Articles

Cases

Courses

Aneurysmal bone cyst

Changed by Joachim Feger, 29 Jun 2022

Back to revision history

Disclosures - updated 8 May 2022: Nothing to disclose

Updates to Article Attributes

Body was changed:

Show markup changes

Aneurysmal bone cysts (ABC) are benign expansile osteoclastic giant-cell ~~rich~~-rich bony neoplasms, composed of numerous blood-filled channels and cystic spaces ¹.

Terminology

The terms 'giant cell reparative granuloma of small bone' ^2,3 or 'giant cell lesion of small bone' have been discouraged ¹.

Epidemiology

Aneurysmal bone cysts are rare. They are mostly seen in children and adolescents with ~80% under the age of 20 years ^2,3 but can occur at any age ¹. Both genders are equally affected ¹.

Diagnosis

The definitive diagnosis of aneurysmal bone cysts is based on a combination of typical radiological and pathological features.

Diagnostic criteria

Diagnostic criteria according to the WHO classification of soft tissue and bone tumours (5^th edition) ¹:

a multicystic bone lesion with fluid-fluid levels on imaging
histological evidence that cyst walls are composed of fibroblasts, osteoclastic giant cells, and haemosiderin pigment as well as proof of new bone formation

The following molecular criteria are desirable:

USP6 gene rearrangement

Clinical presentation

Aneurysmal bone cysts commonly present with pain and swelling. On rare occasions, this is the result of a pathologic fracture. If the spine is affected they can present with symptoms related to nerve root compression ^1,3.

Complications

Complications include:

pathologic fracture
nerve compression syndrome
spinal canal stenosis
subarticular zone stenosis with nerve root compression

Pathology

Aneurysmal bone cysts consist of multiloculated blood-filled spaces of variable size separated by sponge-like surrounded by a thin reactive bone formation rich in multinucleated osteoclast-like giant cells ¹.

Location

They are typically eccentrically located in the metaphysis of long bones ¹, adjacent to an unfused growth plate. Although they have been described in most bones, the most common locations are ^3-5:

long bones (~50-65%):
- typically eccentrically located in the metaphysis
- especially femur, proximal tibia and fibula and humerus
spine and pelvis (~20-30%):
- especially posterior elements of the spine with extension into the vertebral body in 40% of cases ⁵
- obturator foramen in pelvic location
short bones of hands and feet: more often with a central location
craniofacial: jaw, basisphenoid, and paranasal sinuses
epiphysis, epiphyseal equivalent, or apophysis: rare but important

Macroscopic appearance

Grossly aneurysmal bone cysts are well-defined multiloculated blood-filled cystic lesions with sponge-like septae and a peripheral component that is surrounded by a reactive thin bony shell ¹.

Microscopic appearance

Histologically aneurysmal bone cysts are characterised by the following ^1,6:

blood-filled cystic spaces separated by fibrous septa
composed of bland fibroblast, multinucleated osteoclastic giant cells
woven bone following the border of the fibrous septa bordered by osteoblasts

The previously termed giant lesion of small bones features the same morphological features as the solid subtype of aneurysmal bone cyst ¹.

Immunophenotype

Aneurysmal bone cysts do not express H3.3pGly34Trp, a feature that can be used to differentiate them from giant cell tumours of bone with aneurysmal bone cyst-like changes ¹.

Genetics

Aneurysmal bone cysts display cytogenetic rearrangements of the USP6 gene. These rearrangements also occur in the aneurysmal bone cysts of the hand and feet but not in lesions of the jawbones ¹.

Radiographic features

Plain radiograph

Radiographs demonstrate a sharply defined, expansile solitary lucent bone lesion, with thin-walled cavities ³.

CT

On CT aneurysmal bone cysts are characterised as lucent bone lesions with a mean density higher than fat ⁷. It might show concerning features such as cortical breach or soft tissue extension ^7,8.

Additionally, CT can demonstrate fluid-fluid levels, which are harder to appreciate than MRI and require viewing with a narrow window width ⁸.

