Osteosarcoma clinical features and treatment principles
Definition: malignant osteogenic tumor, histologically characterized by direct osteogenesis or production of bone matrix by tumor cells
Classification: Central and superficial types, with common central osteosarcoma being the most common.
Imaging features.
X-rays mostly show long tubular bone epiphysis with subcortical, ill-defined bone destruction on one side. Peripheral trabeculae are blurred and bone density is increased, causing periosteal reactive osteogenesis, which is seen as Codman’s triangle. In unclosed epiphyses, the tumor may terminate at the epiphyseal plate or may bypass or cross the epiphyseal plate into the epiphysis.
Clinical manifestations.
1. It is common in young people aged 10-20 years old, and occurs in middle age mostly secondary to Paget’s disease, bone giant and bone fiber.
2, the main symptoms are pain, increased at night, gradually aggravated, surface skin congestion and fever, venous anger, early prone to lung metastases.
3.Bone destruction is prone to pathological fracture.
4, ALP is increased in most cases, after effective chemotherapy or surgical removal of the primary lesion, ALP can be reduced to normal, if it is elevated again, it indicates the possibility of recurrence or metastasis.
Pathological examination.
Naked eye observation of the dissection is mostly white, interspersed with fish-like tissue, hemorrhage, necrosis, tumor bone and remnant bone. Microscopically, highly malignant histological manifestations of spindle cells are seen, surrounded by irregularly shaped, immature bone or bone stroma that does not follow the direction of stress.
Staging.
Ennecking staging consists of GTM.
G is the pathological grading: G1 low malignancy, G2 high malignancy.
T is the anatomical localization where the tumor is located: T0 is benign tumor confined to the bone, T1 is intra-interstitial, and T2 is extra-interstitial.
M refers to metastasis: M0 has no metastasis, M1 has metastasis.
Different stages are formed according to different combinations of GTM.
Stage ⅠA: G1 T1 M0
Stage ⅠB: G1 T2 M0
Stage IIA: G2 T1 M0
Stage IIB: G2 T2 M0
Stage IIIA: G1-2T1M1
Stage IIIB: G1-2T2M1
Differential diagnosis.
Need to be differentiated from chronic septic osteomyelitis, Ewing’s sarcoma, metastatic bone tumor, and osteoarticular tuberculosis.
1. Chronic septic osteomyelitis usually has no acute onset, and the lesion is relatively limited without the tendency to spread widely to the whole bone. Not only can there be periosteal hyperplasia in the area, but also a varying number of tumor bones are common. The soft tissues may be invaded through the bone cortex to form soft tissue masses. It can be differentiated from the latter. Osteosarcoma has a clear age of predilection and site of invasion, and the imaging is also characteristic. The diagnosis of typical osteosarcoma can be confirmed by radiography, but it cannot determine the extent of bone marrow invasion, let alone detect jumping subfoci within the bone marrow, and has a greater limit to accurately determine the extent of soft tissue invasion. Therefore, further MRI examination is recommended on the basis of X-ray plain film to provide more direct and accurate information for clinical treatment.
2.Ewing’s sarcoma: It is characterized by intra-medullary speckled and rat-bite osteolytic destruction, with a long range and onion skin-like periosteal reaction.
3.Metastatic tumor: It is less likely to invade the bones near the knee joint, but more likely to occur in the pelvis and spine, etc. The bone changes are mostly osteolytic, mostly without periosteal reaction and soft tissue masses.
4. Bone and joint tuberculosis: It is a chronic disease, and the pain is not severe. Local swelling of osteoarticular tuberculosis is large, and most cases have joint surface destruction. Osteosarcoma rarely invades the interior of the joint.
It is sometimes difficult to distinguish osteosarcoma from other malignant bone tumors, and histopathological examination is required to make the final diagnosis.
Treatment principles.
1. Chemotherapy.
The four most commonly used drugs: methotrexate, cisplatin, adriamycin, isocyclophosphamide
2, surgery.
①: limb-preserving surgery.
gradually become mainstream, the best indication for stage IIA, IIB is a relative indication. Pre-operative standardized chemotherapy is required for 6~8 weeks, and the cutting edge should reach radical resection or extensive resectability. Preoperative MRI and angiography are preferable to understand the exact extent of the tumor and the relationship of large blood vessels. Bone defects are mostly replaced by artificial joints, and the chemotherapy regimen is then adjusted to treat the tumor for 4~6 months after surgery according to the tumor necrosis rate.
②: Amputation surgery
When limb preservation is inappropriate or unconditional, amputation should be decisively performed, without chemotherapy before surgery, but chemotherapy is necessary after surgery.