Intermediate filaments in smooth muscle tumours.

Antisera to the intermediate filaments vimentin and desmin react with fixed paraffin embedded tissue. Benign uterine myomas contain both classes of filaments. Gastrointestinal "smooth muscle tumours" however often lack desmin even when they appear histologically benign. In the sarcomas examined vimentin was the only class of intermediate filament present. The diagnostic and histogenetic implications of these findings are discussed.