Aneurysmal bone cysts are non-neoplastic, blood-filled lesions of bone that typically affect people under 30 years old. They most commonly occur in the proximal humerus, distal femur, proximal tibia, and spine. On imaging, they appear as an expansile, osteolytic lesion with thinning of the bone cortex. Treatment depends on the activity of the lesion and can include percutaneous sclerotherapy, curettage with bone grafting, or en bloc resection. Curettage with adjuvants has traditionally been the standard treatment but has risks of recurrence or growth plate damage.

2. Defenition
 They are cysts which is locally
destructive, blood-filled reactive
lesions of bone and are not
considered to be true
neoplasms.
 The term aneurysmal derived
from its macroscopic
appearance- sponge like
tumour with numerous giant
cells.

3. Etiology
 It was first recognized by Jaffe and
Lichtenstein(1942)
 True etiology of ABC is not known.
 It is not a cyst and is called an aneurysm
(quite wrongly) only due to characteristic
of expanding the bone into “aneurysm”
shape and that it is filled with blood

4. Incidence and
Demographics
 ABC is found at any age
 Around 75% before 20 years and rare after
30 years.
 Female : Male :: 2:1
 Any bone may be involved, but the most
common locations include the proximal
humerus , distal femur , proximal tibia, and
spine
 Around 12-30% of ABCs involve spine that
represents only 1.4% of Primary vertebral
column tumours

5. Primary ABCs
 They are driven by upregulation of
the ubiquitin-specific
protease USP6 (Tre2) gene on 17p13
when combined by a translocation with a
promoter gene.
 Most commonly described
translocation t(16;17)(q22;p13) leading
to juxtaposition of promoter region
CDH11 on 16q22

6. Secondary ABCs
 Not considered a neoplasm because no
known translocation has been identified
 It can be associated with other tumours.

7.  Associated with other tumours (30% of
times)
 Giant cell tumor (GCT) of bone
 Fibrous dysplasia
 Chondroblastoma
 Osteoblastoma
 Nonossifying fibroma (NOF)
 Fibrous histiocytoma
 Chondromyxoid fibroma
 Simple bone cyst
 Giant cell reparative granuloma
 Telangiectatic osteosarcoma

8. Epidemiology
 75% of patients are < 20 yrs.
 Anatomical location
 ~15% seen in spine
 >60% in long bones (Femur and tibia being
most common)
 51% occurrs in the lower extremities, 22.5% in
upper extremities
 Usually in Metaphysis
 Metatarsal and Calcaneus are the most
common locations in the foot

9. Epidemiology
 Spine :
 Most commonly in
thoracolumbar region
 Cervical spine involved in 30-
40%
 60 % of anuerysmal bone cyst
occur in posterior elements
 Half of the cases involve more
than 1 vertebra

10. Presentation
 Patients usually presents with pain ,mass, a
pathological fracture or a combination of all in
the affected area.
 Neurological symptoms may develop involving
nerve typically in spine.
 Other findings include:
 Deformity
 Decreased movement ,weakness or stiffness
 Warmth over affected area

11. Clinical Features
 Patients commonly have pain and swelling at the
site
 Neurological symptoms may be seen as primary
complaint in ABCs affecting the vertebrae
 Unusually patients may present with a pathological
fracture at the site of ABC

12. Gross Pathology
 Specimens reveal a
thin osseous shell
surrounding a
honeycombed
sponge-like mass
filled with blood

13. Histology
 ABCs consists of blood-filled
spaces variable size that are
separated by connective tissue
containing trabeculae of bone
oseoid tissue and osteoclast giant
cells.
 They are not lined by endothelium.
 Cavity lining by numerous benign
giant cells / spindle cells / thin
strands of woven (new) bone
present

14. Development of ABC
 It follows 3 stages
 Initial phase :
○ Osteolysis without peculiar findings.
 Growth phase:
○ Rapid increase in size of osseous erosion.
○ Enlargement of involved bone.
○ Formation of shell around central part of
lesion.
 Stabilization phase
○ Fully developed radiological pattern.

15. Imaging Modalities
 X-Ray
 CT scan
 MRI
 Nuclear Imaging
 Angiography

16. X-Ray Appearance
 ABC is normally placed in the
metaphysis and appears as a osteolytic
lesion. The periosteum is elevated and
the eroded to a thin margin.
 The expansile nature of the lesion is
often refleced by a "blown-out" or "soap
bubble” appearance.
 The lesion rarely penetrates the articular
surface or growth plate.

