Extraskeletal osteosarcoma: spectrum of imaging findings

The purpose of this article is to present the spectrum of imaging findings of primary and metastatic extraskeletal osteosarcoma and highlight the differences from primary osteogenic osteosarcoma in bone. Extraskeletal osteosarcoma is a rare mesenchymal malignancy of soft tissue, histologically indistinguishable from primary osteosarcoma of bone. However, there are distinct differences in demographics, imaging features, prognosis, and management compared with osteogenic osteosarcoma. Imaging characteristics reflect tumor morphology, with only 50% of primary tumors showing mineralization. Metastases may or may not show mineralization, even if present in the primary tumor. The overall prognosis is poor.