Pediatric Aneurysmal Bone Cyst

  • Etiology: Post-traumatic or reactive in nature
  • Imaging:
    — Location: Most common location is intradmedullary in metaphysis of long bones, also seen in spine most commonly lumbar where it is usually in posterior elements destroying pedicle and where it may expand into vertebral bodies and involve more than one level
    — Lytic or blastic: Expansile lytic vascular lesion with septations and thin cortical margin that may have soft tissue component
    — Matrix: (chondroid, osteoid, fibrous)
    — Zone of transition: (wide, narrow)
    — Periosteal new bone or cortical destruction:
    — Additionally:
  • Imaging Bone scan: Increased uptake
  • Imaging MRI:
    — T2WI: Septae and fluid-fluid levels due to methemoglobin
  • DDX:
  • Complications: Can invade spinal canal and cause cord compression
  • Treatment: Surgical
  • Clinical:
    — Primary aneurysmal bone cyst seen in 10-30 years old
    — Secondary aneurysmal bone cyst seen in any age and associated with any bone lesion including primary bone malignancy

Radiology Cases of Aneurysmal Bone Cyst

CT and MRI of aneurysmal bone cyst of the spine
Sagittal (above left) and axial (above right) CT without contrast of the cervical spine shows an expansile lytic lesion with a thin margin in the spinous and transverse processes of the T1 vertebral body. There is marked anterolisthesis of T1 on T2. Sagittal T2 MRI without contrast of the cervical spine (below left) shows the anterolisthesis at T1 and T2 causing extreme cord compression while an axial T2 MRI obtained at this level (below right) shows a fluid-fluid level in the lesion to the anterior and right of the vertebral body.
CT of pediatric aneurysmal bone cyst of cervical spine
Sagittal (left), coronal (middle) and axial (right) CT without contrast of the cervical spine show a lesion in the spinous process of the C4 vertebral body that is expansile and lytic with septations and thin cortical margins.
Radiograph and MRI of aneursymal bone cyst
Lateral radiograph of the lumbar spine shows an expansile lesion in the S2 vertebral body. Axial and sagittal T2 MRI of the lumbar spine shows the S2 expansile lesion to be well defined and to have fluid-fluid levels within it.