From Pelvic Bone to Pleura: A Rare Metastatic Pathway in Osteosarcoma

A BSTRACT Osteosarcoma stands out as the predominant primary malignant bone tumor originating from primitive mesenchymal bone-forming cells. Its usual onset occurs in individuals aged 10–20 years, with occurrences beyond 40 years being rare, particularly in the absence of conditions such as Paget’s disease or osteogenesis imperfecta. Where lungs are the most common site for metastasis, the involvement of the pleura presents as an unusual aspect, given that pleural effusion and calcified thickening are not typical manifestations of osteosarcoma. This case involves a 61-year-old male who presented with osteosarcoma localized in the right pelvic bone, accompanied by concurrent right pleural effusion and calcified pleural thickening.