[Expression of S-100 proteins and intermediate filament proteins in pleomorphic adenoma]

To observe immunohistochemical expression of S-100A1, S-100A2, S-100A4, S-100A6, S-100B, K8.12, KL1, Vimentin, GFAP and NSE in pleomorphic adenoma of salivary gland, and to evaluate the differential localization of S-100 proteins and biological behaviour of neoplastic myoepithelial cells.

23 cases of normal salivary gland and 60 cases of pleomorphic adenoma were embedded, in paraffin and were routinely diagnosed on the basis of hematoxylin and eosin-stained sections. Serial sections at 4 microns from the paraffin embedded blocks were used for the immunohistochemical studies.

Normal salivary glands had positive immunoreactivity for S-100A families, K8.12 and KL1 in the ductal cells, while S100B, GFAP and NSE were observed in peripheral nerve fibers innervating the gland. In pleomorphic adenomas, luminal tumor cells in duct-like structures had positive immunoreactivity for S-100A subfamilies and keratin. Nonluminal tumor cells had positive immunoreactivity for S-100B, as well as Vimentin, keratins detected by monoclonal K8.12 and KL1, GFAP and NSE.

These findings may suggest that the neoplastic myoepithelial cells contain Ca2+ binding proteins which may have a role in the regulation of calcium ions or calcium signaling mechanisms in the modulation of extracellular matrix deposition in pleomorphic adenoma which may in turn affect the extracellular matrix synthesis as well as histomorphology of the tumor.