The intermediate filament cytoskeleton of various types of human soft tissue
tumors was analyzed by immunofluorescence microscopy with the use of specific
antibodies against cytokeratins,
vimentin, and
desmin, as well as by one- and two-dimensional gel electrophoresis of high-
salt buffer- and
detergent-resistant cytoskeletal preparations. All
leiomyomas as well as a
leiomyosarcoma contained
desmin.
Leiomyomas of both gastrointestinal and uterine derivation and the retroperitoneal
leiomyosarcoma showed strong reaction for
desmin in the smooth muscle cells, but the latter two exhibited also
vimentin staining. In
embryonal rhabdomyosarcomas,
desmin prevailed in the large, apparently well-differentiated rhabdomyoblasts; whereas the smaller, less differentiated
tumor cells preferentially contained
vimentin. Cells of
malignant fibrous histiocytomas were characterized by their content of
vimentin as the only intermediate filament
protein present. In
alveolar soft part sarcoma, a rare
tumor of hitherto unknown histogenesis,
vimentin and
desmin co-existed within the same
tumor cells, indicating, together with chemical determinations, the myogenic derivation of this
neoplasm. The results show that immunologic and biochemical analysis of
proteins associated with the intermediate filament cytoskeleton is a useful adjunct in the diagnosis of diverse
neoplasms, particularly those with equivocal histologic features, and thus
aids in the histogenetic classification of soft tissue
tumors.