Extraosseous osteogenic sarcoma arising from the retroperitoneum: a case report.

A 44-year-old housewife with a mass in the left upper quadrant of the abdomen was admitted. The tentative diagnosis was cystadenocarcinoma arising from the pancreatic tail, as determined by CT and selective angiography. Excision of the mass with removal of the spleen, pancreatic tail, left renal capsule and surrounding lymphnodes was performed. Photomicroscopic sections revealed proliferation of malignant cells and malignant osteoids. The final diagnosis was osteogenic sarcoma arising from the retroperitoneum. Among the extraosseous osteogenic sarcoma arising from the somatic soft tissue, involvement of the retroperitoneum is rare. Only 12 cases including our own case have been reported as being of retroperitoneal origin. No patient survived for five years and in our patient, there are signs of recurrence one year after the surgery.