Gas-containing "ganglion" cyst of lumbar posterior longitudinal ligament at L3. Case report.

A case of "ganglion" cyst was found to originate from the L3 lumbar posterior longitudinal ligament at the pedicular level. The patient had moderate lumbar degenerative scoliosis. The cyst had no connection with the intervertebral disc, dural sac, facet joint or nerve root. Instead of mucous or myxoid material, it contained gas. Pathology showed a thick collagenous fibrous wall with no particular linings. No synovial component could be found by immunohistochemical stains. Pathologic findings including hemosiderin deposition, chronic inflammatory cell infiltration, and calcified spots supported a chronic process of cystic degeneration of the ligament.