Week 1 - E - Benign bone tumours - Osteo/enchondroma, simple/aneurysmal cyst, giant cell, fibrous dysplasia, osteoid osteoma Flashcards
Are malginant primary bone tumours rare or common? Are metastatic bone tumours rare or common?
Malignant primary bone tumours are considered very rare when alongside other forms of primary malignancy
Metastatic bone tumours on the other hand are common
What is the commonest benign bone tumour?
The commonest benign bone tumour is an osteochondroma - this is an overgrowth of cartilage and bone
Where in the bone do osteochondromas typically occur? What forms over the osteochondroma?
Osteochondromas typically occur on the external surface of the bone near the growth plate and they have a cartilaginous cap
How do osteochondromas present? What is the risk of malignant trasnformation?
Osteochondromas typically present as a painful mass
The risk of malignant transformation is small at 1%
What do osteochondromas look like on xray?
On Xray the osteochondromas appear as a bony spur arising from the cortex and usually pointing away from the joint
How are osteochondromas managed?
In most cases of osteochondroma, no treatment is required other than regular monitoring of the tumor to identify any changes or complications.
Surgical excision is usually only required if the lesion is growing or producing symptom eg pain or pressing on adjacent structure
What is an enchondroma? What does it originate from?
An enchondroma is an intramedullary and usually metaphyseal bone tumour that originates from cartilage
What causes the enchrondroma to form from the cartilage?
The enchondroma forms due to failure of normal endochondral ossification of the cartilaginous growth plate
How are enchrondromas usually picked up?
Most enchondromas are incidental findings and the lesions are asymptomatic however they can weaken the bone resulting in a pathological fracture
How do enchrondomas appear on xray?
The lesion is usually lucent however can undergo mineralisation with a patchy sclerotic appearance - appear as an intramedullary lesion
What is the treatment of an enchondroma?
Treatment of enchondroma may involve surgery - once a fracture has healed or if there is risk of impending fracture, the enchondroma may be scraped out (curettage) and filled with bone graft to strengthen the bone
What are simple bone cysts also known as? What is a simple bone cyst?
Simple bone cysts are also known as unicameral bone cysts
They are a single cavity benign fluid filled cyst in bone
Where do simple bone cysts typically occur? How do simple bone cysts look on xray?
It usually occurs in the long bones near a joint and growth plate - at the metaphyses such as proximal humerus or proximal femur
On xray they appear less dense than bone as fluid filled in the metaphyseal region
What age group do simple bone cysts tend to affect and how do they present?
They typically occur in children or young adults Simple bone cysts may be asymptomatic and an incidental finding on xray however they can cause weakness leading to pathological fracture
How are simple bone cysts treated?
Simple bone cysts are treated again with curettage and bone grafting to strengthen the bone
What is an aneursymal bone cyst? Why is its name a misnomer?
An aneurysmal bone cyst is a benign, blood-filled lesion in the bone that tends to expand or grow.
While it is referred to as a cyst, it is a misnomer as it is a true benign bone tumor surrounded by a thin wall of bone
What is thought to cause the aneursymal bone cyst?
Aneurysmal bone cyst is thought to be due to a small arteriovenous malformation
Which bones are typically affected by aneursymal bone cyst? Why is this type of bone tumour potentially worrying?
Aneurysmal bone cysts occur in the metaphyses of many different long bones, as well as flat bones (ribs and skull) and vertebral bodies
They are worrying as they are locally aggressive causing cortical expansion and destruction and are usually painful
What is the treatment of aneurysmal bone cysts?
Treatment like enchondromas, and unicameral bone cysts is with curettage and filling with bone graft to strengthen the bone
What is a giant cell tumour of the bone?
Giant cell tumour of the bone is a relatively uncommon tumor of the bone characterised by multinucleated giant (Osteoclast like) cells (hence also called osteoclastoma)
Which region of the bones do giant cell tumours typically affect? and which bones?
Giant cell tumours typucally 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 - can occur in other long bones
How does giant cell tumours of the bone present and what is found histologically?
Giant cell tumours present painfully and may cause pathologically fracture
The aetiology is unknown but as the name suggests histologically they consist of muli‐nucleate giant cells.
What is the appearance seen on ray of giant cell tumours?
Giant cell tumours have the characteristic soap bubble appearance on xray
Describe the difference in where simple bone cysts, aneursymal bone cysts and giant cell tumours expand
Simple bone cysts occur at the metaphyses of long bones and fills the medullary cavity
Aneursymal bone cysts occur in the metaphyses as well and expand the cortical bone
Giant cell tumours involve the metaphyseal region but tend to involve the epiphyses & subchodnral bone at the joints
What percentage of giant cell tumours metastasise and do they become benign or malignant?
Although they are considered benign, 5% can metastasize to the lung with benign pulmonary GCT
What is the treatment of giant cell tumours?
Treatment is intralesional excision with use of phenol, bone cmeent or liquid nitrogen to destroy remaining tumour material and reduce the risk of recurrence
What happens in fibrous dysplasia of the bone?
Fibrous dyspasia of a bone is a disorder where a genetic mutation results in normal bone and marrow being replaced by lesions of fibrous tissue resulting in formation of bone that is weak and prone to expansion
What is it known as when fibrous dysplasia of bone affects * One bone * More than one bone What age group does it tend to present at?
Affecting one bone - monostotic
Affecting more than one bone - polystotic
What does the defective mineralisation of the bone in fibrous dysplasia result in?
Defective minerlisation results in angular deformities and the affected bone is wider with thinner cortices
What is the presentation of fibrous dysplasia of the bone?
Typically presents with pain and increased risk of fracture
What can extensive involvement of the proximal femur in fibrous dysplasia produce?
Shepherd’s crook deformity of the bone
What is the treatment of fibrous dysplasia of the bone?
Biphosphonates may reduce pain
Pathological fractures should be stabilised with internal fixation and cortical bone grafts used to improve strength
What is an osteoid osteoma?
An osteoid osteoma is a benign bone tumor that arises from osteoblasts
Which age group is affected typically by osteoid osteomas and which bones?
Typically occurs in adolescence and affects the long bones esp the proximal femur
What are the presenting features of an osteoid osteoma?
Predominant clinical feature is intense constant pain, worse at night due to the inflammatory response
What do osteoid osteomas look like on radiographs? What confirms diagnosis?
On radiographs, ostoeid osteomas appaer as a small nidus of immature bone (osteoblasts) surrounded by a intense sclerotic halo
Diagnosis is confimed by bone scan (intense local uptake) and CT scan
How are osteoid osteomas treated?
Pain is greatly reliaved by NSAIDs
CT radiofreqnecy abalation is the treatment of choice
Brodie’s abscess and Brown tumours can present with a lytic lesion of bone. What are these conditions?
Brodie’s abscess is a rare form of osteomyelitis. (subacute osteomyeleitis) It involves a subacute infection of the bone with development of a localized abscess, usually within the metaphysis of long bones
Brown tumours form in hyperparathyroidism due to excessive osteoclast activity
