Bone & joints
Other tumors
Aneurysmal bone cyst


Topic Completed: 4 May 2020

Minor changes: 5 August 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

PubMed search: Aneurysmal bone cyst[TI] pathology review[PT]

Elham Nasri, M.D.
John D. Reith, M.D.
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Cite this page: Nasri E, Reith JD. Aneurysmal bone cyst. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneabc.html. Accessed December 4th, 2020.
Definition / general
  • Benign, locally destructive multiloculated blood filled cystic lesion of bone
  • Classified as an osteoclastic giant cell rich tumor (WHO 2020)
  • Primary and secondary forms
  • High rate of local recurrence
Essential features
  • Imaging: multiloculated lesion with fluid-fluid levels, best appreciated on MRI
  • Histology: cyst walls composed of fibroblasts, woven bone and osteoclastic giant cells
  • Molecular: rearrangement of USP6 gene (primary form only)
Terminology
  • Related term: giant cell lesion of small bones
ICD coding
  • ICD-10: M85.50 - aneurysmal bone cyst, unspecified site
Epidemiology
  • Rare; 2.5% of all primary bone tumors
  • M = F
  • More common in skeletally immature patients
Sites
  • Broad skeletal distribution
    • Metaphyseal region of long tubular bones, most commonly the femur, tibia and humerus
    • Posterior elements of vertebrae
Etiology
Clinical features
  • Pain and swelling
  • Pathologic fracture
  • Nerve compression symptoms in cases of vertebral column involvement
Diagnosis
  • Requires correlation of clinical, radiographic and histologic findings to distinguish primary from secondary aneurysmal bone cyst
  • Lack of immunoreactivity for H3G34W (and other histone antibodies) is helpful in excluding giant cell tumor with cystic features
Radiology description
  • Xray:
  • CT scan:
    • Well delineated lytic lesion, usually with thin rim of reactive bone
    • Fluid-fluid levels occasionally visible
  • MRI:
    • Multiloculated cyst with characteristic fluid-fluid levels
  • Isotope scan:
    • Peripheral uptake with central photopenia imparts a donut-like appearances
Radiology images

Contributed by Elham Nasri, M.D.
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Aneurysmal bone cyst of proximal tibia

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Aneurysmal bone cyst of humerus


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Aneurysmal bone cyst of distal tibia

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Aneurysmal bone cyst of calcaneus bone

Prognostic factors
Case reports
Treatment
  • Curettage or en bloc resection
  • Percutaneous sclerotherapy with doxycycline (Bone Joint J 2020;102-B:186)
  • Arterial embolization
  • Steroid or calcitonin injection
Clinical images

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Intraoral tumor

Gross description
  • Spongy, multiloculated, hemorrhagic lesion
  • Variable size
  • Irregular, sharply demarcated borders with thin shell of reactive bone
  • Variable amount of solid component
Gross images

Contributed by Elham Nasri, M.D.
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Blood filled cysts

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Multi loculated cyst

Frozen section description
  • Usually small fragments of cellular septa containing:
    • Fibroblast-like stromal cells lacking cytologic atypia
    • Osteoclast-like giant cells
    • Reactive woven bone
    • Mitotic activity typically present, no atypical mitoses
Frozen section images

Contributed by Elham Nasri, M.D.
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Cystic spaces and stromal giant cells

Microscopic (histologic) description
  • Multiloculated cystic lesion
    • Blood filled cystic spaces separated by cellular septa containing fibroblasts, giant cells and woven bone
    • Calcified, basophilic material (blue reticulated chondroid-like material)
    • Necrosis not common but mitotic activity is easily identified
    • No cytologic atypia (Am J Clin Pathol 2015;143:823)
Microscopic (histologic) images

Contributed by Elham Nasri, M.D.
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Cysts and giant cells

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Blue chondroid like material

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Blood filled cystic spaces

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Solid area of cyst wall

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Reticulated chondroid-like material


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Multiple cystic spaces

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Blood filled cysts

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Reticulated chondroid-like material

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Cyst wall and giant cells

Positive stains
  • There is no specific immunohistochemical stain for aneurysmal bone cyst
Molecular / cytogenetics description
Sample pathology report
  • Mass, distal metaphysis, left tibia, curettage:
    • Aneurysmal bone cyst
Differential diagnosis
  • Telangiectatic osteosarcoma:
    • The most important differential diagnosis
    • Similar architecture but contains anaplastic stromal cells
    • Frequent atypical mitoses
    • No specific diagnostic immunohistochemical stain
    • Lacks USP6 gene rearrangement (Med Pregl 2015;68:127)
  • Central giant cell granuloma:
  • Secondary aneurysmal bone cyst:
    • Lacks USP6 gene rearrangement
    • Extensive sampling is critical to rule out an underlying primary lesion
    • More common in:
Board review style question #1
    Which of the following lesions does not have characteristic rearrangement of USP6 gene?

  1. Giant cell tumor of bone with secondary aneurysmal bone cyst
  2. Myositis ossificans
  3. Nodular fasciitis
  4. Primary aneurysmal bone cyst
Board review answer #1
A. Secondary aneurysmal bone cyst lacks USP6 gene rearrangement.

Comment Here

Reference: Aneurysmal bone cyst (ABC)
Board review style question #2

    The H&E photo belongs to a well defined multiloculated cystic lesion of proximal tibia of a 17 year old boy. FISH analysis is positive for USP6 gene rearrangement. Which is the correct diagnosis?

  1. Aneurysmal bone cyst
  2. Giant cell tumor of bone
  3. Telangiectatic osteosarcoma
  4. Unicameral bone cyst
Board review answer #2
A. Aneurysmal bone cyst. The H&E shows cystic spaces with stromal giant cells. Rearrangement of USP6 gene confirms the diagnosis in the above clinical and radiographic context.

Comment Here

Reference: Aneurysmal bone cyst (ABC)
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