Abstract
Primary osteosarcomas are derived from primitive bone-forming mesenchymal stem cells and most often originate in the metaphysis of the long bones of children and adolescents, but it occurs very rare in adults. Approximately 10% of osteosarcomas are located in the flat bones, pelvis being the main site. Involvement of flat bones like rib may be seen as a metastatic process or secondary to chemotherapy, but a primary osteosarcoma rib is extremely rare. Osteosarcoma originating from such rare sites poses numerous diagnostic and therapeutic challenges, and we report one such case in a 24-year-old male patient. Our case highlights the fact that osteosarcoma of the rib, although rare, should be considered in the differential diagnosis of primary malignant neoplasms of the rib even in the adult population. Further, early prompt diagnosis and aggressive multimodality management are cornerstones of management and will help improve the survival outcomes.