[Cytoplasmic filaments in the electron microscopy diagnosis of sarcomas]

The ultrastructure of cytoplasmic filamentous material in cells of different human sarcomas was studied and several types of it are distinguished. The first type is specific and can be used as a differential diagnostic marker of tissue appurtenance of neoplasias: in fibroasarcoma cells--a uniform layer of thin filaments located near the plasmic membrane; in rhabdomyosarcomas--thick sheets of long filaments; in leiomyosarcomas--bundles of filaments with focal consolidation; in liposarcomas--loosely packed scarce layers of thin filaments of cylindrical shape; in malignant synoviomas--rod-shaped bundles of thin filaments, endotheliomas--thick single bundles of predominantly perinuclear location. Two types of nonspecific filamentous apparatus in cells of these neoplasias were distinguished: widelooped loose filamentous network and thick circular sheets. The problems of genesis and formation of filamentous apparatus of different types in tumor cells are discussed.