Expression of intermediate filaments and stromal proteins in granular cell tumor of the tongue.

Intermediate filament subunits as well as components of the extracellular matrix, were localized in three cases of granular cell tumor of the tongue. Of the five intermediate filament families, only vimentin was present within the tumor cells. No labeling was obtained with antibodies to cytokeratin, desmin, neurofilaments, and glial filaments; this suggests that this tumor is not derived from epithelium, muscle, neural, or astrocytic origins, respectively. Immunofluorescent staining of the tissue with antibodies to fibronectin and to collagen indicated that the tumor contained low levels of these extracellular matrix proteins. The results suggest the possible use of antibodies to intermediate filaments as histogenetic markers for the clarification of the origin of tumors whose nature cannot be unequivocally determined by conventional histopathologic methods.