Bone tumour Flashcards
What are osteoblasts?
- Bone forming cells
- Make the matrix
- type 1 collagen, ground substance, calcium hydroxyapatite
What are osteocytes?
Mature bone cells
What are osteoclasts?
Bone resorbing cells
Where is mature lamellar bone?
Normal mature bone in the skeleton, may be compact or cancellous
Where is immature woven bone?
- Foetus
- Fracture
- bone tumour
What is the most common primary bone tumour?
Myeloma
What are the most common metastatic carcinomas spreading to bone?
- Bronchus
- Breast
- Prostate
- kidney
- Thyroid (follicular)
What tumours in childhood can affect bone?
Neuroblastoma, rhabdomyosarcoma
Which bones are more likely to be affected by cancer?
Those with a good blood supply: femur, femoral head, humerus, pelvis
What are the effects of metastases to bone?
- Often asymptomatic
- bone pain
- bone destruction
- pathological fracture in long bones
- spinal metastases> vertebral collapse, spinal cord compression, nerve root compression, back pain
- Hypercalcaemia (thirst, abdominal pain)
What is the mechanism of bone destruction?
- Osteoclasts, not tumour cells
- Osteoclasts are stimulated by cytokines from tumour cells
- inhibited by bisphosphonates
Explain sclerotic metastases
- Prostatic carcinoma, breast carcinoma
- Sclerotic (bright) on X ray
- Reactive new bone formation induced by the tumour cells
Explain solitary bone metastases
- Typically renal and thyroid carcinoma
* Surgical removal is often valuable
What is myeloma
- Malignant primary bone tumour
- Monoclonal proliferation of plasma cells in the bone marrow
- Solitary (plasmacytoma) or multiple myeloma if many
What are the clinical effects of myeloma?
•Lytic bone lesions - bone pain and fracture
•Marrow replacement: anaemia, infection, bleeding
•immunoglobulin excess:
- serum electrophoresis: monoclonal band
- urine: immunoglobulin light chain (bence jones)
What are the effects of marrow replacement by tumour?
- Pancytopenia
- Anaemia
- Leucopenia - increased infections
- Thrombocytopenia: haemorrhage
What are the benign primary bone tumours?
- Osteoid osteoma
- Chrondroma
- Osteocartilagenous exostosis (combination of bone and cartilage)
What are the malignant primary bone tumours?
- Osteosarcoma
- Chrondrosarcoma
- Ewing’s tumour
- Myeloma
What is osteoid osteoma?
- Small, benign osteoblastic proliferation
* Pain worse at night, relieved by aspirin
What is osteosarcoma?
Malignant tumour whose cells form osteoid or bone
What is the peak age of osteosarcoma?
10-25, second peak in adulthood
What is the typical site of osteosarcoma
- Metaphysis of long bones
* 50% around the knee
How does osteosarcoma present?
- bone pain
- swelling
- Pathological fracture
- Often delayed presentation
What is the natural history of osteosarcoma?
- Highly malignant
- Haematogenous spread
- Early lung metastases
- 5 year survival pre chemo 15-20%, modern survival 50-60%
Describe imaging in osteosarcoma
- Look for lytic destructive lesion
- Cortical destruction with soft tissue mass
- Codman trinangle: old cortex being lifted up by new cortex being produced in response to tumour
What is the treatment of osteosarcoma?
- neoadjuvant chemotherapy
- Followed by local excision, limb sparing
- Further chemotherapy
- May then have radiotherapy for local control
What are the cartilaginous tumours?
•Benign:
- enchondroma
- osteocartilaginous exostosis
•Malignant:
- chrondrosarcoma
What is osteocartilaginous exostosis?
- Benign outgrowth of cartilage with end-chondral ossification
- Probably derived from the growth plate
- Very common, usually adolescence
- Metaphysis of long bones
How is osteocartilaginous exostosis treated?
Surgical resection
What is enchondroma?
- Lobulated mass of cartilage within the medulla
- > 50% in hands, feet, long bones
- Often asymptomatic in long bones
- in hands - swelling and pathological fracture
- Low cellularity, often surrounded by plates of lamellar bone
What is chondrosarcoma?
- primary or from pre-existing enchrondroma or exostosis (secondary)
- Central, within the medullary canal or peripheral on bone surface
- predominantly middle aged and elderly, male>females
Where are the common sites of chrondrosarcoma?
- Axial skeleton
- Pelvis
- Ribs
- Shoulder girdle
- Proximal femur and humerus
How does chondrosarcoma present?
- Bone pain
- Swelling
- pathological fracture
- Neurological symptoms
What is the appearance of chrondrosarcoma on imaging?
- Popcorn calcifications
- lytic
- May get cortical destruction with soft tissue mass
What mutations are associated with chondrosarcoma?
IDH1 and IDH2
What is the peak age of Ewing sarcoma?
5-15 years
Where are the common sites of Ewing sarcoma?
- Long bone
* flat bones of limb girdles
Metastases of Ewings sarcoma
- Early metastases to lung, bone marrow and bone
* Micrometastases
What is the presentation of Ewing sarcoma?
- Pain
- Swelling
- Night sweats
- Weight loss
- Fever
What is the appearance of Ewing sarcoma on Xray?
- Moth eaten appearance
- lytic lesion
- Periosteal new bone formation - onion skinning
How is the diagnosis of Ewing sarcoma made?
Biopsy
What is the associated mutation with Ewing sarcoma?
•90% show translocation between chromosomes 11 and 22
What is the treatment of Ewing sarcoma?
- Neoadjuvant chemotherapy (doxorubicin, cyclophosphamide, vincristine)
- Surgery
- Further chemo
- May need radiotherapy
