I. As seen by the naked eye, in well-differentiated and collagenized specimens, the tissue of fibrosarcoma is dense, white, and quite hard. In poorly differentiated specimens, the tumor tissue is softer, liquefied, congested, and can range in color from white to pink to gray, with a substantial or distinctly medullary appearance, often with hemorrhagic, necrotic, or cystic areas, and sometimes with mucinous areas, because there are significantly more cells than fibers in the tumor and it is more vascular. Second, bone fibrosarcoma seen under the microscope is graded according to its malignancy and differentiation degree, this grading is not clear and subjective, but the grading is related to the prognosis and treatment. Grade I fibrosarcoma: It is distinguished from sclerofibrosarcoma. It is characterized by its more numerous tumor cells, more plump nuclei, slightly too dark staining, more pronounced pleomorphism, some mitotic images, and abundant collagen fibers. Grade II Fibrosarcoma: The tumor tissue is dense, homogeneous, and characterized by bundles and stream-like structures typically arranged in a herring-like pattern. Cells are abundant, relatively large, and spindle-shaped. The nuclei are plump, darkly colored, less pleomorphic, and mitotic images are common and may be irregular. Collagen fibers are relatively sparse or very sparse, and silversophilic reticular tissue is abundant and diffuse, encircling virtually all cells, and, at times, fibers form large bundles and glassy collagen surrounding the tumor cells, encapsulating them. Blood vessels are relatively abundant, with a continuous vascular wall. Sometimes the stroma absorbs fluid to produce a mucus-like appearance. Grade III-IV Fibrosarcoma: Collagen fibers are scarce, and the characteristic bundles and current-like structures arranged in a herring-like pattern lose their predominance in favor of cells. The cells are large and pleomorphic. The nuclei are hyperchromatic and heterogeneous, with occasional malformations or multiple nuclei. Mitotic images are numerous and irregular. Vessels may be cavitated with discontinuous vessel walls. At all levels of fibrosarcoma, there may be benign (reactive) infiltration of multinucleated giant cells and inflammatory cells, especially lymphocytes. Clinical manifestations Low incidence, at least 10 times lower than that of osteosarcoma. There is no significant gender difference, or only a slight predilection for males. It can occur at any age, with little difference in distribution between 15 and 60 years of age, and isolated cases occurring before puberty. It occurs in the following areas, in order of prevalence, distal femur, proximal tibia, proximal femur, proximal humerus, and pelvis; in about 50% of cases it occurs around the knee, 20% in the proximal bones of the limbs, 20% in the bones of the trunk, and rarely in the bones of the hands and feet. In the long bones, it is usually located to one end of the diaphysis or epiphysis; in adults, it often invades the epiphysis, and it is rare to find it purely localized to the diaphysis. Multiple fibrosarcomas are rare and are usually located in one or more bones of the same limb. Multiple fibrosarcomas located in both bone and soft tissue, or occurring sequentially, are also rare. The main symptoms are pain and swelling. In fibrosarcomas of low malignancy, the swelling is mild and late, sometimes absent, but when the fibrosarcoma is more aggressive, the swelling appears earlier. Pathologic fractures are common in fibrosarcoma. Laboratory and other tests i. X-rays are dominated by osteolytic lesions that are geomorphic and wormlike without any tumorigenic osteogenesis. Its osteolysis is extensive, with blurred borders, broken cortical bone, invasion into soft tissues, and little or no periosteal bone reaction. In some cases, fibrosarcoma can penetrate cancellous bone and cortical bone, producing “worm-like” images, with few osteolytic areas and fusion. Second, CT manifestation of fibrosarcoma in the medullary cavity of bone CT scanning manifested as local bone mild expansion, cortical thinning, reduced density in the focal area, and high-density punctate calcification can be seen within the lesion. If it occurs in the periosteum, it often manifests as a soft tissue mass with uneven density, and there are a few homogeneous high-density calcification points in it.CT enhancement scan shows that the density of the mass can be increased to different degrees. MRI shows low signal intensity on T1-weighted image, and high signal, low signal or mixed signal on T2-weighted image according to the different differentiation degree of the tumor. Diagnosis Diagnostic criteria: 1, prevalent age between 15-60 years old, mostly seen after middle age, no obvious gender difference. 2.Preferred site: it occurs in the metaphysis or bone end of long tubular bone, with the femur, tibia, humerus being the most common, and flat bone can also occur. 3.Slow onset, few symptoms, mainly localized swelling and mild pain. 4.Imaging examination shows osteolytic destruction, rarely osteosclerosis and periosteal reaction. Differential diagnosis: 1. Reticulocyte sarcoma of bone is sometimes clinically very similar to the two, and it is not easy to differentiate between them. However, reticulocytosarcoma of bone occurs in long bones, scapula and other places also occur longer, and the symptoms are lighter, the course of the disease is longer, and the X-ray manifestation is dominated by osteolytic destruction, and the range is extensive. B. Giant cell tumor of bone with severe osteoid destruction was presenting expanding osteolytic destruction at the end of bone. At this time, it is easy to be confused with osteofibrosarcoma and must be identified with the help of pathologic section. In histology, grade I fibrosarcoma may be difficult to distinguish from sclerofibrosarcoma, but in fibrosarcoma, the cell nuclei are more numerous, larger and plump, with mildly excessive staining and obvious pleomorphism, mitotic images, less collagenous components and less maturity. Treatment i. Wide excision is indicated for grade I fibrosarcoma. It may be indicated in cases of selective grade II-IV fibrosarcomas, where the site and degree of expansion of the tumor permits a fairly wide excision in these selective cases. Most cases of fibrosarcoma, especially grade III-IV fibrosarcoma, require amputation. Because the tumor is quite expanded in the bone at the time of surgery (lack of symptoms and late timing of surgery) and because of the high rate of postoperative residual limb recurrence, the site of amputation must be carefully determined, with reference to arteriography, bone scan, CT, and MRI, and the site of amputation must be well away from the site of the tumor. For example, when the fibrosarcoma is located in the femur, the amputation site must be very high, and sometimes hip disarticulation or ilioinguinal disarticulation is required. The amputation site of fibrosarcoma is often higher than that of osteosarcoma. Radiotherapy and chemotherapy are not sensitive to radiotherapy, and radiotherapy is only used as palliative treatment for those who cannot be operated. Preoperative chemotherapy has no significant effect and is not routinely used. Periodic combination chemotherapy is feasible after surgery, and the chemotherapy regimen is that of osteosarcoma, which can be tried in high-risk cases and patients of age.