Abstract
BACKGROUND: To investigate the clinical imaging manifestations, diagnosis and treatment of intraperitoneal extraosseous osteosarcoma. CASE PRESENTATION: A 52-year-old male patient with intraperitoneal extraosseous osteosarcoma was retrospectively analyzed. He suffered from left lower abdominal pain accompanied by mass for 6 months. On abdominal CT scan, multiple patchy and banded calcification were found. The largest is about six centimeters in diameter and underwent mass resection. Postoperative pathology revealed retroperitoneal osteosarcoma. The reported intraperitoneal extraosseous osteosarcoma was analyzed and the related literature was reviewed. Two years after operation, the patients had recurrence of the tumors and invaded sigmoid colon, peritoneum and bladder. Palliative operation was performed to remove the tumors in the bladder and transverse colostomy was performed. The patients were followed up by telephone and died 2 months after the second operation. CONCLUSIONS: Intraperitoneal extraosseous osteosarcoma has a low incidence and has no specific imaging features. Surgical resection is the main treatment and the prognosis is poor.