Descriptive details of aneurysmal bone cyst.

1. ANEURYSMALBONECYST
Dr. FARRUKH JAVEED
NEUROSURGERY JPMC

2. Definition
• An aneurysmal bone cyst is a benign, expansile
lesion with blood filled cavities separated by septa
of trabecular bone or fibrous tissue containing
osteoclast giant cells.
• The term aneurysmal is derived from its
macroscopic appearance – sponge like tumour
containing numerous giant cells.

3. Etiology
 The true etiology of ABCsis unknown.
 It’s believe that ABCs are the result of a
vascular malformation within the bone.

4. Theories
Three commonly proposed theories are as follows:
i. ABCs may arise without evidence of another lesion
are classified as Primary ABCs (65-99%).
ii. ABCs may be caused by a reaction Secondary to
another bony lesion (1-35%) like GCT,
osteoblastoma, chondroblastoma, and
osteogenic sarcoma.
iii. ABCs may arise in an area of previous Trauma.

5. Incidence and Demographics
 ABCis found at anyage
 Around 75%:before 20 yearsand rare after 30 years
 Female: Male = 2 : 1
 Site - can be found in any bone in the body. The
most common location is the metaphysisof long
bones of lower extremity.
 About 12-30% of the ABCs involve the spine that
represents only 1.4 % of primary vertebral column
tumors.

6.  Spine:
 Most common in the thoracolumbar region
 The cervical spine is involved in 30-41 %.
 As with most benign osseous lesions, 60% of
spinal aneurysmal bone cysts occur in the
posterior elements.
 Half of the casesinvolving more than one
vertebra.

7. Presentation
 Patients usually present with pain, a mass, a pathologic
fracture, or combination of these symptoms in the affected
area.
 Neurologic symptoms may develop when involving the nerve,
typically in the spine.
 Other findings may include the following:
• Deformity
• Decreased movement, weakness, or stiffness
• Occasionally, bruit over the affected area
• Warmth over the affected area

8. Histology
 Aneurysmal bone cyst consists of blood-filled spaces of
variable size that are separated by connective tissue
containing trabeculae of bone or osteoid tissue and
osteoclast giant cells.
 They are not lined by endothelium.

9. Development of ABC
It follows 3 stages-
Stage Description
I Initial phase Osteolysis without peculiar findings.
II Growth phase •Rapid increase in size of osseous erosion.
•Enlargement of involved bone.
•Formation of shell around central part of lesion.
III Stabilization phase Fully developed radiological pattern.

10. Imaging Modalities
1. X- ray
2. CT scan
3. MRI
4. Nuclear Imaging
5. Angiography

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

12. Figure: Anteroposterior (A) and lateral (B) cervical spine radiographs.

13. X-ray cervical spine showing destruction of the C3 vertebral body and its posterior
elements.

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

15. Computed tomography of cervical spine with three-dimensional reconstruction
showing destruction of body and posterior elements of C3 vertebra with partial
destruction of body and posterior elements predominantly on the left side of C2
and C4 vertebrae

16. CT scan of aneurysmal bone cyst arising from lamina and internal mass of C6
resulting in a unilateral dislocation of the facet joints in a 10 year old girl.

17. CTof aneurysmalbone cyst.

18. Magnetic Resonance Imaging
• T1WI - show predominantly low to intermediate signal intensity
with or without fluid levels. Acute hemorrhage into the cyst may
have high signal intensity.
• T2WI - show areas of low to intermediate signal intensity or some
areas of heterogeneous high signal intensity, depending on the
contents of the cyst. A rim of low signal intensity with internal septa
may produce a multisystem appearance.
• MRI images of aggressive lesions show tumor enhancement with
gadolinium enhancement, especially when they are associated with
other tumors.

19. • Spinal cord compression and signal-intensity
alteration in the cord can be evaluated when
neurologic symptoms are present.
• Fluid-fluid levels may be seen in the cysts.
• To demonstrate this phenomenon, the patient must
remain motionless for at least 10 minutes before
scanning.

20. Magnetic Resonance Imaging of the cervical spine demonstrating grossly
compressed and collapsed C3 vertebral body with ballooning of the posterior arch
due to a mass extending from C2 to C5. The mass is showing mixed signal intensity in
T1-weighted image (T1-wi), T2-wi and has heterogeneous contrast enhancement.

21. Fluid - fluid level (non specific)
FFLresults from separation of 2 fluids of different densities within a cavernous space
Mnemonic
•
•
•
•
•
•
•
•
G:giant celltumour
O: osteoblastoma
A: aneurysmal bone cyst
T:telangiectatic osteosarcoma
S: sarcomas
C: chondroblastoma
S: solitary bone cyst
F: fibroxanthoma

22. Nuclear Imaging
• Demonstration of a solitary lesion on bone scintigraphy helps
distinguish an aneurysmal bone cyst from other bone tumors,
a hemophilic pseudo tumor, etc.
• Radioisotope uptake is increased.
• The common pattern is the accumulation of the tracer in the
periphery of the lesion, with little intensity in the center; this
finding is present in about 65% of cases.

