ULTRASTRUCTURAL CYTOCHEMICAL DEMONSTRATION OF ELASTIN IN THE MATRIX OF SALIVARY GLAND TUMORS

Following light microscopic survey of the incidence of elastic tissue in 80 salivary gland tumors, tissue samples from 14 pleomorphic adenomas, three myoepitheliomas, and eight adenoid cystic carcinomas were processed for cytochemical demonstration of elastin with the tannic add stain for ultrathin sections. For comparative study, some other tumor types devoid of elastic tissue at the light microscopic level and non-neoplastic submandibular glands were also investigated. Elastic deposits of varying amounts were clearly revealed on the basal-lamina-like material and/or masses of microfibrils in the matrix close to the neoplastic myoepithelium and, to a lesser degree, immediately beneath the non-neoplastic myoepithelium. None of the other tumor types without myoepithelial differentiation contained elastic deposits closely associated with the neoplastic cells. Intimate topographical relationship of such an immature elastic fiber or developing elastic tissue to the neoplastic myoepithelial cells strongly indicated the primary origin of elastic components from these cells. It is postulated that the potential of salivary tumor cells to produce elastin is regarded as an indicator of their myoepithelial nature or differentiation.