Immunohistochemical demonstration of alpha 1-antichymotrypsin and alpha 1-antitrypsin in salivary gland pleomorphic adenomas of children.

Twenty-five benign pleomorphic adenomas of salivary glands in children were studied with immunohistochemical techniques in order to characterize the cell types comprising the epithelial and so-called "mesenchymal" regions of the tumors. The antisera against alpha 1-antichymotrypsin (alpha 1-ACT) and alpha 1-antitrypsin (alpha 1-AT) were used to stain in normal salivary gland tissue as well as in pleomorphic adenoma. In normal salivary glands, alpha 1-ACT was localized to the intercalated duct and serous acinar cells. On the other hand, there was positive staining for alpha 1-AT in the intercalated and striated duct cells. Twenty-five cases (100%) of pleomorphic adenomas in children displayed positivity to alpha 1-ACT staining and 22 cases (88%) showed a positive staining for alpha 1-AT. alpha 1-ACT staining was particularly intense in chondrocyte-like cells of 20 cases (80%), in inner tubular cells of 16 (64%) and cyst-lining cells of 12 (52%). The limited number of tumor cells which were called plasmatoid or hyaline cells and squamous epithelial cells, were positive for alpha 1-ACT. None of the outer tubular cells and hyalinous material was positively stained for alpha 1-ACT. A strong positive reaction for alpha 1-AT was observed in chondrocyte-like cells of 15 cases (60%). Inner tubular cells were positive for alpha 1-AT in 12 cases (48%), plasmatoid or hyaline cells in 10 (40%) and cyst-lining cells in 8 (35%). Squamous epithelial cells, clear cells, secretory product and hyalinous material were positive for alpha 1-AT in some cases. Chondroid matrix and myxoid stroma had no reaction with both antibodies. The biological role of alpha 1-ACT and alpha 1-AT with a wide immunohistochemical distribution in pleomorphic adenomas of children may be associated with a self regulating mechanism which inhibits degradation by tissue proteinases.