OsteoSarcoma

Question 1

Incidence

Answer 1

○ Rare, however most common primary bone tumour (22%)
○ M/F ratio = 1.5:1
○ Biomodal distribution (age): Main peak in 2nd-3rd decades (10-30yo), second peak >60 (secondary to benign/low grade bone lesion eg Paget’s)

Question 2

Distribution

Answer 2

○ May affect any bone`
○ Usually long bone metaphysis
○ Common in: knee (distal femur?) or proximal humerus

Question 3

Pathology (cells involved)

Answer 3

○ Destroys and replaces bone
○ Results in
■ Bone loss
■ Abnormal new bone - esp. periosteal margins
○ Spreads towards periosteum and surrounding soft tissue
○ May cross the epiphyseal plate
○ Histologically arises from primitive osteoblasts
○ Metastasis occurs early via blood, often to lung

Question 4

Clinical picture

Answer 4

○	Pain first symptom 
■	Constant 
■	Worse at night 
■	Gradually increasing in severity 
○	Lump or swelling 
○	Tenderness
○	Overlying tissues may be inflamed

Question 5

Radiological features – Variable, may observe:

Answer 5

○ Hazy, osteolytic areas (esp. Metaphysis)
○ Dense osteoblastic areas
○ Poor definition of endosteal margin
○ Breaching of cortex (Sunray/sunburst sign)
■ Spread to adjacent tissue
■ New bone extending from cortex
○ Reactive new bone formation (periosteal elevation/Codman’s triangle)
○ Pulmonary metastasis

Question 6

Diagnostic Investigations

Answer 6

○	Serum studies 
■	↑ ESR
■	+/- ↑ serum ALP
○	Blood tests
■	Elevated WBC
○	Bone scan - increased uptake by lesion

Question 7

Treatment

Answer 7

○ Surgical amputation

○ Chemotherapy

Question 8

Aspects of disease

Answer 8

• Incidence
• Distribution
• clinical picture
• pathology
• radiological findings
• diagnostic findings
• treatment