Immunohistochemical demonstration of desmin in canine smooth muscle tumors.

Sections of formalin-fixed, paraffin-embedded canine leiomyomas, leiomyosarcomas, or fibrosarcomas were examined by immunohistochemical methods for the presence of desmin. Twenty-two leiomyomas and leiomyosarcomas were stained using the avidin-biotin complex technique, and 14 samples demonstrated positive staining for desmin. The eight negative results obtained may reflect differences in fixation or the affinity of the primary antibody for the tissues examined. Desmin was specific for myogenic tissues. Five canine fibrosarcomas examined immunohistochemically were all negative for desmin staining. The results indicate that desmin is a useful marker for immunohistochemical identification of canine leiomyomas and leiomyosarcomas.