MRI
The MRI study better depicts the cystic nature of the sacral lesion. The lesion is bubbly-looking with multiple septations and fluid-fluid levels. It is arising from the posterior element of the sacral spine extending from S1 to S5 with mild extension to the body of S2 and S3 through the bilateral pedicles. There is significant narrowing at the distal sacral spinal canal, however, there is no compromise on the neural foramina. Minimal septal enhancement is seen in the post contrast images.
The MRI features are highly suggestive of aneurysmal bone cyst.