Recurrence of a symptomatic spinal intradural arachnoid cyst 29 years after fenestration.

Symptomatic arachnoid cysts are relatively rare, and no case reports have described recurrence of such cysts almost 30 years after surgery. We herein report a case in which a symptomatic intradural arachnoid cyst recurred 29 years after fenestration of the primary lesion. The patient was a 64-year-old woman who presented with paralysis of the left lower limb. She had undergone surgical treatment for an intradural arachnoid cyst at the T12 level 29 years previously. Magnetic resonance imaging (MRI) revealed an intradural mass at the T12–L1 level. The mass was compressing the spinal cord and cauda equina. Its localization and shape on MRI were similar to those of the primary cyst 29 years previously. Partial resection was performed under a diagnosis of a recurrent intradural arachnoid cyst. After surgery, the patient’s left lower limb paralysis improved. The pathological findings were suggestive of an intradural arachnoid cyst. The MRI findings 29 years previously provided useful information. The possibility of very late recurrence should be considered in patients who undergo surgical removal of intradural arachnoid cysts.