Aneurysmal bone cyst T11

Case contributed by RMH Neuropathology


Worsening radiculopathy and back pain with 1/52 of incontinence.

Patient Data

Age: 27
Gender: Male

Normal vertebral alignment. There is a 20 mm x 37 mm x 35 mm lytic expansile lesion centered within the right posterior elements of T11 thoracic vertebra extending into the spinous and right transverse process. There is marked cortical thinning, with cortical breaches, but no evidence of calcification or internal matrix. Zone of transition appears narrow.

As a result of the expansion, there is marked narrowing of the spinal canal at this level, as well as narrowing of the T11-T12 exit foramen on the right. There is also a small lytic lesion in the right posterosuperior pedicle of T12 with cortical thinning against the spinal canal; this abuts & is most probably extension of the T11 tumor.


Lytic expansile lesion centered within the posterior elements of T11 on the right causing significant spinal canal stenosis and likely cord compression.


The posterior elements of T11 are expanded by a mass with peripheral and septal enhancement and multiple fluid fluid levels. 


Brown tan bony and fibrous tissue 75x45x5mm.


The sections show blood-filled cyst like spaces which are arranged haphazardly within a moderately cellular stroma. Stromal cells have both spindle and epithelioid morphology and show mild nuclear pleomorphism. These are admixed with a large number of osteoclast-like multinucleated cells. Scattered mitotic figures are noted. No necrosis is seen. Irregularly shaped fragments of woven bone are present within the lesion and there is re-modelling of trabeculae of lamellar bone at the periphery of the lesion. No malignant osteoid is identified. The features are of aneurysmal bone cyst.

DIAGNOSIS: Aneurysmal bone cyst.

Case Discussion

Lesions originating in posterior elements of the vertebrae includes

  • metastases
  • pedicle reactive sclerosis
  • osteoid osteoma
  • aneurysmal bone cyst
  • osteoblastoma
  • hypoplastic /aplastic pedicle
  • spondylolysis

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