Extraskeletal masses are chondrosarcomas. Central chondrosarcoma is a chondrosarcoma that originates from within the bone. The main symptom is deep pain that is not intense and non-persistent. In the progressive stage of the tumor, large spherical extraosseous masses may form. There are distinct sites of predilection, in order of predilection, for the femur (especially proximal), pelvis, proximal humerus, scapula, and proximal tibia. The other bones of the trunk, the radius, the ulna, the foot, and the hand are the less frequent sites of softness (chondromas are common in the hand and less common in the trunk bones). The diagnosis of extraosseous masses is based on: 1. Primary chondrosarcoma is mostly seen in adolescents and occurs in the long bones of the extremities and the bones of the trunk. 2. Severe local pain, rapid mass growth, pressure pain and joint dysfunction. Secondary chondrosarcoma is mostly secondary to the original benign bone tumor and has a long course. Once malignant, the tumor grows rapidly and the symptoms are heavy. 4.The diagnosis can be confirmed by the characteristics of X-ray and pathological examination. (1) Imaging: Intramedullary: dotted and curved calcification points, scallop-like lace, cortical thickening. (2) Cortical: with or without periosteal reaction Soft tissue masses are evident. 5.Differential diagnosis: Chondrosarcoma should be diagnosed differently from endogenous chondrosarcoma, chondroblastoma, soft mucous fibers, bone infarction and other diseases.