Immunohistochemical study of the distribution of endogenous biotin and biotin-binding enzymes in ductal structures of salivary gland tumours

To clarify the pathologic Value of endogenous biotin in the salivary gland, we examined in a series of neoplasms of the salivary gland by immunohistoc hemical staining the distribution of endogenous biotin and of biotin-bindin g enzymes, namely, acetyl CoA carboxylase (AC), which is a cytosolic enzyme , and pyruvate carboxylase (PC), which is a mitochondrial enzyme. In pleomo rphic adenoma, we found biotin and PC in ductal epithelial elements, while AC was found mainly in myoepithelial elements. Carcinoma ex pleomorphic ade noma, adenocarcinoma and mucoepidermoid carcinoma were frequently immunopos itive for biotin, PC and AC, while adenoid cystic carcinoma was rarely immu nopositive for biotin, PC or AC. These results indicate that endogenous bio tin might be associated with the mitochondrial enzyme, which is present at high levels in ductal cells of the salivary gland. However, the neoplastic cells in adenoid cystic carcinoma seemed to have an unusual expression of b iotin and related enzymes.