Extraskeletal osteosarcoma infiltrating pancreas, spleen, gastric, and left kidney: a case report.

Background: Extraskeletal osteosarcoma is an extremely rare malignancy that accounts for 1% of soft tissue sarcoma and 4.3% of all osteosarcoma. Extraskeletal osteosarcoma can develop in a patient between the ages of 48 and 60 years.