1.What is bone tumor? Tumors that occur in bone or originate from various tissue components in bone, such as bone, cartilage, fibrous tissue, adipose tissue, hematopoietic tissue, nerve tissue and undifferentiated reticular endothelial structure, are collectively called bone tumors. Bone tumors can be classified as primary or secondary, depending on their origin. Primary tumors start from the bone system itself and are classified as benign or malignant. Benign bone tumors have a low recurrence rate, are not easily metastasized and have a good prognosis; on the contrary, malignant bone tumors have a high recurrence rate, are easily metastasized and have a poor prognosis. Tumor cells from other tissues or organs in the body may metastasize to bone tissue through blood circulation or lymphatic system (occasionally, they may also invade bone by direct infiltration), forming metastases, which may be single or multiple, with poor prognosis. In addition, some lesions are not real tumors, but their clinical, X-ray or pathological manifestations are similar to bone tumors, which are called tumor-like lesions, such as isolated bone cyst, bone fiber heteroplasia, etc. 2.What is the difference between bone tumor and “bone cancer”? All tumors that occur in bone or originate from various tissue components in bone are collectively called bone tumors, so bone tumors are the largest category of this type of tumors. Among malignant tumors, those from epithelial tissues are called “cancer”, such as lung cancer, liver cancer, etc.; those from mesenchymal tissues are called “sarcoma”, such as osteosarcoma, fibrosarcoma, etc. Since bone tissue is derived from mesenchymal tissue, malignant tumors occurring in bone tissue are called “sarcoma”, and the term “bone cancer” is wrong. 3.How are bone tumors classified? Classification: benign and malignant. Osteogenic tumors: osteoma, osteoid osteoma, benign osteoblastoma, osteosarcoma, paracortical osteosarcoma, malignant osteoblastoma; chondrogenic tumors: osteochondroma, chondrosarcoma, chondroblastoma, mucinous fibroma of cartilage, chondrosarcoma; giant cell tumor of bone: giant cell tumor of bone, malignant giant cell tumor of bone; tumors of bone marrow origin: Ewing sarcoma, myeloma, lymphoma; connective tissue tumors. Ligamentous fibroma, non-ossifying fibroma, fibrosarcoma; vascular tissue tumors: hemangioma, lymphangioleioma, hemangioblastoma, hemangioendothelioma, hemangioepithelioma; adipose tissue tumors: lipoma, liposarcoma; nerve tissue tumors: nerve sheath tumor, neurofibroma, malignant nerve sheath tumor; tumors of chordal origin: chordoma; tumor-like lesions: isolated bone cyst, fibrous dysplasia of bone, eosinophilic Acid granuloma. 4.How are bone tumors staged? In 1980, Enneking proposed a surgical staging system for tumors of musculoskeletal system, namely G-T-M surgical staging system: G indicates pathological grading, T indicates the relationship between tumor and anatomical interval, and M indicates lymph node invasion and distant metastasis. Benign tumor staging: grade 1 quiescent tumor with intact capsule; grade 2 active growth, still located in the capsule; grade 3 invasive, can penetrate the cortex or septum. Malignant tumors are divided into IA, IB, IIA, IIB, IIIA and IIIB stages according to G, T and M. Their malignant degree gradually increases and treatment measures also change. The surgical staging system of bone tumor provides a reasonable standard for the selection of the timing and scope of surgery, so that it has a common basis for selecting the corresponding surgical methods and comparing the treatment results, which makes the conclusion accurate and reasonable, and helps to judge the prognosis and provides the guiding principle for the adjuvant treatment. 5.What are the factors for the development of bone tumor? The factors of bone tumor development are very complicated, and there is no exact cause yet. The internal factors include quality theory, genetic theory, endocrine theory, etc. The external factors include chemical element substance and chronic stimulation theory by internal and external irradiation, viral infection theory, etc. Some multiple osteochondromas and fibrous proliferative disorders are related to family inheritance. The age of predilection for different bone tumors varies, with osteosarcoma occurring between 10-30 years old, chondroblastoma occurring between 10-20 years old, and giant cell tumor of bone occurring between 20-40 years old. Benign tumors of bone can become malignant: for example, osteochondroma multiforme can malign into chondrosarcoma; fibrodysplasia can malign into fibrosarcoma. Some patients with bone tumors often recall the history of trauma, such as sprains and bruises, but in fact, such trauma does not cause bone quality changes, and osteosarcoma in fracture site is extremely rare. In conclusion, the occurrence and development of bone tumor, like other tumors, is still a mystery, which we have to solve. 6.What is pathological fracture? Pathological fracture is a fracture based on some diseases. The most common cause is a primary or metastatic tumor of bone. Other factors that may lead to pathological fractures include osteoporosis, hyperparathyroidism, and infection. Unlike a purely traumatic fracture, in a pathological fracture, the bone is pre-eaten, damaged, and hollowed out by some disease, and can then spontaneously fracture with a slight external force, or even without an external force due only to its own gravity. Therefore, when a fracture occurs, if the external force causing the fracture is very mild, if there is pain in the area before the fracture, or if the fracture has occurred in the same area or in other areas in the past, then you should be alert to the possibility of a pathological fracture. Pathological fractures cannot simply be treated for fracture, but also for the cause of the disease.