland tumors are the most histologically heterogeneous group of tumors with the greatest diversity of morphologic features among their cells and tissues. The present study was aimed at assessing the validity of Ki-67, a cell proliferation marker, as a prognostic factor in benign and malignant salivary gland tumors and to study whether it is related to age, sex, anatomical site, and size of the lesion in salivary gland tumors. Materials and methods: A retrospective study consisted of benign salivary gland tumors (BSGTs) (n = 15), malignant salivary gland tumors (n = 18), and normal salivary gland parenchyma (n = 15). Results: There was a significant difference of Ki-67 labeling index (LI, %) in normal salivary gland parenchyma, BSGTs, and malignant salivary gland tumors. The Ki-67 LI (%) in normal salivary gland parenchyma is negligible (0.27 ± 0.31%), whereas malignant salivary gland tumors showed very high Ki-67 LI (%) of 18.79 ± 18.06% compared with BSGTs being 0.76 ± 2.02%. There was a significant correlation statistically of mean ± standard deviation (SD) of Ki-67 LI (%) with the age of the patients being the maximum (32.68 ± 15.87%) in the 50 to 59 years age group, whereas sex, site of the lesion, and size of the lesion in salivary gland tumors had no significant correlation. Conclusion: The Ki-67 is a useful marker for assessing prolif-erative potential of tumors. Clinical significance: The Ki-67 LI% can be used as a reliable adjuvant diagnostic tool to differentiate between the subtypes and grading of certain malignant tumors, such as mucoepi-dermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), and acinic cell carcinoma (AcCC), which are usually difficult to diagnose on histopathological criteria alone. Keywords: Immunohistochemistry, Ki-67, Salivary gland neoplasms.