[A case of retroperitoneal extraosseous osteogenic sarcoma].

A case of primary osteogenic sarcoma in retroperitoneal space is reported. A 33-year-old man was admitted to our hospital with complaints of left flank pain. On examination, a large tumor was found in the left retroperitoneal space. After resection of the tumor, the patient was treated with combined chemotherapy by the regimen of cyclophosphamide, vincristine, adriamycin and dimethyl triazeno-imidazole carboxamide (CYVADIC). He has been well for more than ten months without recurrence. Extraosseous osteogenic sarcoma of the soft tissue is extremely rare, and only 7 cases have been reported in Japan. In general, the prognosis of patients has been very poor with surgery, radiotherapy or chemotherapy alone. A suitable combination chemotherapy or radiotherapy or both following radical surgery should be performed for prolonging survival, and even obtaining a possible cure.