Immunomorphological characteristics of pleomorphic adenoma of salivary glands

The immunohistochemical profile of 23 pleomorphic adenomas and 7 normal salivary glands was studied. We used antisera to vimentin (V), desmin (D), epithelial membrane antigen (EMA), prostate specific antigen (PSA), pancytokeratin, carcinoembryonic antigen (CEA), glial fibrillary acidic protein (GFAP) and S-100 protein. In the ducts and myoepithelial cells of normal salivary glands immunopositivity to most of the cytoskeletal proteins, EMA and CEA was observed. GFAP was localized only in cells of striated ducts. Major differences in the expression of various antigens among tubular structures, solid sheets, the myxoid and chondroid in the pleomorphic adenoma were encountered. Appearance of GFAP as a sign of stromal transformation into myxoid and chondroid was detected. Judging from these comparative immunohistochemical characteristics between normal salivary glands and pleomorphic adenomas, we assume that tumour cells originate from the reserve cells of intercalated and striated ducts.