It occurs in the lower end of the femur and the upper end of the tibia, accounting for about three-fourths of all osteosarcomas, and other places such as the humerus, the upper end of the femur, the fibula, the spine, and the ilium can also occur. Most of them are osteolytic and a few of them are osteogenic. Age of onset: it can occur at any age, but most of them are between 10 and 25 years old, and males are more common. The tumor is mostly at the end of the bone, and occasionally occurs in the diaphysis or epiphysis.
Osteosarcoma contains different components of cartilage, fibrous tissue and osteogenic tissue. The subperiosteal bone cortex and the medullary cavity can be infiltrated and spread. Early tumor main part in the subperiosteum, fusion in the bone cortex, osteolytic tumor tissue, less cartilage components, faster bone destruction, rich circulation, bone necrosis area can form parcels, tumor to the adjacent soft tissues proliferation, can occur pathological fracture, a small number of tumors bone hard. Generally, osteosarcoma does not invade the joints, occasionally destroys the cortex or involves the joints after pathological fracture.
Due to tumor development and periosteal reaction, there is often periosteal elevation to form a triangle commonly known as Codman's triangle, and there is a perpendicular sunshine-like radiating bone needle with the diaphysis.
Microscopically, there are many tumor cells, cells and nuclei of different sizes and shapes, including small multinucleated giant cells, spindle cells, immature chondrocytes, and malignant osteoblasts, with large nuclei and deep staining.
Almost all metastases are to the lungs via the bloodstream, and a few to the brain, viscera, kidneys, and lymph nodes via the lymphatics.
I. Clinical manifestations and diagnosis
Pain is an early symptom, which can occur before the appearance of the tumor, at first it is intermittent pain, and then it turns into persistent severe pain, especially at night. The pain of large malignant tumors occurs earlier and is more intense, and there is often a history of local trauma. The tumor at the bone end near the joints is large and of variable hardness, with pressure pain, high local temperature, venous dilatation, sometimes palpable pulsation, and may have pathological fractures. General health gradually declines to failure, and most patients have pulmonary metastases within a year.
X-ray manifestations: bone densification is variable. There is irregular destruction, the surface is vague, the boundary is unclear, the lesion mostly started in the epiphysis, due to tumor growth and periosteal reaction high up to form Calderman's triangle, there is a perpendicular direction with the diaphysis of the radial bone needle.
In addition to bone destruction and periosteal hyperplasia, daylight radial shadows can be seen
Clinically, adolescents should be carefully examined for pain and swelling at the end of the bone near the knee joint, and most of the cases can be diagnosed according to the history, signs and X-ray performance, and biopsy can be done if necessary.
Care should be taken to differentiate from the following lesions: osteomyositis, tuberculous osteitis of the metacarpals and metatarsals (osteosarcoma rarely occurs here), chronic osteomyelitis, bone cysts and giant cell tumors.
Treatment
After the diagnosis is clear, amputation or arthrodesis should be performed as early as possible, and chemotherapy and radiotherapy before and after surgery may improve the efficacy of the treatment, while chemotherapy or radiotherapy alone has little effect.