Aneurysmal Bone Cyst
Exodontia.Info
Useful Websites:

Wikipedia.org

Radiopaedia.org

Dr G's Toothpix


Useful Articles:

Am J Clin Pathol 2007.  Aneurysmal Bone Cyst.  Fine-Needle Aspiration Findings in 23 Patients With Clinical &
Radiologic Correlation

Med Oral Patol Oral Cir Bucal 2007.  Aneurysmal Bone Cyst of the Mandible - Case Presentation & Review of
the Literature

Head & Face Medicine 2009.  Aneurysmal Bone Cyst located in the Mandibular Condyle

J Oral Maxillofac Pathol 2011.  Aneurysmal Bone Cyst of the Mandible.  A Case Report & Review of Literature

J Oral Sci 2011.  Case Report.  Evolution of an Aneurysmal Bone Cyst - A Case Report

Ann Maxillofac Surg 2012.  Giant Recurrent Aneurysmal Bone Cyst of the Mandible

J Orofacial Sci 2012.  Aneurysmal Bone Cyst - Rarity in Mandible & its Ambiguity with Central Giant Cell
Granuloma

Oral Hyg Health 2013.  The Traumatic Etiology Hypothesis of Traumatic Bone Cyst.  Overview & Report of a
Case

J Oral Maxillofac Radiol 2014.  Aneurysmal Bone Cyst of the Mandible.  Report of a Case with a Review of the
Literature

JOMS 2014.  Aneurysmal Bone Cyst of the Jaws Clinicopathological Study

J Ind Acad Oral Med Radiol 2015.  Bilateral Aneurysmal Bone Cyst of the Mandible - A Case Report

J Clin Exp Dent. 2019.  Aneurysmal Bone Cyst of the Mandible with Conservative Surgical Management.  A
Case Report
What are Aneurysmal Bone Cysts?

The Aneurysmal Bone Cyst (ABC) of the jaw is a pseudo-cystic lesion lacking an epithelial lining.  It is a rapidly
growing and destructive bone lesion characterized by replacement of the normal bone with
fibro-osseous tissue
containing blood-filled
sinusoidal / cavernous spaces.  Although the ABC is a benign lesion, it can behave
locally in an aggressive manner locally because of its rapid growth &
osteolytic capacity.  This lesion represents
less than 1% of all
the bone cysts biopsied.

Between 2 - 12% of ABC's
is located at the head and neck region.  From this last group almost 90% of the
cases affect the
posterior mandible (body of the mandible) (40%), ramus (30%), angle (19%), symphysis (9%)
and
condyles (2%).  The median age at diagnosis is 13 years old.  80 % of the patients are under 20 years old.

It is most common in those regions of the skeleton where there is both a relatively high venous and marrow
content.  This explains the rarity of
ABC's in the skull bones, in which there is low venous pressure.


How are they diagnosed?

The radiological features of ABC's in the jaws are quite varied.

The bone is expanded, appears cystic resembling a honeycomb / soap bubble & is eccentrically ballooned.  
There may be destruction / perforation of the cortex and a peri-osteal reaction may be evident.

It may appear
radio-lucent, radio-opaque or mixed.

The diagnosis based on radiographic appearance is impossible because there are other lesions having similar
radiographic appearance, such as
ameloblastoma, myxoma, central giant cell granuloma, odontogenic cysts or
central hemangiomas of the bone.

Histologically,
ABC's are characterised by channels & multi-loculated cyst-like spaces filled with blood & lined by
fibrous septa that may / may not contain osteoclast-like giant cells, osteoid, woven bone & chondroid matrix
material.


What are the signs & symptoms of an Aneurysmal Bone Cyst?

The main symptoms include dull pain ± œdema (swelling).  They usually show rapid growth.  Depending on its
location, other signs / symptoms can be found such as headache,
diplopia (double vision), loss of vision
(blindness),
proptosis (bulging eyes), tooth mobility, hearing loss, etc.

ABC's can be classified into 3 types.