MRI

MRI can demonstrate the characteristic fluid-fluid levels exquisitely as well as identify the presence of a solid component and concerning features suggesting an aneurysmal bone cyst-like appearance of another tumour entity.

The cysts are of a variable signal, with a surrounding rim of low T1 and T2 signals. Focal areas of high T1 and T2 signal ⁴ are also seen presumably representing areas of the blood of variable age (see ageing blood on MRI).

Signal characteristics

T1: variable
T2: hyperintense
T1 (C+): septations may enhance ⁹

It is important to remember that the presence of fluid-fluid levels, although characteristic of aneurysmal bone cysts, is by no means unique to them, and is seen in other lesions as well, both benign and malignant (e.g. giant cell tumours (GCT), chondroblastoma, simple bone cysts and telangiectatic osteosarcomas).

Angiography (DSA)

Aneurysmal bone cysts are poorly vascular ¹⁰.

Nuclear medicine

Bone scan

Doughnut sign: increased uptake peripherally with a photogenic centre.

Radiology report

The radiological report should include a description of the following ⁷:

CT/MRI

imaging characteristics e.g. solitary lucent bone lesion, high T1 or low T1 bone lesion
fluid-fluid levels
location within the bone (eccentric, central)
solid components
concerning features
- cortical involvement
- soft tissue extension
- pathologic fracture
- aggressive periosteal reaction
- surrounding bone marrow oedema
- solid mass ~~like~~-like enhancement

The lesion ~~should~~can be categorised according to the bone reporting and data system as Bone-RADS 4 unless histology has been already obtained ⁷.

Treatment and prognosis

Although they are benign aneurysmal bone cysts can display different clinical natural courses: quiescent, active or aggressive. Thus should be referred to an orthopaedic oncologist ⁷and they have been traditionally treated operatively with intralesional curettage or excision or complete en bloc excision with bone grafting are options ³.

Depending on the type of surgery. The recurrence rate of 15-30% has been described ³. Percutaneous treatment with fibrosing agents has also been performed, either in isolation or as a precursor to surgical excision ^3,11,12. Embolisation is another option ³.

Spontaneous regression may occur rarely or also following partial removal ^3,13.

Malignant transformation has been only observed after irradiation ³.

History and etymology

Aneurysmal bone cysts have been first described by the American bone pathologist Louis Lichtenstein in 1950 ¹⁴.

Differential diagnosis

The differential diagnosis depends on the modality.

On plain radiography (and to a lesser degree CT), the diagnosis includes most of the lesions included in the mnemonic FEGNOMASHIC. Compared to the other lesions in this list, aneurysmal bone cysts are markedly expansile (hence, "aneurysmal") and have a thin cortical shell.

On MRI the differential is much shorter, especially when age, location and plain film appearance are taken into account. The main differential includes both lesions with intrinsic fluid-fluid levels (see fluid-fluid level containing bone lesions) and those from which an aneurysmal bone cyst may arise:

chondroblastoma
fibrous dysplasia
giant cell tumour (GCT)⁴
osteosarcoma: especially telangiectatic osteosarcoma

