RESUMO
Extraskeletal osteosarcoma (ESO) is a rare form of osteosarcoma that has no attachment to bone and can be found in the thigh, retroperitoneum, chest, breast, orbit, retropharyngeal space etc. Literature about ESO is still mainly case reports and case series with few reported cases in our environment. We therefore report this 52-year-old with swelling at the left shoulder which progressed over a 3-year period. Pre-operative evaluation (both clinical, radiological and histopathological) were in favor of soft tissue sarcoma. A wide local excision showed no bony attachment intra-operatively. Histology of the specimen confirmed ESO. Patient had adjuvant chemotherapy and was followed up for 14 months before this report with no sign of local recurrence or distant metastases.