Rare thoracic arachnoid cyst following costovertebral tumor resection.

Background: Spinal arachnoid cysts are rare and pose a substantial clinical challenge due to their varied etiologies, ranging from acquired (i.e., including iatrogenic) to congenital. They most frequently involve the thoracic spine, where the spinal canal is the narrowest, heightening the risk of significant cord compression/myelopathy. Case Description: Following resection of a thoracic costovertebral tumor, a 55-year-old female developed a symptomatic thoracic arachnoid cyst. After the dural defect was repaired, the patient's symptoms resolved. Conclusion: This article highlights the risk of developing symptomatic post-operative iatrogenic thoracic arachnoid cysts following the resection of thoracic tumors. Once the dural defect is repaired, lesions typically do not recur, and patients remain asymptomatic.