Subcutaneous extraskeletal osteosarcoma of the thigh with lymph node and lung metastasis: a case report

Abstract

Background Extraskeletal osteosarcoma (ESOS) is a rare soft tissue tumour which accounts for approximately 1% of soft tissue sarcomas. In particular, subcutaneous osteosarcoma is extremely rare, occurring in less than 10% of ESOS cases. 1 Case report The case of a 71-year-old-woman with a 30-mm mass arising in the subcutaneous tissue of the thigh is presented. Radiological investigations showed spotty calcification in the mass without any attachment to the underlying bone. Wide surgical excision was performed. Microscopic examination revealed a pleomorphic spindle cell neoplasia with abnormal osteoid, some with ossification. It confirmed the diagnosis of subcutaneous ESOS with extension to the dermis and one lateral subcutaneous margin. Radiotherapy was commenced after a wide re-excision. Five months after the primary surgery, she developed metas-tases to the ipsilateral inguinal and pelvic lymph nodes and 5 months later she was diagnosed with inoperable pulmonary metastasis. Unfortunately she died 25 months after her first presentation. Discussion ESOS has been most often described in the deep soft tissues of the extremities. Subcutaneous tissue as a primary site is rare. This case emphasises the poor prognosis in patients with ESOS and the importance of aggressive treatment even in the cases with smaller size and more superficial location.