Immunohistochemical localization of the α and β subunits of S-100 protein in pleomorphic adenoma of the salivary glands

Summary

The immunohistochemical expression of the α andβ subunits of S-100 protein in reactive, modified and transformed of myoepithelial cells, salivary pleomorphic was investigated using monoclonal antibodies. With S-100 α, normal salivary glands showed strong staining in serous acinar cells and moderate to slight staining in ductal segments, and with S-100β staining was slight or negative in acinar cells, but strong in nerve fibres. In pleomorphic salivary adenomas, the immunohistochemical distribution of S-100 α andβ proteins indicated great variation in the tumour cells. Some neoplastic cells gave similar staining for both S-100 α andβ, others were strongly positive for S-100 α and stained only slightly for S-100 /gb, or vice versa. Yet other cells were positive for S-100 α and negative for S-100β, or vice versa. Pleomorphic salivary adenomas were classified both by histopathological criteria and by their staining pattern for S-100 α andβ proteins. Great heterogeneity in S-100 α andβ protein expression was found in individual tumour cells of both ductal and myoepithelial origin, and no regular pattern was identified.

The cellular origin of salivary pleomorphic adenomas is discussed in terms of S-100 α andβ protein immunohistochemistry. Pleomorphic adenoma cells may be transformed from reserve cells into tumour cells displaying biologic properties of myoepithelial cells, ductal cells, or a mixture of both.