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Growth pattern and differentiation of human soft tissue sarcomas in nude mice

Tumor suspensions prepared from 62 human soft tissue sarcomas were injected into the peritoneal cavity and subcutis of 124 nude mice. The sarcomas included were ten malignant fibrous histiocytomas, 15 fibrosarcomas, six tendosynovial sarcomas, five liposarcomas, nine myosarcomas, six angiosarcomas, six malignant schwannomas, and five miscellaneous sarcomas. Sixty‐two percent of the sarcomas showed progressive growth in nude mice either subcutaneously (46%), intraperitoneally (14%), or at both sites (40%). Fifty‐one percent of the primary sarcomas, 71% of the recurrent tumors, and 78% of the sarcomas that were metastatic grew in the animals. Sarcomas that were grafted into the subcutis appeared as solitary nodules and showed a more accelerated growth as well as better differentiation than those that were injected into the peritoneal cavity. The intraperitoneal tumors were multifocal and dedifferentiated growths. It appears that simultaneous subcutaneous and intraperitoneal grafting of human sarcomas into nude mice offers a model to study the histogenesis and morphologic variations of soft tissue sarcomas.