Aneurysmal bone cyst

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Aneurysmal bone cyst
Classification and external resources
The ABC is located on the left, on the fifth metatarsal. Notice that the bone appears to be missing on the x-ray.
ICD-10 M85.5
ICD-9 733.22
eMedicine radio/26 
MeSH D017824

An aneurysmal bone cyst is an expansile osteolytic lesion with a thin wall, containing blood-filled cystic cavities. The term aneurysmal is derived from its radiographic appearance.

Contents

Causes

Trauma is considered the initiating factor in the development of some cysts, in documented cases involving an acute fracture. Local alterations in the blood flow are related to obstructions that are important in the development of an aneurysmal bone cyst.

The lesion generally arises in a pre-existing bone tumor, this is because of the abnormal bones changes in hemodynamics. An aneurysmal bone cyst can arise from a pre-existing chondroblastoma, a chondromyxoid fibroma, an osteoblastoma, a giant cell tumor, or fibrous dysplasia. A giant cell tumor is the most common cause, occurring in 19% to 39% of cases. Less frequently, it results from some malignant tumors, such as osteosarcoma, chondrosarcoma, and hemangioendothelioma.

Effects

Aneurysmal bone cysts may be intraosseous, staying inside of the bone marrow. Or they may be extraosseous, developing on the surface of the bone, and extending into the marrow.

Phases

  1. Initial phase of osteolysis.
  2. Active growth phase, characterized by destruction of bone tissue.
  3. Stable stage, where a formation of a bony shell and internal bony septa produce its soap bubble appearance.
  4. Healing phase where the cyst eventually heals into an irregular dense bony mass.

Anatomy

The tumor can have an occurrence anywhere that there is bone. Approximate percentages by sites are as shown:

  • Skull and mandible (4%)
  • Spine (16%)
  • Clavicle and ribs (5%)
  • Upper extremity (21%)
  • Pelvis and sacrum (12%)
  • Femur (13%)
  • Lower leg (24%)
  • Foot (3%)

Symptoms

The afflicted may have relatively small amounts of pain that will quickly increase in severity over a time period of 6-12 weeks. The skin temperature around the bone may increase, a bony swelling may be evident, and movement may be restricted in adjacent joints.

Spinal lesions may cause quadriplegia and patients with skull lesions may have headaches.

See also

Giant cell tumor of bone

External links

Wikipedia content modification information:

  • This page was last modified on 24 August 2008, at 23:50.

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