CT and MRI in spinal meningeal cyst. Report of a case.

A case of meningeal cyst of the spinal canal in the lumbosacral region is described. A CT scan showed a soft tissue mass associated with bone erosion. Myelography and computerised tomographic myelography revealed a cyst filling with contrast and thus CSF containing. The diagnosis of meningeal cyst was confirmed in a non-invasive way by MRI showing a mass with the same signal intensities as CSF on both T1 and T2 weighted images. Final characterisation of meningeal cysts in one of the three categories comprising spinal extradural meningeal cyst without spinal nerve root fibers (type I), spinal extradural meningeal cyst with spinal nerve root fibers (type II) and intradural meningeal cyst (type III) is impossible without operative inspection and histological examination.