Central chondrosarcoma may present as osteolysis with vague borders, with or without interruption of cortical bone. Areas of x-ray opacity may be present within the tumor due to the tendency of the cartilage to calcify and ossify, and calcification often occurs around cartilage lobules without certain structure. It is characterized by irregular foggy granules, nodules or rings that are impervious to X-rays. Central chondrosarcoma is a chondrosarcoma of intraosseous origin, ranking 4th among primary malignant bone tumors, after plasmacytoma, osteosarcoma and Ewing’s sarcoma. There are distinct sites of predilection, in order of predilection, for the femur (especially proximal), pelvis, proximal humerus, scapula, and proximal tibia. What are the examination methods? 1.Bone imaging Bone imaging can diagnose bone tumor and bone metastasis 3~6 months earlier than X-ray examination, but it should be noted that this method is highly sensitive and low specificity. 2.CT examination of bone, joint and soft tissue CT examination of bone, joint and soft tissue is a method to examine bone, joint and soft tissue by CT. 3.Bone and joint MRI examination Bone and joint MRI examination is the use of MRI to scan the bone and joint, which is used to observe the condition of the bone and confirm the diagnosis of related diseases. It is suitable for patients with bone and joint diseases. 4.General radiography X-rays are mainly used to detect lesions in the bones, but they are also quite useful for detecting lesions in the soft tissues. Common examples are chest X-rays, which are used to diagnose lung diseases such as pneumonia, lung cancer or emphysema, and abdominal X-rays, which are used to detect intestinal obstruction, freeair (due to visceral perforation) and freefluid (free fluid). The use of X-rays for diagnosis is controversial in some cases, such as stones (which have little to no blocking effect on X-rays) or kidney stones (which are generally, but not always, visible).