-<p><strong>Aneurysmal bone cysts (ABC) </strong>are benign expansile osteoclastic giant-cell rich bony neoplasms, composed of numerous blood-filled channels and cystic spaces <sup>1</sup>.</p><h4>Terminology</h4><p>The terms 'giant cell reparative granuloma of small bone' <sup>2,3</sup> or 'giant cell lesion of small bone' have been discouraged <sup>1</sup>.</p><h4>Epidemiology</h4><p>Aneurysmal bone cysts are rare. They are mostly seen in children and adolescents with ~80% under the age of 20 years <sup>2,3</sup> but can occur at any age <sup>1</sup>. Both genders are equally affected <sup>1</sup>.</p><h4>Diagnosis</h4><p>The definitive diagnosis of aneurysmal bone cysts is based on a combination of typical radiological and pathological features.</p><h5>Diagnostic criteria</h5><p>Diagnostic criteria according to the <a title="WHO classification of bone tumours" href="/articles/who-classification-of-tumors-of-bone">WHO classification of soft tissue and bone tumours (5<sup>th</sup> edition)</a> <sup>1</sup>:</p><ul>
+<p><strong>Aneurysmal bone cysts (ABC) </strong>are benign expansile osteoclastic giant-cell-rich bony neoplasms, composed of numerous blood-filled channels and cystic spaces <sup>1</sup>.</p><h4>Terminology</h4><p>The terms 'giant cell reparative granuloma of small bone' <sup>2,3</sup> or 'giant cell lesion of small bone' have been discouraged <sup>1</sup>.</p><h4>Epidemiology</h4><p>Aneurysmal bone cysts are rare. They are mostly seen in children and adolescents with ~80% under the age of 20 years <sup>2,3</sup> but can occur at any age <sup>1</sup>. Both genders are equally affected <sup>1</sup>.</p><h4>Diagnosis</h4><p>The definitive diagnosis of aneurysmal bone cysts is based on a combination of typical radiological and pathological features.</p><h5>Diagnostic criteria</h5><p>Diagnostic criteria according to the <a href="/articles/who-classification-of-tumors-of-bone">WHO classification of soft tissue and bone tumours (5<sup>th</sup> edition)</a> <sup>1</sup>:</p><ul>
~~-<li>histological evidence that cyst walls are composed of fibroblasts, osteoclastic giant cells, haemosiderin pigment as well as proof of new bone formation</li>~~
+<li>histological evidence that cyst walls are composed of fibroblasts, osteoclastic giant cells, and haemosiderin pigment as well as proof of new bone formation</li>
~~-<li>solid mass like enhancement</li>~~
+<li>solid mass-like enhancement</li>
-</ul><p>The lesion should be categorised according to the <a href="/articles/bone-reporting-and-data-system-bone-rads-1">bone reporting and data system</a> as Bone-RADS 4 unless histology has been already obtained <sup>7</sup>.</p><h4>Treatment and prognosis</h4><p>Although they are benign aneurysmal bone cysts can display different clinical natural courses: quiescent, active or aggressive. Thus should be referred to an orthopaedic oncologist <sup>7 </sup>and they have been traditionally treated operatively with intralesional curettage or excision or complete en bloc excision with bone grafting are options <sup>3</sup>.</p><p>Depending on the type of surgery. The recurrence rate of 15-30% has been described <sup>3</sup>. Percutaneous treatment with fibrosing agents has also been performed, either in isolation or as a precursor to surgical excision <sup>3,11,12</sup>. Embolisation is another option <sup>3</sup>.