Cytoskeletal proteins in oncocytic tumors of the parotid gland.

Oncocytomas and Warthin's tumors were studied ultrastructurally and with immunofluorescence microscopic techniques against cytokeratins, desmin, vimentin, and actin, the latter characterizing myoepithelial cells. The cell types were found within oncocytomas, one type packed with mitochondria and virtually without filaments, the other contained fewer mitochondria but large amounts of cytokeratins. In Warthin's tumors, all cells contained cytokeratins, the basal cell to a much higher degree. No tumor cells contained vimentin or desmin. Actin was found only close to the apical cell surface in the cylindrical cells in the Warthin's tumors and around the few acinar lumina found in the oncocytomas; thus, a myoepithelial origin of oncocytic tumors of salivary glands seems less plausible. The similarity in staining pattern, namely the pronounced dimorphism of both tumor types, indicates a common progenitor of oncocytomas and the epithelial component in adenolymphomas.