bone tumours

Question 1

Osteoma

Answer 1

benign ‘overgrowth’ of bone, most typically occuring on the skull
associated with Gardner’s syndrome (a variant of familial adenomatous polyposis, FAP)

Question 2

Osteochondroma (exotosis)

Answer 2

most common benign bone tumour
more in males, usually diagnosed in patients aged < 20 years
cartilage-capped bony projection on the external surface of a bone

Question 3

Giant cell tumour

Answer 3

tumour of multinucleated giant cells within a fibrous stroma
peak incidence: 20-40 years
occurs most frequently in the epiphyses of long bones
X-ray shows a ‘double bubble’ or ‘soap bubble’ appearance

Question 4

Osteosarcoma

Answer 4

most common primary malignant bone tumour
seen mainly in children and adolescents
occurs most frequently in the metaphyseal region of long bones prior to epiphyseal closure, with 40% occuring in the femur, 20% in the tibia, and 10% in the humerus

x-ray shows Codman triangle (from periosteal elevation) and ‘sunburst’ pattern
mutation of the Rb gene significantly increases risk of osteosarcoma (hence association with retinoblastoma)

other predisposing factors include Paget’s disease of the bone and radiotherapy

Question 5

Ewing’s sarcoma

Answer 5

small round blue cell tumour
seen mainly in children and adolescents
occurs most frequently in the pelvis and long bones. Tends to cause severe pain
associated with t(11;22) translocation which results in an EWS-FLI1 gene product
x-ray shows ‘onion skin’ appearance

Question 6

Chondrosarcoma

Answer 6

malignant tumour of cartilage
most commonly affects the axial skeleton
more common in middle-age