Glycosaminoglycans in pleomorphic adenoma and adenoid cystic carcinoma of the salivary gland

One of the common histopathologic features of pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC) of the salivary gland is the abundant accumulation of glycosaminoglycans (GAGs). To study a relationship between the histologic distribution of GAGs and the morphologic pattern of salivary gland tumors, we carried out immunohistochemical and biochemical analyses of GAGs on 16 cases of PA and three cases of ACC. Immunohistochemically, several GAG fractions such as chondroitin-6-sulfate, unsulfated chondroitin sulfate, and keratan sulfate were seen mainly at the plasma membrane of both PA and ACC cells and of myoepithelial cells of normal salivary glands. Most of these GAG-positive cells were distributed in solid and chondromyxoid parts of PA and in the cellular part of ACC. Biochemical GAG analysis of both PA and ACC, separated into nonsulfated and sulfated fractions by two-dimensional electrophoresis, revealed high concentrations of chondroitin sulfate in both neoplasms, but the concentration of hyaluronic acid, was significantly higher in PA than in ACC. The results show that the concentration of hyaluronic acid, a major nonsulfated GAG fraction, was significantly higher in PA than in ACC and, therefore, this difference may be useful in the differentiation of the two neoplasms.