Orthonotes
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Benign: slow, well circumscribed, no metastasis. Malignant: rapid, infiltrative, metastasis. Histology: benign differentiated; malignant atypia, mitoses, necrosis. Radiology: benign geographic margins; malignant permeative with periosteal reactions.
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Tumour biology in orthopaedics focuses on the behavior, growth pattern and biological characteristics of bone and soft tissue tumours. Understanding the biological differences between benign and malignant tumours is essential for diagnosis, treatment planning and prognosis.
Bone tumours arise from abnormal proliferation of cells within bone or surrounding soft tissues. These tumours may be benign with slow growth and limited local invasion, or malignant with aggressive growth, local destruction and potential for metastasis.
Orthopaedic oncologists evaluate tumour behavior through clinical presentation, imaging findings, histopathology and staging systems. Accurate differentiation between benign and malignant tumours is crucial because management strategies differ significantly.
Tumours develop when normal cellular regulatory mechanisms controlling proliferation and apoptosis become disrupted. Genetic mutations allow abnormal cells to multiply uncontrollably and evade normal growth regulation.
Several biological factors influence tumour behavior including cellular differentiation, vascular supply, growth rate and metastatic potential.
| Feature | Benign Tumours | Malignant Tumours |
|---|---|---|
| Growth rate | Slow growth | Rapid growth |
| Margins | Well defined | Poorly defined |
| Local invasion | Do not invade surrounding tissue | Invade surrounding structures |
| Metastasis | Absent | Common |
| Recurrence | Rare after excision | Frequent |
Bone tumours demonstrate different growth patterns depending on their biological behavior. Radiographic features often reflect the aggressiveness of the tumour.
| Growth Pattern | Characteristics | Examples |
|---|---|---|
| Latent | Slow growing and asymptomatic | Non ossifying fibroma |
| Active | Expanding lesion with cortical thinning | Giant cell tumour |
| Aggressive | Rapid growth with cortical destruction | Osteosarcoma |
Malignant tumours possess the ability to invade surrounding tissues and spread to distant organs. Tumour spread occurs through several mechanisms.
Bone sarcomas most commonly metastasize to the lungs through the bloodstream.
Angiogenesis refers to the formation of new blood vessels that supply nutrients and oxygen to the tumour. Malignant tumours stimulate angiogenesis through growth factors such as vascular endothelial growth factor.
The development of a vascular network allows the tumour to grow rapidly and increases the risk of metastasis.
The human body mounts an immune response against tumour cells. However malignant tumours often develop mechanisms to evade immune detection.
Understanding tumour biology assists clinicians in selecting appropriate treatment strategies. Benign tumours may require observation or simple surgical excision, whereas malignant tumours often require multimodal treatment including surgery, chemotherapy and radiotherapy.
Knowledge of tumour biology also guides imaging interpretation, biopsy planning and surgical margins during tumour resection.
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