  1. Conventional / Vascular type (95%) manifests as a rapidly growing, expansive, destructive lesion causing
    cortical perforation & soft tissue invasion.
  2. Solid type (5%) may present as a small asymptomatic lesion first noticed as radio-lucency on a routine X-
    ray or as a small swelling.
  3. Mixed variant demonstrates features of both the vascular & solid types.  It may be a transitory phase of the
    lesion because sudden activation / rapid enlargement of stable lesions has been reported.


What are the causes of an Aneurysmal Bone Cyst?

The aetiology of ABC's are unclear and controversial.

Trauma.  Trauma causes an inciting injury to peri-osteal vessels initiating the development of the ABC.  
However, a history of trauma can be difficult to prove in a large number of cases.

Alteration in Local Hæmodynamics.  This causes increased venous pressures and engorgement of the vascular
bed in the transformed bone, leading to resorption, connective tissue replacement, and osteoid formation.  
dilatation of local vascular network due to increased venous pressure caused by local circulatory abnormalities.
causing increased venous pressures and engorgement of the vascular bed in the transformed bone, leading to
resorption, connective tissue replacement and osteoid formation.

Subperiosteal intra-osseous hæmatoma is a secondary phenomena occurring in primary cystic lesions of bone
or tumours.

Reactive malformation

Genetic predisposition.  Some researchers have demonstrated that chromosomal translocation t(16;17) (q22;
p13) is a cytogenic abnormality which could result in the development of ABCs.

They can arise de novo,when they are known as primary ABC, or in co-existence with other lesions such as
ossifying fibroma (OF), chondroblastoma, solitary bone cyst, giant-cell tumour of the bone, osteosarcoma,
osteoblastoma, giant cell reparative granuloma, fibrous dysplasia and fibro-myxoma when they are secondary in
nature

Primary could be congenital or acquired and could originate from pre-existing AV malformations.  The congenital
type is seen in children and young adults with no history of trauma, whereas the acquired type is found in adults
with a history of trauma.

The secondary type is postulated to be associated with degeneration of pre-existing lesions such as a cyst,
tumour or fibro-osseous lesion.  The two lesions could exist independently.


Familial incidence of ABC has also been reported in literature.


How are they treated?

Treatment of ABC is usually directed toward complete removal of the lesion.  This may prove difficult at times
since the lesions are often multi-locular and may be divided by multiple bony septæ.

The treatment modalities include
per-cutaneous sclerotherapy, diagnostic & therapeutic embolisation, curettage,
block resection & reconstruction, radiotherapy & systemic calcitonin therapy.

Self-healing cases have also been reported on long-term follow-up.

Several authors recommend immediate reconstruction of the defect with
auto-genous grafts in cases of æsthetic
deformity, high risk of fractures or loss of
mandibular continuity.

Simple
curettage is associated with high recurrence rates varying from 21 to 50%.



Differential Diagnosis:

  • Ossifying Fibroma
  • Ameloblastoma
  • Giant Cell Granuloma
  • Peripheral & Central Giant Cell Reparative Granulomata
  • Traumatic Bone Cyst
  • Brown Tumor of Hyperparathyroidism
  • Myxoma
  • Fibrous Dysplasia
  • Desmoplastic Fibroma
  • Fibrous Histiocytoma
  • Hæmangioma
  • Osteogenic Sarcoma
  • Globulo-Maxillary Cyst
  • Hæmangio-endothelioma
  • Hæmangio-pericytoma
Last Updated 30th March 2021
An Aneurysmal Bone Cyst (ABC) is a benign cystic lesion of bone, composed of blood-filled
spaces separated by connective tissue
septa (walls) containing fibroblasts, osteoclast-type
giant cells
and reactive woven bone.  It is found more frequently in the mandible (lower jaw)
than the
maxilla (upper jaw) (3:1) with preponderance for the body, ramus and angle of the
mandible.  It affects young persons under 20 years of age with no gender predilection.
X-Rays of Aneurysmal Bone Cysts + CT Scan (Reconstructed) of Aneurysmal Bone Cyst