Bone tumors can be divided into two types: primary and secondary, depending on their origin. Primary tumors start in the bone system itself, and there are many benign tumors with long disease duration and good prognosis; there are few malignant tumors with short disease duration and poor prognosis, and the mortality rate can reach 80-90%. Cancer cells from other tissues or organs can metastasize to bone tissue through blood circulation or lymphatic system (or occasionally invade bone due to direct infiltration) and gradually develop into metastases in bone tissue with poor prognosis. Bone is composed of various tissues and can be divided into two categories: bone essence and bone appendages. The bone essence has endosteal, eposteal, bone and cartilage tissues. These tissues are referred to as bone tissues. The bone appendages include blood vessels, nerves, fat, hematopoietic tissues, and reticuloendothelial system tissues, which are referred to as bone appendage tissues. Both bone tissue and bone accessory tissue can produce tumors, and the clinical development, treatment and prognosis of each tumor are different. Therefore, it is necessary to classify primary bone tumors into two categories: bone histoma and bone accessory tissue tumors. Benign bone tumors include: osteoma, osteochondroma, chondrosarcoma, chondroblastoma, osteoid osteoma and giant cell tumor of bone. Malignant bone tumors (also known as osteogenic sarcoma) include: osteosarcoma, chondrosarcoma, and osteofibrosarcoma. Benign bone appendage tumors include: bone hemangioma, neurofibrillary flow. Malignant bone tumors include undifferentiated reticulocytoma, reticulocytic sarcoma of bone and myeloma. Diagnosis: Some of the bone tumors are easy to diagnose, and the preliminary diagnosis can be made based on clinical examination alone, such as superficial osteoma or osteochondroma, etc. Some of them have characteristics on x-ray, and the preliminary impression can be made based on the typical x-ray, such as sclerosing osteosarcoma and chondrosarcoma, etc. Some of them need to be combined with clinical, x-ray and pathology to make the correct diagnosis. Therefore, clinical, x-ray and pathology are considered as three important steps in the diagnosis of bone tumor, and sometimes one of them is indispensable. Especially before considering the surgery of limb amputation, the diagnosis is usually confirmed by the above three aspects of examination before deciding. In terms of differential diagnosis, this disease should first be differentiated from inflammatory disease. The main points of differentiation are the following four aspects: (a) Systemic reaction: acute inflammation patients often have elevated body temperature and increased white blood cell count, while benign bone tumor patients have normal body temperature and normal blood picture. Some patients with malignant bone tumors such as undifferentiated reticulocytic sarcoma or rapidly growing malignant tumors also show elevated body temperature and increased white blood cell count. The blood sedimentation of patients with acute and chronic inflammation and bone tuberculosis is mostly increased, that of patients with benign bone tumors is mostly normal, and that of patients with malignant bone tumors is often increased. (2) Development process: Inflammation gradually subsides after developing to a certain extent or after anti-inflammatory treatment, some benign bone tumors can stop developing after developing to a certain extent, while malignant bone tumors continue to develop and destroy, and those who stop or disappear by themselves are extremely rare. (3) Local palpation: Inflammation often produces abscesses, which are generally soft and have obvious fluctuations. Bone tumors are generally harder or tougher and have a solid feeling when touched, with clear borders. However, certain malignant tumors that are rich in blood vessels or have bleeding may also have fluctuating sensation. (4) Puncture: abscess puncture can mostly aspirate pus, and pus culture or smear staining can sometimes detect septic bacteria. Tumor puncture can only aspirate blood, and sometimes tumor tissue fragments can be aspirated by thick needle puncture. Benign bone tumor should also be distinguished from malignant bone tumor, because the prognosis and treatment methods of the two are different. The main points of differentiation are as follows: (a) Systemic reaction: In addition to the difference in body temperature, blood picture and blood sedimentation between benign bone tumor and malignant bone tumor, the former has good general condition and less pain, while the latter has wasting, anemia, pain and obvious cachexia. (2) Development speed: benign bone tumors generally develop slowly, and some of them stop developing at a certain age. However, malignant tumors develop rapidly and even form huge masses with angry surface veins. (3) Metastasis or not: benign bone tumors generally do not metastasize, while primary malignant bone tumors are more likely to metastasize to internal organs and other bones. （There is usually no periosteal reaction, and if there is, the periosteal new bone is also more regular and neat. In malignant bone tumors, the boundary is not clear, and there is no clear demarcation between normal bone and periosteal reaction, even forming daylight radiolucency.