Benign and malignant fibrous histiocytomas of the soft tissues. Functional characterization of the cultured cells

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Abstract
Cell cultures were carried out from fresh tumor tissues obtained from seven cases of histiocytic tumors of the soft tissues including four of malignant fibrous histiocytoma, two of benign fibrous histiocytoma, and one of giant cell tumor of tendon sheath. The cultured cells were studied by light and electron microscopy, rosette formation for surface receptors, immune phagocytosis, and enzyme cytochemistry. The culture of each tumor revealed a mixture of histiocyte‐like cells, fibroblast‐like cells, and intermediate forms. Bizarre giant cells were numerous in the early cultures of malignant fibrous histiocytoma, but they were absent in the cultures of benign fibrous histiocytoma and giant cell tumor of tendon sheath. In all the seven cases the cultured cells exhibited several features characteristic of histiocytes: (1) surface receptors for the Fc‐portion of immunoglobulin G; (2) surface receptors for the third component of complement; (3) immune phagocytosis of opsonized erythrocytes; and (4) lysosomal enzymes including α‐naphthyl butyrate esterase, and acid phosphatase. These findings suggest that the histiocytic tumors of the soft tissues in discussion actually comprise the cells that have the functional property of histiocyte. The tumor cells in the surgical specimens presented essentially the same ultrastructural and enzyme histochemical characteristics as those of the cultured cells.