Extraskeletal soft tissue osteosarcoma.
D006801:Humans; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D013848:Thigh