Synthesis of elastin by pleomorphic adenomas

Previous morphologic and histochemical studies have documented extracellular elastin and elastic fibers within the matrix of pleomorphic adenomas of the salivary glands. By morphologic criteria, the elastin appeared to be synthesized by the tumor rather than being a consequence of stroma produced in response to the tumor cells. To examine this issue, nine pleomorphic adenomas were studied by immunohistochemistry and in situ hybridization with tropoelastin-specific antibodies and complementary DNAs. Corroborating the previous morphologic studies, immunohistochemistry demonstrated abundant extracellular elastin within the matrix of pleomorphic adenomas. Additionally, both immunohistochemistry and in situ hybridization demonstrated continued synthesis of tropoelastin by the neoplastic cells. Tropoelastin production was seen in neoplastic cells with all morphologies.