Chronic suppurative inflammatory cyst in the sacrum.

Sacral bone remodeling with abnormal dilatation of intervertebral foramina is usually associated with Tarlov's perineurial cysts but can also be caused by slow-growth lesions. In this case report, an atypical inflammatory sacral cyst with bone scalloping was found and some possible causes are suggested. A 77-year-old woman complained of severe back pain and claudication with anal tone weakness. A plain roentgenogram and CT showed spinal canal expansion and characteristic border scalloping of the sacrum. MRI showed septated cystic content with peripheral enhancement. Laminectomy was performed. The cyst contained yellowish viscous material that was easily removed. The neurological symptoms improved after surgery. The cystic wall was composed of dense fibrous tissue without epithelial cell lining; the cystic content was, on histology, inflammatory cells including neutrophils and lymphocytes. Patients who have sacral intraspinal cysts should be identified before doing the treatment such as acupuncture and epidural steroid injection to avoid infection to those cysts.