</p><p>Spontaneous regression may occur rarely or also following partial removal <sup>3,13</sup>.</p><p>Malignant transformation has been only observed after irradiation <sup>3</sup>.</p><h4>History and etymology</h4><p>Aneurysmal bone cysts have been first described by the American bone pathologist Louis Lichtenstein in 1950 <sup>14</sup>.</p><h4>Differential diagnosis</h4><p>The differential diagnosis depends on the modality.</p><p>On plain radiography (and to a lesser degree CT), the diagnosis includes most of the lesions included in the mnemonic <a href="/articles/lucentlytic-bone-lesion-differential-diagnosis-mnemonic-1">FEGNOMASHIC</a>. Compared to the other lesions in this list, aneurysmal bone cysts are markedly expansile (hence, "aneurysmal") and have a thin cortical shell.</p><p>On MRI the differential is much shorter, especially when age, location and plain film appearance are taken into account. The main differential includes both lesions with intrinsic fluid-fluid levels (see <a href="/articles/fluid-fluid-level-containing-bone-lesions-2">fluid-fluid level containing bone lesions</a>) and those from which an aneurysmal bone cyst may arise:</p><ul>
+</ul><p>The lesion can be categorised according to the <a href="/articles/bone-reporting-and-data-system-bone-rads-1">bone reporting and data system</a> as Bone-RADS 4 unless histology has been already obtained <sup>7</sup>.</p><h4>Treatment and prognosis</h4><p>Although they are benign aneurysmal bone cysts can display different clinical natural courses: quiescent, active or aggressive. Thus should be referred to an orthopaedic oncologist <sup>7 </sup>and they have been traditionally treated operatively with intralesional curettage or excision or complete en bloc excision with bone grafting are options <sup>3</sup>.</p><p>Depending on the type of surgery. The recurrence rate of 15-30% has been described <sup>3</sup>. Percutaneous treatment with fibrosing agents has also been performed, either in isolation or as a precursor to surgical excision <sup>3,11,12</sup>. Embolisation is another option <sup>3</sup>.</p><p>Spontaneous regression may occur rarely or also following partial removal <sup>3,13</sup>.</p><p>Malignant transformation has been only observed after irradiation <sup>3</sup>.</p><h4>History and etymology</h4><p>Aneurysmal bone cysts have been first described by the American bone pathologist Louis Lichtenstein in 1950 <sup>14</sup>.</p><h4>Differential diagnosis</h4><p>The differential diagnosis depends on the modality.</p><p>On plain radiography (and to a lesser degree CT), the diagnosis includes most of the lesions included in the mnemonic <a href="/articles/lucentlytic-bone-lesion-differential-diagnosis-mnemonic-1">FEGNOMASHIC</a>. Compared to the other lesions in this list, aneurysmal bone cysts are markedly expansile (hence, "aneurysmal") and have a thin cortical shell.</p><p>On MRI the differential is much shorter, especially when age, location and plain film appearance are taken into account. The main differential includes both lesions with intrinsic fluid-fluid levels (see <a href="/articles/fluid-fluid-level-containing-bone-lesions-2">fluid-fluid level containing bone lesions</a>) and those from which an aneurysmal bone cyst may arise:</p><ul>

