Mandibular osteosarcoma is a rare malignancy that is clinically and pathologically difficult to differentiate from chondrosarcoma. We present a case of a 63-year-old man who had a huge progressive maxillofacial tumor with an incisional pathology of
chondrosarcoma. The imaging studies performed included X-ray, computed tomography, and magnetic resonance imaging. After radical surgery and free flap reconstruction, surgical pathology revealed chondroblastic osteosarcoma, and concurrent adjuvant chemoradiotherapy was scheduled. We compare osteosarcoma and chondrosarcoma in terms of clinical presentation, imaging, pathology, and treatment modality. The incidence of biopsy sampling error is 17 to 25%. Immunohistochemistry staining of galectin-1 and ezrin is helpful to distinguish osteosarcoma from chondrosarcoma.The appropriate adjuvant therapies are different between chondrobalstic osteosarcoma and chondrosarcoma, so we suggest that the final diagnosis and choice of a proper adjuvant therapy require comprehensive surgical pathology. (J Taiwan Otolaryngol Head Neck Surg 2020; 55:230-235)
