The frequency and distribution of mast cells in pleomorphic adenomas of salivary glands.

Aim: To investigate whether the frequency and distribution of mast cells (MCs) in pleomorphic adenomas (PAs) of major and minor salivary glands justifies the suggestion that there exists an association between MCs and mucoid stromal changes in PAs.

Methods: The material consisted of 22 cases of pleomorphic adenoma (eight arising in major and 14 in minor salivary glands) and a control group represented by five cases of monomorphic adenoma (MA). Representative 3-microm thick, paraffin-embedded sections were stained with H&E and Azur A. Computer-aided image analysis was performed in order to evaluate the relative surface area occupied by epithelial and connective tissue components, as well as the absolute number of MCs.

Results: According to our findings, PAs from minor salivary glands contain significantly greater numbers of mast cells compared with tumours from major glands. Additionally, the distribution of MCs within the stromal connective tissue appeared not to be random.

Conclusion: It is possible that differences in the pattern of connective tissue might influence the actual concentration of MCs and that these differences are responsible for the observed variations between major and minor gland PAs.