Discuss the basic epidemiology, pathophysiology, presentation, investigation, management and prognosis of bony metastasis

Question 1

What are sunray spicules?

Answer 1

calcification within the tumour but outside the bone

Question 2

How are secondary bone tumours formed?

Answer 2

1. neovascularisation of 1º tumour cells leads to the cancer invading the blood vessels
2. this causes tumour cell embolism as the cancer cells circulate the circulatory system
3. tumour cells activate osteoclasts to reabsorb the bone
4. secondary bone tumour is formed

Question 3

What role do intravenous bisphosphanates play in managing secondary bone tumours?

Answer 3

to inhibit osteoclastic resorption of bone

Question 4

What is the pathophysiology of osteosarcomas?

Answer 4

1. malignant osteosarcomas arise from osteoblasts
2. they secrete osteoid
3. then local spread occurs quickly, destroying the cortex

Question 5

How can you spot osteosarcoma on an X-ray?

Answer 5

1. ill-defined lesion with an indistinct zone of transition
2. sclerotic or lytic areas within the lesion
3. cortical destruction
4. codman triangle
5. sunray spicules

Question 6

What is the prognosis of osteosarcoma?

Answer 6

• 5 year survival rate is 60%
• prognosis better in adolescents
• poor prognosis for elderly patients with pagets

Question 7

Why are isotopic bone scans helpful investigations for osteosarcoma?

Answer 7

highlights areas of bony metabolic activity

Question 8

How are osteosarcomas managed?

Answer 8

• preoperative chemotherapy followed by limb salvage surgey
• amputation occasionally required

Question 9

What is codman triangle?

Answer 9

the triangular area of new subperiosteal bone that is created when a lesion raises the periosteum away from the bone.

Question 10

How are secondary bone tumours managed conservatively?

Answer 10

• analgesia
• splintage
• radiotherapy for bony metastatic pain
• chemotherapy

Question 11

what are the 6 tumours most likely to metastasize?

Answer 11

1. breast
2. lung
3. prostate
4. renal
5. thyroid
6. bowel

Question 12

What is the most common malignant primary tumour?

Answer 12

Osteosarcoma

Question 13

Why are bone biopsies not always performed when investigating osteosarcoma?

Answer 13

to avoid the risk of causing seeding in nearby tissues

Question 14

What surgical management is available for secondary bone tumours?

Answer 14

• intramedullary fixation of long bones for fracture (including in palliative care for pain relief)
• joint arthroplasty
• spinal decompression and stabilisation for acute cord compression

Question 15

What is chondosarcoma?

Answer 15

a rare malignant primary bone tumour arising from chondrocyte cells

Question 16

Where do osteosarcomas most commonly arise?

Answer 16

• around the knee
• proximal humerus
• femur

Question 17

How are secondary bone tumours investigated?

Answer 17

• blood tests to identify the primary (CEA or PSA etc.)
• Plain X-ray (osteolytic, sclerotic or mixed lesions)

Question 18

Who are more likely to develop osteosarcoma?

Answer 18

• under 20 years old
• elderly with paget’s disease

Question 19

How are chondosarcomas managed?

Answer 19

wide excision of the lesion is sometimes possible

amputation may be only viable option

chemotherapy and radiotherapy are less effective

Question 20

How is the extent of osteosarcomas determined?

Answer 20

MRI or CT

Question 21

How do secondary bone tumours present?

Answer 21

• bone pain in the axial skeleton
• night pain that does not respond to simple analgesia
• systemic symptoms
• change in neurological signs corresponding to the specific spinal vertebral level affected

Question 22

What is the most common bone-destroying lesion in the older patient?

Answer 22

secondary bone tumours