Spinal aneurysmal bone cyst causing acute cord compression without vertebral collapse: CT and MRI findings.

Aneurysmal bone cyst (ABC) of the spine can cause acute spinal cord compression in young patients. We report the CT and MRI findings in a histology-proven case of spinal ABC presenting with sudden paraplegia. Typical features of a spinal ABC at the thoracic level with considerable extension into the posterior epidural space and cord compression were demonstrated. Special note was made of the disproportionately large longitudinal extent of the epidural component of the lesion. Associated vertebral collapse was absent. A fracture of the overlying cortex had probably allowed the lesion to decompress and track along the epidural space without significantly jeopardizing integrity of the osseous structures. This case illustrates a less frequently recognised mechanism of acute spinal cord compression by ABC.