18. Evolution of ABCs
(Radiologically)
 Incipient phase (incidentally found): There is a small
nonexpansile intramedullary lytic lesion with distinctive
elevation of periosteum
 Growth phase: Rapid growth and lysis of bone that present
as cortical blowout in “accelerated” phenomenon of ABC
The Codman’s triangles may be prominent at the ends
 Stable phase: Expanded bone with a “shell” around the
lesion along with trabeculations coursing within it (coarse
soap-bubble appearance)

19. Evolution of ABCs
 Stable phase: Expanded bone with a “shell” around the lesion
along with trabeculations coursing within it (coarse soap-bubble
appearance)
 The Healing Cyst:(self-resolution or
following treatment)shows progressive
ossification, resulting in a coarsely
trabeculated bony mass often with
mineralized matrix
 The cyst may invaginate into normal bone
and to epiphysis through growth plate or
extend into soft tissue

20. Capanna et al. described five“morphologic types”
based on the radiographic findings:
 Type I: Central metaphyseal lesion well-contained within bone with intact
bone cortices.
 Type II: Lesion gives an inflated appearance to bone with cortical thinning.
 Type III: Eccentric metaphyseal location with unaffected cortex.
 Type IV: Subperiosteal extension but cortex intact rarely seen in the
diaphysis.
 Type V: Metadiaphyseal location blowout appearance, cortical breach
present and cyst may invaginate into nearby bone

21. Capanna et al. Classification based on
Morphology

22. Computed Tomography
(CT)
 Cross-sectional CT is the most useful
imaging examination, It can demonstrate
the intraosseous and extraosseous lesion.
 CT can be used to determine the nature of
the matrix of especially when tumors are in
complex locations, such as facial skeleton,
spine, thoracic cage, and pelvis.
 Spinal CT can demonstrate stenosis of the
spinal canal due to involvement of the
posterior elements.

24. 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 tumor entity.

25. MRI
Demonstrates the typical blood fluid levels seen on
an MRI scan of ABC

26. Treatment
 The treatment options are multiple and best one
for a patient needs to be individualized
 The inactive cysts have complete periosteal shell
and sclerotic bone margins
 The active cysts have incomplete shell and
aggressive lesions have indefinite margins
 Inactive lesions :spontaneous regression seen
 Active and aggressive ABCs- NEED TREATMENT

27. Percutaneous methods
 For Inducing sclerosis in the cyst and secondary
mineralization (healing)
○ They have advantage particularly in the juxtaphyseal location
and difficult surgical sites
○ Alcoholic solution of zein has shown good result
○ Side effects :percutaneous fistulation, local abscess
formation, and sometimes embolization is seen.
 Healing takes 6–18 months depending on the size of initial lesion
 Percutaneous methods not to be used in patients
 with rapid expansion
 impending fractures
 patients allergic to drug.

28.  Percutaneous
sclerotherapy with
Polidocanol is a safe
alternative to conventional
surgery for the treatment of
an aneurysmal bone cyst.
It can be used at
surgically-inaccessible
sites and treatment can be
performed on an out-
patient basis.

29. Demineralized bone particle
 It is instilled into the lesion as a paste of allogenic
bone powder and autogenous bone marrow to
induce healing.
 No curettage or extensive surgery is done
 It is expected that the bone grafting material
promotes ossification at a pace faster that the
native rate of ABC expansion

30. Curettage and Bone
Grafting
 It had been the gold standard of treatment that is
still used to compare efficacy of other methods
 It is supplemented with the use of high-speed burr,
or extended curettage with adjuvants [peroxide,
phenol, cryotherapy, zinc chloride,hypochlorite,
PMMA to reduce recurrence rate
 Selective arterial embolization has been used for
reducing the blood loss in large cysts but should
not be used to rely upon for inducing healing
 Growth plate can get damaged while treating the
juxtaphyseal lesions

31. Curettage and Bone
Grafting

32. Curettage and Bone
Grafting
Complication of curettage and bone grafting for ABC : The growth plate got
damaged during the index lesion leading to premature fusion and growth
abnormalities of the bone

33. Marginal en bloc resection
 It can be done in
expendable bones (fibula,
clavicle, rib, pubic ramus)
 It has got the lowest
recurrence rates.
 Sub periosteal resection is
possible in children which
can be simultaneously
reconstructed with
fibula

34. Radiation therapy
 It has been found effective in inducing healing and
ossification
 It should be abandoned for high likelihood of
inducing radiation sarcoma

35. Solid ABCs
 A third variant called “solid” ABC have been
described(coined by Sanerkin et al.) in 1983
Containing , lacy, chondroid like material seen in
conventional ABC, but without the typical vascular
and cyst like cavities.
Represent 5–10% of the ABCs
 Nevertheless a fourth variant called the “soft tissue
ABCs” has also been reported

36. REFERENCE
 Campbell’s Operative Orthopaedics
 Apley & Solomon’s System of
Orthopaedics and Trauma
 Essential Orthopaedics by Manish Kumar
Varshney
 Orthobullets.com

37. THANK YOU