Diagnostic Dilemma in Discriminating Between Spinal Neurenteric Cysts and Simple Arachnoid Cysts Based on Embryogenesis and Surgical Correlation

Background: Neurenteric cyst (NEC) is a rare intradural spinal tumor, but a correct preoperative diagnosis remains challenging. A misdiagnosis of arachnoid cyst (AC) often leads to conflicting surgical management and significantly higher recurrence. Case Description: We report the case of a 26-year-old woman who presented with progressive spastic quadriparesis with myelopathy below the C4 level, which was caused by a ventral intradural extramedullary cystic tumor at the C3-4 level. Magnetic resonance images showed the cystic content as identical to cerebrospinal fluid, which prompted the tentative diagnosis of spinal AC. Surgical fenestration was scheduled. However, intraoperative findings of a thick-walled cyst and severe adhesion to the neural structure without a history of trauma and inflammation were more compatible with the pathogenesis of an NEC. Because of the high recurrence rate after an incomplete resection of an NEC, we did a complete resection of the cyst with adhesive rootlets instead. Pathology analysis and immunohistochemical staining confirmed the diagnosis of an endodermal-derived NEC. Conclusions: NECs must be differentiated from ACs because they are different diseases and require different surgical management. In cases with clear cystic content, however, the diagnosis is likely to be AC, but a thick cystic wall and structural adhesions should suggest the differential diagnosis of NEC. Gross total removal of NECs should be attempted to reduce NEC recurrence.