What are the diagnostic tools for osteosarcoma

Now more and more children or teenagers are unfortunately suffering from osteosarcoma, which poses a great threat to the healthy growth of children or teenagers. For this reason, a lot of medical research has been done on osteosarcoma, a malignant tumor disease. In order to more accurately diagnose the patient's condition and carry out scientific symptomatic treatment, I will introduce to you what are the commonly used osteosarcoma diagnostic tools?

Osteosarcoma is the most common primary bone malignancy in children and adolescents. The first symptoms are usually pain and swelling. It is often intermittent at first, but quickly turns into persistent severe pain, especially at night. Local tenderness is obvious during palpation, and the surface skin becomes hot and red, accompanied by venous distension. The most common way of metastasis is hematogenous metastasis to the lungs. The current treatment plan for osteosarcoma is preoperative chemotherapy-surgery-postoperative chemotherapy. Before treatment, we need to use the following diagnostic tools to confirm the diagnosis.

1. X-ray film

X-ray films are the initial screening method for lesions. The main manifestations are irregular bone destruction and bone hyperplasia in the bone marrow cavity, bone cortical destruction, different forms of periosteal hyperplasia and re-destruction of periosteal new bone, soft tissue masses and tumor bone formation therein. The diagnosis is mainly based on tumor bone, which generally appears as cloud-like, needle-like and plaque-like dense shadows. These tumor bones are immature bone tissues, which are directly formed by tumors and have no normal trabeculae. Most osteosarcomas can be qualitatively diagnosed by plain films, but the limitation is that the display of tiny bone destruction and soft tissue masses is unsatisfactory. According to the amount and stage of the above X-ray manifestations, osteosarcoma can be roughly divided into osteoblastic, osteolytic and mixed types, with mixed types being more common. Osteogenic osteosarcoma is mainly formed by tumor bone, which is a uniform ossification shadow, patchy, and wide in range. When it is obvious, it can appear as a large dense shadow called ivory change. Periosteal hyperplasia is more obvious. Osteolytic osteosarcoma is mainly characterized by bone destruction, with little or no bone formation. The destruction is mostly biased to one side, presenting irregular patches or large pieces of osteolytic bone destruction with unclear boundaries. Periosteal hyperplasia is easily destroyed by the tumor, but remains at the edge, forming a periosteal triangle. Extensive osteolytic destruction is prone to cause pathological fractures. The degree of osteogenesis and osteolysis in mixed osteosarcoma is roughly the same. More tumor bones can be seen in the osteolytic destruction area and soft tissue mass, with uneven density and different shapes.

2. CT examination

CT examination is mainly used to detect suspicious bone destruction and tumor bone in plain film examination, and plays an important supplementary role to plain film. The bone destruction of osteosarcoma is mainly osteolytic, and CT shows patchy defects in cancellous bone, erosion of the inner surface of the bone cortex, or worm-eaten, patchy destruction of the entire layer of the bone cortex, or even large defects. Bone hyperplasia is manifested as irregular patchy high-density shadows in cancellous bone and thickening of the bone cortex. Soft tissue masses often tend to grow on one side of the diseased bone or around the diseased bone. Their edges are mostly blurred, and they are not clearly demarcated from the surrounding normal muscles, nerves and blood vessels. Necrotic cystic areas of varying sizes are common in them. CT is more sensitive than plain film in detecting tumor bones. Tumor bones are distributed in bone destruction areas and soft tissue masses. The morphology is similar to that seen in plain films, but the density difference is large. CT can well show the relationship between the tumor and the adjacent structures, and can also better show the spread of the tumor in the medullary cavity, which is manifested as low-density fat-containing bone marrow replaced by tumors with soft tissue density. Enhanced scanning can show obvious enhancement of the solid part of the tumor (non-ossified part), making it clearer to distinguish the tumor from the surrounding tissues.

3. MRI

MRI is an essential examination method for staging osteosarcoma, and is often used as the main means to evaluate the efficacy of neoadjuvant chemotherapy. When the bone marrow is infiltrated by tumor, even if it is very slight, it can show abnormal signals. MRI can clearly show the relationship between the tumor and the surrounding normal structures such as muscles, blood vessels, nerves, etc., as well as the spread of the tumor in the medullary cavity and to the epiphysis and joint cavity. It is more sensitive than plain film and CT in showing cortical tumor infiltration. When the cortical tumor infiltrates and the morphology remains, plain film and CT may be negative, but MRI can detect abnormalities. However, MRI's ability to display small, thin ossification or calcification is far inferior to CT. It is difficult to distinguish it from other malignant tumors based on signal changes alone, which may make the qualitative diagnosis of osteosarcoma difficult.

Osteosarcoma has a clear age of onset and site of invasion, and its imaging manifestations are also characteristic. X-ray films showing typical osteosarcoma can confirm the diagnosis, but it cannot determine the extent of bone marrow invasion, let alone detect skipping sub-foci in the bone marrow, and it also has great limitations in accurately determining the extent of soft tissue invasion. Therefore, it is advisable to further perform MRI examinations on the basis of X-ray films to provide more direct and accurate information for treatment. The final diagnosis of osteosarcoma must be combined with pathology, imaging, and clinical comprehensive diagnosis, and none of the three can be missing.