Locally destructive, blood-filled reactive lesions of bone and are not considered to be true neoplasm.

1. Dr. Rabins Kumar Sah
Department of Orthopedics
1st Year Resident
NMCTH, Birgunj
ANEURYSMAL BONE CYST

2.  Locally destructive, blood-filled reactive lesions of bone and
are not considered to be true neoplasm.
 Clinical Presentation
 Etiology:
 Arises spontaneously .
 After degeneration or haemorrhage in some other lesion.
 Sites:
 Any bone may involve.
 most common locations are proximal humerus, distal femur,
proximal tibia, and spine.

3.  Vertebral lesions (15% to 20% located in the posterior
elements with extension into the vertebral body or to
adjacent levels).
 Age: < 20 years old.
 Sex: slight female predominance.
 Symptoms:
 Mild to moderate pain for weeks to several months.
 Rapid growth occur and clinically mimic malignancy.
 Spinal lesions cause neurological deficits or radicular pain.

4.  Radiology:
 X-Ray:
 Expansile lytic lesion that elevates the periosteum, but
remains contained by a thin shell of cortical bone.
 Well-defined margins or a permeative appearance that mimics
a malignancy.
 Growing tubular bone:Eccentrically located in the metaphysis.

5.  Bone scan:
 shows diffuse or peripheral tracer uptake with a central area
of decreased uptake.

6.  CT Scan:
 Helpful in areas of complex anatomy, such as the spine or
pelvis.
 In addition, the thin rim of bone surrounding the cyst can be
identified.

7.  MRI:
 Multiloculated cavities and fluid levels.
 Double-density fluid level and intralesional septations usually
indicates an aneurysmal bone cyst.

8.  Pathology:
 Cyst contain clotted blood, and during curettage bleeding
from the fleshy lining membrane.
 Histologically :
 Lining consists of fibrous tissue with vascular spaces,
deposits of haemosiderin and multinucleated giant cells.
 Closely resemble those of giant-cell tumour and only most
experienced pathologists can confidently make the diagnosis.
 Malignant transformation does not occur.

9. Differential Diagnosis
1. Aneurysmal bone cyst
2. Giant cell tumor.
3. Chondroblastoma.
4. Osteoblastoma.
5. Fibrous dysplasia.
6. Nonossifying fibroma.
7. Chondromyxoid fibroma.

10. Treatment
 Surgical treatment: Extended curettage and grafting with
a bone graft substitute .
 Expendable bones : Marginal resection.
 Spine or pelvis:
 Treated with preoperative embolization to minimize
surgical blood loss .
 Arterial embolization used as definitive treatment of
aneurysmal bone cysts in locations where curettage
extremely difficult.

12.  The recurrence rate after curettage approximately 10%
to 20%.
 Recurrence correlated with age younger than 15 years,
centrally located cysts, and incomplete removal of the
cystic cavity contents.
 Recurrent cysts treated with the same approach as the
primary lesion.

13.  Radiotherapy:
 Low-dose irradiation is effective method of treatment.
 associated with rapid ossification .
 Not used routinely because of the potential for malignant
transformation.

14. References