Bone tumours Flashcards
What benign bone tumours exist?
1: osteochondroma
2: endchondroma
3: simple bone cyst
4: anuerysmal bone cyst
5: giant cell tumour
6: fibrous dysplasia
7: osteoid osteoma
What is an ostreochondroma?
The commonest benign bone tumour
produces a bony outgrowth on the external surface with a cartilaginous cap.
can produce local pain.
There is a very small (1%) risk of malignant transformation and any lesion growing in size or producing pain may require excisional biopsy.
Multiple osteochondromata can occur as an autosomal dominant hereditary disorder.
What is an enchondroma?
intramedullary and usually metaphyseal cartilaginous tumour caused by failure of normal enchondral ossification at the growth plate.
The lesion is usually lucent but can undergo mineralization with a patchy sclerotic appearance.
Many are incidental findings and the lesions are usually asymptomatic but can weaken the bone resulting in pathologic fracture.
Endchondromas can occur in the femur, humerus, tibia and small bones of the hand and feet. Once a fracture has healed or if there is a risk of impending fracture they may be scraped out (curettage) and filled with bone graft to strengthen the bone.
What is a simple bone cyst?
A simple bone cyst (aka unicameral bone cyst) is a single cavity benign fluid filled cyst in a bone. They are probably a growth defect from the physis and are therefore metaphyseal in long bones (usually in the proximal humerus and femur) although they can occur in the talus or calcaneus. They may be asymptomatic and an incidental finding on xray (usually a child or young adult) however they can cause weakness leading to pathological fracture. Again treatment with curettage and bone grafting with or without stabilization may be required.
What is an aneurysmal bone cyst?
An aneurysmal bone cyst in contrast contains lots of chambers which are filled with blood or serum. The different chambers may be seen on xray. They are thought to be due to a small arteriovenous malformation. They can occur in the metaphyses of many different long bones, flat bones (ribs, skull) and vertebral bodies. The lesion is locally aggressive causing cortical expansion and destruction and is usually painful. Again there is a risk of pathological fracture. Treament is again with curettage and grafting or the use of bone cement.
What is a giant cell tumour?
A giant cell tumour of bone can also be locally aggressive and they also have a predilection for the metaphyseal region but tend to involve the epiphysis and can extend to the subchondral bone adjacent to the joint.
GCTs most commonly occur around the knee and in the distal radius but can occur in other long bones, the pelvis and the spine.
They occur after the physis has fused and are locally destructive destroying cortex.
They are painful and may cause pathological fracture.
The aetiology is unknown but as the name suggests histologically they consist of muli‐nucleate giant cells.
On Xray they have a characteristic “soap bubble” appearance. Although they are considered benign, 5% can metastasize to the lung with benign pulmonary GCT.
Treatment is 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.
What is fibrous dysplasia of the bone?
a disease of a bone usually occurring in adolescence where a genetic mutation results in lesions of fibrous tissue and immature bone.
It can affect one bone (monostotic) or more (polyostotic).
Defective mineralization may result in angular deformities and the affected bone is wider with thinned cortices. Stress fractures can occur.
Extensive involvement of the proximal femur can produce a shepherd’s crook deformity.
Bone scans show intense increase in uptake during development but the lesion usually becomes inactive.
Bisphosphonates may reduce pain and pathologic fractures should be stabilized with internal fixation and cortical bone grafts used to improve strength.
Simple intralesional excision alone has a very high recurrence rate.
What is an osteoid osteoma?
An osteoid osteoma is a small nidus of immature bone surrounded by an intense sclerotic halo.
They most commonly occur in adolescence and common sites include the proximal femur, the diaphysis of long bones and the vertebrae.
The predominant clinical feature is intense constant pain, worse at night due to the intense inflammatory response.
This pain is greatly relieved by NSAIDs.
The lesion may be seen on xray however bone scan (intense local uptake) and CT can confirm the diagnosis.
The lesion may resolve spontaneously over time but some cases may require CT guided radiofrequency ablation or en bloc excision.
What is a brodies abscess?
subacute osteomyelitis
What is a brown tumour?
hyperparathryoidism
What do malignant primary bone tumour show on xray?
These show aggressive and destructive signs on x‐ray including:
- cortical destruction,
- a periosteal reaction (raised periosteum producing bone),
- new bone formation (sclerosis as well as lysis from destruction)
- and extension into the surrounding soft tissue envelope.
What is the most common primary bone tumour?
- what age group does this affect?
- what location do these occur?
The most common form of primary bone tumour is osteosarcoma, named according to the fact it is a malignant tumour producing bone. Most cases are seen in younger age groups (adolescence and early adulthood) with 60% involving the bones around the knee. Other sites include the proximal femur, proximal humerus and pelvis.
How does osteosarcoma spread? what is the treatment?
Metastatic spread is usually haematogenous but can be lymphatic. 10% of patients have pulmonary metastases at diagnosis. Whilst they are not radiosensitive, adjuvant chemotherapy can prolong survival.
Chondrosarcoma:
- is this more or less aggressive than osteosarcoma?
- who is affected?
hondrosarcoma is a cartilage producing primary bone tumour and is less common and less aggressive than osteosarcoma. It tends to occur in an older age group (mean age 45).
Where is chondrosarcoma found usually?
They can be very large and are slow to metastasize. They tend to be found in the pelvis or proximal femur. The prognosis is dependant on the histological grade with the majority being low grade. They are not radiosensitive and unresponsive to adjuvant chemotherapy thus far.
