Immunohistochemical Evaluation of GFAP in Salivary Gland Tumors.

The present study deals with the immunohistochemical evaluation of glial fibrillary acidic protein (GFAP) in salivary gland tumors and the results are compared with vimentin, cytokeratin (K8.12) and S100 protein. In normal tissue from tumors of the salivary gland, the myoepithelium did not express GFAP. In glandular tissues adjacent to tumor or invaded by carcinoma, GFAP was detected in flattened and spindle shaped cells that surrounded intercalated ducts and atrophic acinar structures. In pleomorphic adenoma, the nonluminal cells in tubulo-ductal structures and modified or neoplastic myoepithelial cells which formed solid, myxoid and chondroid structures showed intense immunoreactivity for GFAP. GFAP was also detected in basally located tumor cells in adenoid cystic carcinoma and papillary-cystadenocarcinomas. Those cells corresponding to the GFAP positive cells were also positive for vimentin, cytokeratin (K8.12) and S100 protein. The results of the present study allow us to suggest that the salivary gland tumors may originate from basal cells of intercalated ducts and the basal cells may be closely related with neural ectoderm.