Immunofluorescence of soft-tissue tumors with anti-smooth-muscle and anti-skeletal-muscle antibodies.

One hundred thirteen soft-tissue tumors were studied by immunofluorescence using anti-smooth-muscle (SMA) and anti-skeletal-muscle antibodies (MGA). Of the classic leiomyomas examined, 94% manifested bright fluorescence with SMA, whereas cellular leiomyomas and leiomyosarcomas failed to stain. Of the rhabdomyosarcomas studied, 21% showed fluorescent cross-striations or fluorescent granules after incubation with MGA. None of 48 control tumors fluoresced with either antibody. No tumor vessel seen showed smooth-muscle fluorescence in its walls. Although of little diagnostic value, immunofluorescence utilizing specific human antibodies is a valuable tool with which to study some of the antigenic components of these neoplasms.