Density of mast cells and microvessels in minor salivary gland tumors.

The aim of this study was to investigate the density of mast cells and microvessels in minor salivary gland tumors. Forty-one cases of minor salivary gland tumors (pleomorphic adenoma, n = 10; adenoid cystic carcinoma, n = 11; mucoepidermoid carcinoma, n = 10; and polymorphous low-grade adenocarcinoma) were investigated using immunohistochemistry for mast cell tryptase and von-Willebrand factor. Density of mast cells was higher in mucoepidermoid carcinoma; however, no differences in the number of these cells were observed between the different types of tumors (p > 0.05). The number of mast cells was higher in periparenchymal areas in all tumors, but the difference was not significant (p > 0.05). Mucoepidermoid carcinoma showed the largest number of periparenchymal mast cells, whereas pleomorphic adenomas showed the smallest number of intraparenchymal mast cells (p > 0.05). The highest microvessel density was observed in mucoepidermoid carcinomas, being this difference statistically significant when mucoepidermoid carcinoma was compared to pleomorphic adenoma (p = 0.0034) and polymorphous low-grade adenocarcinoma (p = 0.004). Microvessel density was significantly higher in adenoid cystic carcinoma when compared to pleomorphic adenoma (p = 0.0406) and polymorphous low-grade adenocarcinoma (p = 0.0123). Comparison of mast cells and microvessel densities showed no significant difference between tumors. A quantitative difference in mast cells and microvessels was observed, particularly in mucoepidermoid carcinoma, a finding supporting the aggressive behavior of malignant salivary gland tumors without myoepithelial differentiation. Further studies are needed to determine the role of mast cells in angiogenesis, as well as in the development and biological behavior of these tumors.