title: Transition of a herniated lumbar disc to lumbar discal cyst: A case report.
abstract: BACKGROUND
  Another rare cause of lower back pain with radiculopathy is the discal cyst. It is believed to arise from degeneration of a herniated disc, although many other theories of its origin have been proposed. Here, we report a patient with lower back pain/radiculopathy attributed originally to a herniated lumbar disc, which transformed within 6 months into a discal cyst.
  
  
  METHODS
  A 42-year-old male had a magnetic resonance (MR) documented herniated lumbar disc at the L4-5 level. It was managed conservatively for 6 months, after which symptoms recurred and progressed. The follow-up MR study revealed a discal cyst at the L4-5 without residual herniated disc. Of interest, the cyst communicated with the L4-5 intervertebral disc, which was herniated under the posterior longitudinal ligament and the disc space. During surgery, the cyst was completely removed, and his symptoms/signs resolved.
  
  
  CONCLUSIONS
  A discal cyst develops as pathological sequelae of a degenerated herniated disc. Although rare, these lesions must be considered among the differential diagnoses in young patients with radicular back pain. MR study clearly documents these lesions, and surgical excision of the cyst is the treatment of choice.
authors.affiliation: Spine Section, Department of Neurosurgery, Southern Tohoku Research Institute for Neurosciences, Koriyama, Japan.
authors.forename: Rohit
authors.initials: R
authors.lastname: Bansil
authors.affiliation: Spine Section, Department of Neurosurgery, Southern Tohoku Research Institute for Neurosciences, Koriyama, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hirano
authors.affiliation: Department of Pathology, Southern Tohoku Research Institute for Neurosciences, Koriyama, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Sakuma
authors.affiliation: Spine Section, Department of Neurosurgery, Southern Tohoku Research Institute for Neurosciences, Koriyama, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Watanabe
keywords: Degeneration; discal cyst; intervertebral disc; lumbar; pathogenesis