23. Increased radioisotope uptake peripherally with a photopenic center.
"doughnut sign"

25. Angiography
• On angiograms, ABCsare hypervascular lesions .
• This feature is contrary to that of other malignant lesions, such
as osteosarcoma and chondrosarcoma, which have gross
hyper vascularity.
• Hyper vascular regions in aneurysmal bone cysts may affect
the prognosis, because the number and size of the lesions are
positively correlated with the likelihood of lesional recurrence
after treatment.

26. Angiography examination of ABCof a 13-year-old male showed an expansile
lesion involving the left inferior pubic ramus and ischium.

27. Differential Diagnosis
• Simple bone cyst
- central location, before epiphyseal fusion
- absence of expansion
- lack of cortical discontinuity
• Giant cell tumor of bone
- occurs in patients over age 20 -40 year
- expansile, eccentric, wide zone of transition
- begin in epiphysis with extension into metaphysis
- involves joints or adjacent bone or soft tissue
• Osteoblastoma
- may have a “soap bubble” expansile appearance
- no fluid level on CT/MR
• Fibrous dysplasia
- ground-glass opacities: 56%
- homogeneously sclerotic: 23%
- well circumscribed lesions
- no periosteal reaction
• Chondroblastoma
- arising eccentrically in the epiphysis of long bone
- internal calcifications can be seen in 40-60% cases
- Size ranges from 1-10 cm, most are 3-4 cm at diagnosis
• Chondromyxoid fibroma
• - knee joint (2/3)
- well defined radiolucent, eccentric in metaphysis
- marginal sclerosis

28. Treatment
• Preoperative embolization
• Curettage & bonegrafting
• Complete resection with bone graft
• Radiotherapy
• Steroids & Calcitonin
• The treatment of choice for aneurysmal bone cysts
is gross total resection, which is curative when
feasible.

29. Embolization
• Embolization can be used as first-line and the sole
therapy for ABCs.
• Several successful cures after embolization of ABCs
have been reported.
• In addition, embolization is used preoperatively to
decrease intraoperative blood loss and morbidity.

30. Surgery
• Surgically, complete excision of the tumor
is the goal but may be difficult.
• Incomplete tumor excision may be
associated with significant rates of tumor
recurrence.
• Spinal reconstructions via anterior or
posterior approaches are recommended
when bone removal is extensive.

31. Radiotherapy
• Radiotherapy can be considered in patients with
residual or recurrent tumor.
• ABCs are sensitive to radiation, but the recurrence
rate remains significant despite adjuvant
radiotherapy.
• Usually 26 to 30 Gy are used.

32. Prognosis
 Recurrence rate 20-30%
 Partial resection or curettage has been
associated with recurrence rates as high as 71%.
 Despite high recurrence rates, cases of
spontaneous regression of ABCs have also been
reported

33. Curopsy; (curopsy = biopsy with intention to cure)
• A novel technique called introduced by Reddy and associates from
the United Kingdom in early 2014.
• Curopsy is “a percutaneous-limited curettage at the time of biopsy,
obtaining the lining membrane from various quadrants of the cyst
leading to consolidation”.
• They treated 102 patients with ABCs (most located in the tibia,
femur, and humerus) and reported an 81% resolution rate after a
median of 14 months.
• The group concluded that “curopsy is a simple procedure that offers
diagnostic and therapeutic benefit for many patients with primary
ABCs without any added morbidity.”

34. Case Report: Rare case of an
aneurysmal bone cyst of the skull

35. A 13 years old girl with no significant past medical history
presented with neck pain , without any traumatic history .
On Clinical Examination:
• An adherent posterior cervical swelling with moderate neck
limitation motion without torticollis.
• Neurological examination was normal and no inflammatory
profile was found.
A surgical biopsy was performed by a posterior approach,
histological analysis showed cystic spaces separated by
fibrous septa, confirming the diagnosis of ABC.
Case Report

36. • X-ray of cervical spine showed an expanding trabeculated
osteolytic lesion of C2 spinous process with no soft tissue
involvement.

37. • CT view showed postero-lateral expanding lesion, scalloping of the
upper aspect of C3 spinous process with no periosteal bone reaction.

38. • The MRI showed C2 spinous process osteolytic lesion, fluid-fluid
levels with no spinal cord development.

40. • Halo cast was removed 3 months following surgery. Controlled
radiographs showed progressive ossification of posterior elements
and no instability on dynamic radiographs . No recurrence with 2
years follows up with no longer neck pain.