ADVERTISEMENT: Supporters see fewer/no ads

{"current_user":null,"inclusions":[{"imageId":564337,"studyId":11550,"caseSlug":"aneurysmal-bone-cyst-3","caption":"Case 1: proximal humerus","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/564337/0fc3a4ee8e20ea78fd5c7fa08a3834_big_gallery.jpg"},{"imageId":133409,"studyId":8321,"caseSlug":"aneurysmal-bone-cyst-20","caption":"Case 2: distal tibia","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/133409/62b96803d26fe69e35fe817985baa5a50f326f6011e36d03db33f31152891659_big_gallery.jpeg"},{"imageId":17988797,"studyId":44452,"caseSlug":"aneurysmal-bone-cyst-of-the-4th-metacarpal-bone","caption":"Case 3: 4th metacarpal bone","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/17988797/748313f6d18ecafcdb62ed20a0cf33965cc5ad80d210d16be446d1c358982a91_big_gallery.jpeg"},{"imageId":59147648,"studyId":124222,"caseSlug":"vertebral-aneurysmal-bone-cyst","caption":"Case 4","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/59147648/9d0ba3c5054effda94a1a3f2ace02f579b83b7f3fcdd2b64a6cede35d5f22727_big_gallery.jpeg"},{"imageId":564336,"studyId":11549,"caseSlug":"aneurysmal-bone-cyst-2","caption":"Case 5: 4th metacarpal","isStack":false,"diagnosticCertainty":"probable","thumbnail":"https://prod-images-static.radiopaedia.org/images/564336/83fbdf50b24024421bb141e5e4458e_big_gallery.jpg"},{"imageId":23702,"studyId":7441,"caseSlug":"aneurysmal-bone-cyst-radius","caption":"Case 6","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/23702/1fd8e2dce1c8923473d44b0e37cb5e_big_gallery.jpeg"},{"imageId":133133,"studyId":8314,"caseSlug":"giant-cell-tumour-with-aneurysmal-bone-cyst-of-sacrum","caption":"Case 7: with associated GCT","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/133133/8e921a5313194346c2007a83150296_big_gallery.jpg"},{"imageId":133367,"studyId":8319,"caseSlug":"aneurysmal-bony-cyst-humerus","caption":"Case 8","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/133367/6a30c6f4e33b681e04bbb5a9821f6e_big_gallery.jpg"},{"imageId":1226702,"studyId":14240,"caseSlug":"aneurysmal-bone-cyst-abc-1","caption":"Case 9: CT proximal fibula","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/1226702/8b8b225737962887621fdd7a167298_big_gallery.jpg"},{"imageId":1695944,"studyId":16312,"caseSlug":"aneurysmal-bone-cyst-sacrum","caption":"Case 10: sacrum","isStack":false,"diagnosticCertainty":"probable","thumbnail":"https://prod-images-static.radiopaedia.org/images/1695944/ce9bf6c6b3a1c815b43c3e31fd2394_big_gallery.jpg"},{"imageId":1738770,"studyId":16570,"caseSlug":"aneurysmal-bone-cyst-7","caption":"Case 11","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/1738770/2c0f9e8e7016eecc3afc995ffe9c24_big_gallery.jpg"},{"imageId":2328807,"studyId":19364,"caseSlug":"aneurysmal-bone-cyst-abc-tibia","caption":"Case 12: proximal tiba","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/2328807/2f29a611a0fcd286ea16986f91e8b66140bcb0a56567ed2a287d279ef58c46b9_big_gallery.jpeg"},{"imageId":2476284,"studyId":19983,"caseSlug":"aneurysmal-bone-cyst-at-greater-trochanter","caption":"Case 13","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/2476284/158c720725316427657eb59e029f81_big_gallery.jpg"},{"imageId":2533000,"studyId":20150,"caseSlug":"aneurysmal-bone-cyst-of-talus","caption":"Case 14: talus","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/2533000/d7afc72bba6a31d074d39a3aab8505_big_gallery.jpg"},{"imageId":3097736,"studyId":22367,"caseSlug":"aneurysmal-bone-cyst-tibia","caption":"Case 15","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/3097736/83b172eb12cb8930de4569dc319e44_big_gallery.jpg"},{"imageId":3372292,"studyId":22996,"caseSlug":"aneurysmal-bone-cyst-8","caption":"Case 16","isStack":true,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/3372292/be7b6be21d650e4ffa8ae6b0c3a821_big_gallery.jpg"},{"imageId":420395,"studyId":10103,"caseSlug":"aneurysmal-bone-cyst","caption":"Case 17: vertebral","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/420395/739a93662cd57a6dc02cc5339accc3_big_gallery.jpg"},{"imageId":4157136,"studyId":23884,"caseSlug":"aneurysmal-bone-cyst-of-the-calcaneus","caption":"Case 18: arising in the calcaneus","isStack":true,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/4157136/0ec455bf92850025243971ce6b7878_big_gallery.jpg"},{"imageId":4194883,"studyId":23968,"caseSlug":"small-aneurysmal-bone-cyst-of-the-rib","caption":"Case 