Immunohistochemical demonstration of steroid C‐21 hydroxylase in normal and neoplastic salivary glands

The presence of steroid C‐21 hydroxylase in normal and neoplastic salivary glands was investigated immunohistochemically with the use of antibody against cytochrome P‐450 specific for steroid 21‐hydroxylation (P‐450₂₁). In normal salivary glands, P‐450₂₁ was exclusively present in the excretory duct system (intercalating, striated and large excretory ducts), and not observed in acini. In salivary gland tumors, P–450₂₁ was observed in most epithelial cells of duct origin within pleomorphic adenomas including cells of amorphous groups scattered in myxoid areas, and in adenolymphoma. Some mucous cells in mucoepidermoid tumor also were positive for this enzyme. These findings in the normal and neoplastic salivary gland suggest that the expression of P‐450₂₁ is closely related to ductal differentiation.