Synovial cysts of the lumbar facet joint.

A study of 42 synovial cysts arising from the lumbar facet joint is presented. Intraspinal cysts caused radicular pain and cauda equina syndrome in 11 patients. In a series of 1,400 lumbar laminotomies for a herniated disk, 31 incidental nodules arising from the exposed facet as paraarticular masses were found and excised. The limited number of reports in the orthopedic and neurosurgical literature has not dealt adequately with the etiology or incidence of these benign lesions. The neuroradiologic appearance and histopathologic findings are briefly discussed.