Immunohistochemical study of the expression of fatty acid synthase and Ki‐67 in salivary gland tumors

J Oral Pathol Med (2010) 40 : 467–475 Background: The enzyme fatty acid synthase plays a fundamental role in the biosynthesis of fatty acids. Several recent studies have demonstrated a high fatty acid synthase expression in malignant tumors. Few studies have been conducted in oral and salivary gland tumors describing the fatty acid synthase expression. Methods: This study evaluated and compared, by immunohistochemical reaction, the expression of fatty acid synthase and Ki‐67 in salivary gland tumors. The immunohistochemical study used the streptavidin–biotin–peroxidase technique, with antibodies anti‐fatty acid synthase and anti‐Ki‐67. The fatty acid synthase was analyzed by scores, considering the intensity of labeling, quantity of labeled cells and histological component. The Ki‐67 was analyzed by counting of one thousand cells, calculating the quantity of positive cells in regions with higher density of labeling. Statistical analysis was performed using the Pearson and Mann–Whitney correlation tests. Results: There was greater fatty acid synthase expression in pleomorphic adenoma compared to other tumors, and predominance of Ki‐67 in malignant tumors. Among these, the mucoepidermoid carcinoma presented the highest proliferation rate. The expression of fatty acid synthase and Ki‐67 did not present correlation between the tumors analyzed, except in pleomorphic adenomas, with statistically significant relationship between them. Conclusion: It is suggested that the fat metabolism in salivary gland tumors is related to maintenance of cell differentiation. Its expression prevailed in benign tumors, while Ki‐67 prevailed in the mucoepidermoid carcinoma, demonstrating its high proliferation rate, followed by the cystic adenoid carcinoma and polymorphous low grade adenocarcinoma.