Benign bone tumours

Question 1

Commonest benign bone tumour

Answer 1

Osteochondroma

Question 2

Describe an osteochondroma

Answer 2

Bony outgrowth on the external surface with a cartilaginous cap.

Question 3

What symptoms do osteochondromas cause?

Answer 3

Sometimes localised pain. Sometimes asymptomatic.

Question 4

Metastatic properties of osteochondromas?

Answer 4

Only a very small 1% chance of metastases.

Question 5

Under what conditions would you perform an excisional biopsy on an osteochondroma?

Answer 5

If it changes in size or produces pain.

Question 6

Multiple osteochondromas?

Answer 6

Rare autosomal dominant hereditary disorder.

Question 7

Enchondroma decription

Answer 7

Usually metaphyseal (narrow part of the bone between the epiphysis and the diaphysis (shaft)) cartilaginous tumour.

Question 8

What is enchondroma caused by?

Answer 8

Failure of normal enchondral ossification at the epiphyseal growth plate.

Question 9

Appearance of enchondroma on Xray

Answer 9

Usually lucent (area that is dark on the Xray) but can undergo mineralisation to produce a patchy sclerotic appearence.

Question 10

Symptoms of enchondroma

Answer 10

Usually asymptomatic and only found incidentally.

However they can weaken the bone resulting in pathological fracture.

Question 11

Where is an enchondroma likely to occur?

Answer 11

Femur, tibia, humerus, small bones of the hands and feet.

Question 12

Treatment of enchondroma

Answer 12

If fracture has occured- wait for it to heal and then curretage (scrape it out) and filled with a bone graft to strengthen the bone.

Question 13

Describe a simple bone cyst

Answer 13

Single cavity benign fluid filled sac in the bone.

Question 14

Cause of simple bone cysts

Answer 14

Probably due to a growth defect in the physis and therefore occur in the metaphyseal region in long bones e.g. proximal humerus and femur.

Question 15

Symptoms of simple bone cysts

Answer 15

May be asymptomatic

However can cause weakness leading to pathological fracture.

Question 16

Treatment of simple bone cysts

Answer 16

Curettage with/without bone strengthening.

Question 17

Describe an aneurysmal bone cyst

Answer 17

Multi-chambered cyst filled with blood or serum. These chambers can be seen on Xray.

Question 18

What causes aneurysmal bone cysts?

Answer 18

Thought to be due to small arteriovenous malformation.

Question 19

Where do aneurysmal bone cysts usually occur?

Answer 19

The metaphyses of many long bones, flat bones and vertebral bodies.

Question 20

Symptoms/signs of aneurysmal bone cysts?

Answer 20

They are locally aggressive which causes cortical expansion and destruction. This causes pain.
Risk of pathological fracture.

Question 21

Treatment of aneurysmal bone cysts?

Answer 21

Curretage and bone strengthening.

Question 22

Describe a giant cell tumour and where it affects?

Answer 22

Locally aggressive tumour which seems to take a liking to the metaphyseal region. Tend to also involve the epiphyses and subchondral bone adjacent to the joint. They occur after the physis have fused and destroy cortex.

Question 23

Which bones do GCTs affect?

Answer 23

Around the knee, in the distal radius. Can occur in other long bones and in the spine.

Question 24

Symptoms of GCTs?

Answer 24

They are painful and can cause pathological fracture.

Question 25

Histology of GCTs

Answer 25

Multi-nucleate giant cells.

Question 26

Xray appearance of GCTs

Answer 26

Soap bubble

Question 27

Metastatic potential of GCT

Answer 27

Considered benign- however 5% can metatasise to the lung.

Question 28

Treatment of GCT

Answer 28

Intralesional excision with use of phenol, bone cement or liquid nitrogen to destroy remaining tumour material and reduce the risk of recurrence.
Very aggressive lesions with cortical destruction may need joint replacement.

Question 29

Describe fibrous dysplasia

Answer 29

Genetic mutation results in lesions of fibrous tissue and immature bone.

Question 30

What does fibrous dysplasia affect?

Answer 30

One bone (monostotic) or multiple (polyostotic)

Question 31

Appearance of affected bone in fibrous dysplasia?

Answer 31

Defective mineralisation may cause angular deformities. The affected bone may also be wider with thinned cortices.

Question 32

Involvement of the femur with fibrous dysplasia

Answer 32

Shepherds crook look.

Question 33

What do bone scans of fibrous dysplasia show?

Answer 33

Intense increase in uptake during development but the lesion usually becomes inactive.

Question 34

Treatment of fibrous dysplasia

Answer 34

Biphosphonates may reduce pain

Pathological fractures will need internal fixation and cortical bone grafts.

Question 35

Describe an osteoid osteoma

Answer 35

Small nidus (site of origin) of immature bone surrounded by an intense sclerotic halo.

Question 36

Who are osteoid osteomas likely to occur in?

Answer 36

Adolescents

Question 37

Common sites of osteoid osteomas

Answer 37

Proximal femur, the diaphysis (shaft) of long bones and the vertebrae.

Question 38

Symptoms of osteoid osteomas

Answer 38

Intense constant pain.

Worse at night- due to intense inflammatory response

Question 39

Treatment of osteoid osteomas?

Answer 39

NSAIDs to reduce pain
May resolve spontaneously over time but could have CT guided radiofrequency ablation
En bloc excision

Question 40

What other diseases present with a lytic lesion?

Answer 40

Brodie’s abscess and hyperparathyroidism.