Maspin expression in normal, inflammatory and benign tumors of minor salivary glands
Purpose: Maspin is involved in inhibition of cell motility, invasion and metastasis. Reduction in maspin expression has been associated with malignant progression in epithelial tumors. The purpose of this study was to investigate maspin expression in normal and inflamed minor salivary glands (MSG) and to compare it to benign salivary gland tumors.
Methods: Cases of normal MSG, sialadenitis and benign tumors (pleomorphic adenoma) (10 cases for each category) were immunohistochemically evaluated for maspin expression by "point-counting" morphometry. Positive cytoplasmic or nuclear staining was evaluated on 10 HPF separately for epithelial acinar cells or tumoral solid areas and ductal structures. Results are presented as the mean percentage of positively stained cells from the total number of cells of each type.
Results: The highest mean percentage of positive cells was found in the epithelial cells of solid areas of pleomorphic adenoma (68.6+22.4) and this was significantly different from acinar cells in normal MSG (32.14+24) and sialadenitis (27.8+29.1) (p<0.001). No significant differences in maspin expression were found in all examined cases in regard to the ductal structures (p>0.05).
Conclusion: Maspin expression is present both the acinar and ductal structures of normal MSG. Its expression is upregulated in pleomorphic adenomas, especially in the solid areas, in contrast to what has been previously reported in epithelial malignant tumors. Maspin expression is not influenced by inflammatory changes. This study was supported by the Lepco Fund for Medical Research, School of Dental Medicine, Tel Aviv University.