Osteosarcoma, also known as osteogenic sarcoma, is a malignant bone tumor that occurs mostly in adolescents or children under the age of 20. Osteosarcoma develops from a mesenchymal cell lineage, and the tumor grows rapidly due to the formation of tumor bone like tissue and bone tissue directly or indirectly through the cartilage stage. Osteosarcoma is the most common pediatric bone malignancy, accounting for approximately 5% of pediatric tumors. The prominent symptom of osteosarcoma is the pain at the tumor site, which is caused by the leaching and dissolution of bone cortex by tumor tissue. Osteosarcoma is the most common type of bone malignant tumor, which develops from mesenchymal cell lineage. The rapid growth of tumor is due to the formation of tumor bone like tissue and bone tissue directly or indirectly through cartilage stage. Weight-bearing bone of the lower extremities is subject to cell mutations by external factors (e.g., viruses) that may be associated with osteosarcoma formation. While the typical osteosarcoma originates from within the bone, another completely different type is the osteosarcoma juxtaposed to the bone cortex, which originates from the outer membrane of the bone and nearby connective tissue. The latter is less common and has a slightly better prognosis. The prominent symptom of osteosarcoma is pain at the tumor site, which is caused by the tumor tissue infiltrating and dissolving the bone cortex. (1) Pain Pain of different degrees at the tumor site is a very common and obvious symptom of osteosarcoma, which is caused by the swelling tumor tissue destroying bone cortex and stimulating periosteal nerve endings. The pain may develop from intermittent in the early stage to persistent after several weeks, and the degree of pain may be enhanced. Pain in the lower extremities may appear as pain-avoidance claudication. (2) Masses As the disease progresses, local swelling may appear, and a mass may be palpated in the painful area of the limb with obvious pressure pain. In case of rapid growth of the mass, the mass can be detected from the appearance. Increased skin temperature and superficial veins are revealed on the surface of the mass, and there may be varying degrees of pressure pain on the surface of the mass and nearby soft tissues. The hardness of the mass varies depending on the degree of ossification. The enlargement of the mass causes limitation of joint movement and muscle atrophy. (3) Claudication Pain-avoidance claudication caused by limb pain, which worsens with the progress of the disease, and the limitation of joint movement and muscle atrophy may occur in those with prolonged disease. (4) Systemic condition When the diagnosis is clear, the systemic condition is generally poor, manifested as fever, discomfort, weight loss, anemia and even failure. In some cases, the tumor grows rapidly and pulmonary metastasis occurs at an early stage, resulting in deterioration of general condition. The pathological fracture of the tumor site makes the symptoms more obvious. Diagnosis In cases of osteogenic osteosarcoma, an increase of bone-derived alkaline phosphatase in the blood can be detected at an early stage, which is related to the osteogenic effect of the tumor. Pathological diagnosis is the basis for treatment. When the diagnosis of osteosarcoma is considered, it is important to perform biopsy and get confirmation of pathological examination as soon as possible to clarify the diagnosis and treatment. (1) X-ray radiographs The X-ray of typical osteosarcoma shows bone tissue characterized by both new bone production and bone destruction. The tumor is located in the epiphysis of long tubular bones with indistinct margins, destruction of bone trabeculae, and increased density of tumor tissue. After penetrating the bone cortex, the tumor lifts up the periosteum, producing the characteristic X-ray sign of the disease – the Codman-sleeve triangle (Codman’s triangle). This phenomenon is seen in some patients with osteomyelitis and Ewing’s sarcoma, and is very typical in osteosarcoma. In advanced stages, shadows of tumor infiltration into soft tissues may be seen, and pathological fractures may be seen in some cases. (2) CT scan and MRI examination CT scan and MRI examination are effective means to determine the nature and extent of bone tumor and the presence of surrounding soft tissue infiltration, and can detect metastatic lesions in lung and other organs at an early stage, which is a routine item in the clinical examination of osteosarcoma. (3) Nuclear bone scan Nuclear bone scan is a common method for early detection and late identification of metastatic lesions. Osteosarcoma is still a disease with high mortality rate in children and adolescents, but early detection and timely treatment have largely improved the survival rate of the disease. After the diagnosis of osteosarcoma is confirmed by pathology, the preliminary chemical or radiotherapy is started, and the removal of tumor tissue is an important step in the treatment of osteosarcoma. With the improvement of surgical oncology techniques and the development of built-in object research, limb preservation therapy has shown better treatment prospects. Consolidation chemotherapy or radiotherapy after tumor tissue removal is very important to control tumor metastasis and improve survival rate. Radical surgery should be performed to treat osteosarcoma. Those who have the condition can do extensive local excision while preserving the limb. In addition, biopsy should be done before amputation. Immunotherapy is intravenous lymphocyte input or interferon and transfer factor, but the efficacy is not sure. 5. Prognosis The closer the tumor site is to the trunk, the higher the death rate. As for the relationship between the type of tumor and the richness of blood vessels and the prognosis, it is difficult to judge, and attention should be paid to the immune response of patients. Some advanced tumors do amputation, some of them can survive for a long time without recurrence after radiation therapy and lung metastasis can be dissipated. , which may be related to the immune response. The key factors affecting prognosis are early diagnosis, complete resection of tumor, chemotherapy and radiotherapy before and after surgery. It is also related to the tissue type and size of the tumor cells, changes in the increase of serum alkaline phosphatase before and after surgery, and whether local lymph nodes are involved.