RESUMEN
Perineural cyst (Tarlov cyst) is a lesion in a form of fluid-filled sacks, usually located within the nerve root sheath at the posterior root of a spinal nerve, whose wall is formed by: endoneurium, peripheral nerve fibers and ganglion cells and areolar tissue. Depending on the studied population, the frequency of lesion occurence was estimated at 1.5- 13.2%, with its significant majority occuring in women. Cyst development may be the result of ischemia, hemorrhage, inflammation or trauma. Cysts are usually asymptomatic theefore they are likely to bo detected accidentally. However, in approximately 1/4 of the cases, the cyst puts so much pressure on the nerve and the neighbouring nerve roots that it becomes symptomatic (causes pain). The presence of clinical symptoms may be an indication for conservative treatment (i.e. analgesics, rehablitation, cyst puncture) or surgery (usually laminectomy).