[Cytogenesis and histogenesis of malignant and semimalignant bone tumors].

Our present knowledge about bone tumors is still in need of a convincing cytohistogenetic concept that would support the adequate differentiation and classification of different tumor types. The modern therapeutic approach must rely on subtle diagnostis using preferably cyto- and histomorphologic criteria. The present study depends on a considerable number of malignant and semimalignant bone tumors which were analysed by several modern investigative methods. Based on these results, we intend to find the answers to some problems of cytogenesis and histogenesis of bone tumors. Comparison and correlation of our findings with the results of other authors is attempted with the objective to propose an overall histogenetic concept of bone tumors in consideration of the known data and hypotheses. Our material comprises 85 malignant and semimalignant bone tumors. The following tumor types are discussed on the basis of cases from our collection (numbers in brackets): "Conventional" highly malignant osteosarcoma (32), parosteal and periosteal osteosarcoma (2), telangiectatic osteosarcoma (2), small cell osteosarcoma (1), small cell sclerosing osteosarcoma (2), histiocytic osteosarcoma (1), Ewing's sarcoma (15), "conventional" chondrosarcoma (7), dedifferentiated chondrosarcoma (2), mesenchymal chondrosarcoma (1), giant cell tumor (12), malignant fibrous histiocytoma of bone (5), fibrosarcoma of bone (3), The results of conventional light and electron microscopy, but also of enzyme histochemistry and autoradiography were included in the definitive classification by both histologic and cytologic criteria. In addition, different collagen types present in the ground substance of these tumors were studied by immunofluorescence microscopy; in anaplastic tumors of high malignancy the intermediate filaments of the cytoskeleton were further subjected to immunohistochemical analysis. The concept resulting from these studies may be briefly summarized as follows: The stem cell of conventional, highly malignant osteosarcoma is a stromal cell of the skeletal system, which is undergoing neoplastic transformation. At first this cell fails to show any sign of collagen synthesis, the activity of alkaline phosphatase is not increased. Of a primarily anaplastic nature, this tumor cell may differentiate in several directions: in osteoblastic differentiation, the cell will produce predominantly collagen type I, and alkaline phosphatase activity will increase. During fibroblastic differentiation we observe an increased synthesis of collagen type III, but alkaline phosphatase activity is not raised.(ABSTRACT TRUNCATED AT 400 WORDS)