Cancer

Question 1

Which cancers commonly metastasise to bone?

Answer 1

BLTKP

Breast (mixed) 
Lung (lytic) 
Thyroid (lytic) 
Kidney (cannon ball mets in lung) 
Prostate (sclerotic) 

+ astrocytoma

note: lytic lesion usually secondary, sclerotic lesion usually primary

Question 2

What are the differentials for a young patient with bone mets?

Answer 2

• testicular cancer
• nephroblastoma
• leukaemia/lymphoma
• neuroblastoma

Question 3

What are the different types of primary bone tumours?

Answer 3

22% osteosarcoma = distal femur and proximal tibia
10% chondrosarcoma = axial skeleton
8% Ewing’s sarcoma = children

Question 4

What is Mirel’s score for pathological fractures?

Answer 4

Site:

• upper limb = +1
• lower limb = +2
• peri-trochanteric = +3

Pain:

• mild = +1
• moderate = +2
• weight-bearing = +3

Lesion:

• sclerotic = +1
• mixed = +2
• lytic = +3

Size:

• <1/3 = +1
• 1/3-2/3 = +2
• > 2/3 = +3

8-9/16 indicates prophylactic fixation

Question 5

Describe the features of osteosarcoma.

Answer 5

~60%-70% 5yr survival
Adolescents and 70yrs+

Metaphysis and junction between metaphysis and diaphysis

Increased risk of developing Li-Fraumeni syndrome

Ix: CXR/chest CT, CT-guided biopsy

Mx: neoadjuvant chemotherapy, surgery

Question 6

Describe the features of Ewing’s sarcoma.

Answer 6

15ys-25yrs

Diaphysis of long bones

X-ray has onion-skin appearance due to raised periosteum