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)