Intermediate filament proteins in spindle cell carcinoma of the larynx and tongue.

In an analysis of intermediate filament protein expression of spindle cell carcinoma, a variant of squamous cell carcinoma, occurring in larynx and tongue, vimentin positivity was found in sarcomatoid areas in 12 of 13 patients. Scattered expression of keratin was observed in sarcomatoid areas in tumours of 10 patients. However, large parts of sarcomatoid areas of such tumours were negative for keratin. Overlying dysplastic epithelium and squamous cell carcinoma components were positive for keratin. In a number of cases there was a strong indication of co-expression of keratin and vimentin in parts of cells that, on histological grounds, belong to sarcomatoid areas or to cells in the interface between carcinoma and spindle cell area. The use of keratin and vimentin type intermediate filament antibodies could be of great help for the correct classification of these tumours.