19: small aneurysmal bone cyst involving rib","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/4194883/de8f973708a68ea2dcc5f28744fa43_big_gallery.jpg"},{"imageId":5143250,"studyId":26094,"caseSlug":"aneurysmal-bone-cyst-of-ischium","caption":"Case 20","isStack":true,"diagnosticCertainty":"probable","thumbnail":"https://prod-images-static.radiopaedia.org/images/5143250/1d7486b50979b6158fc7b8fbc2a335_big_gallery.jpeg"},{"imageId":55894425,"studyId":111086,"caseSlug":"aneurysmal-bone-cyst-cervical-spine","caption":"Case 21: cervical spine","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/55894425/Anonymize.Seq1.Ser1.Img1_big_gallery.jpeg"},{"imageId":6784905,"studyId":29354,"caseSlug":"aneurysmal-bone-cyst-12","caption":"Case 22","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/6784905/be9722d917556399d9a39e943d8309_big_gallery.jpg"},{"imageId":7056742,"studyId":29721,"caseSlug":"aneurysmal-bone-cyst-t11","caption":"Case 23","isStack":true,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/7056742/e6ded0c9a2f6b447ac46ea2f91e51d_big_gallery.jpg"},{"imageId":6913578,"studyId":29395,"caseSlug":"ethmoidal-aneurysmal-bone-secondary-to-an-ossifying-fibroma","caption":"Case 24","isStack":true,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/6913578/41b32a9e9df96f8d26ee9cacaabc34_big_gallery.jpg"},{"imageId":8871725,"studyId":32195,"caseSlug":"aneurysmal-bone-cyst-13","caption":"Case 25","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/8871725/4e2b3df7ab147956bfd8fc36e9ce65_big_gallery.jpg"},{"imageId":12761509,"studyId":38578,"caseSlug":"aneurysmal-bone-cyst-of-the-talus","caption":"Case 26","isStack":true,"diagnosticCertainty":"probable","thumbnail":"https://prod-images-static.radiopaedia.org/images/12761509/c30be722d98e443cb0c476fe3177d7_big_gallery.jpg"},{"imageId":14071547,"studyId":39906,"caseSlug":"mazabraud-syndrome-4","caption":"Case 27: secondary to fibrous dysplasia","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/14071547/7a4aaebdc56c2b00150b833593ebd2_big_gallery.jpg"},{"imageId":51437637,"studyId":80644,"caseSlug":"aneurysmal-bone-cyst-31","caption":"Case 28","isStack":true,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/51437637/61cff2f6b133ec9629947957a03a9dcef2d83eff400834ab81442d2314bcacbf_big_gallery.jpeg"},{"imageId":554015,"studyId":11403,"caseSlug":"aneurysmal-bone-cyst-5","caption":"Case 29: left iliac bone","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/554015/e2ed70b4d246bf1065ac5a79d0fe93b3d6affed483d9fd2df7407158b4a6362a_big_gallery.jpeg"},{"imageId":52448137,"studyId":88327,"caseSlug":"aneurysmal-bone-cyst-of-the-proximal-femur","caption":"Case 30: proximal femur","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/52448137/2d11633ef7570a29808b4c8bd870c9_big_gallery.jpeg"},{"imageId":64061155,"studyId":144045,"caseSlug":"aneurysmal-bone-cyst-43","caption":"Case 31: distal tibia","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/64061155/54a0ef9655400e6ddc47ed49559daf019340c97f50651371f8b476e141c704e3_big_gallery.jpeg"}],"ddx_inclusions":[{"imageId":224,"studyId":8295,"caseSlug":"non-ossifying-fibroma-nof","caption":"Non-ossifying fibroma","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/224/806069f489aa52c31200f2fa4798b3_big_gallery.jpeg"},{"imageId":130247,"studyId":8253,"caseSlug":"giant-cell-tumor-16","caption":"Giant cell tumour: probable","isStack":false,"diagnosticCertainty":"probable","thumbnail":"https://prod-images-static.radiopaedia.org/images/130247/501d480a68a8253a7ab9f9be756a6d_big_gallery.jpg"},{"imageId":53725636,"studyId":98502,"caseSlug":"unicameral-bone-cyst-11","caption":"Unicameral bone cyst","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/53725636/IMG-0015-00011_big_gallery.jpeg"},{"imageId":65142715,"studyId":147941,"caseSlug":"pseudotumour-of-the-calcaneus","caption":"Pseudotumour of the calcaneus","isStack":false,"diagnosticCertainty":"confirmed_substantiated","thumbnail":"https://prod-images-static.radiopaedia.org/images/65142715/ce3c4c72484e4d71efaaa12a4bef8aee4fc6199157b3a40615bba50b3b171638_big_gallery.jpeg"}],"lang":"gb"}

Updating… Please wait.

Unable to process the form. Check for errors and try again.

Thank you for updating your details.