Extraosseous osteosarcoma presenting with intestinal hemorrhage: case report and literature review.

A 23-year-old man presented with intestinal bleeding due to an extraosseous osteosarcoma of the jejunum. A lesion was also found in the deltoid muscle, and other metachronous soft tissue sites developed subsequently. The presence of malignant osteoid was documented by immunohistochemical studies of one of the lesions. The patient died of metastatic disease 19 months after diagnosis, despite surgical resections and adjuvant chemotherapy. This unique presentation is discussed, and the literature concerning extraosseous osteosarcoma is reviewed.