Endodermal and Arachnoid Cysts: Lessons From a Challenging Case.

Spinal intradural ventral cysts are rare. This article reports a rare case of the coexistence of arachnoid and endodermal cysts in the cervical spine. A 34-year-old man presented with left upper limb pain and thermal hypoalgesia in the right hand that began four years earlier, progressing to additional pain and numbness in the left arm. He also exhibited weakness in the left extremities and disturbances in fine hand movements. Magnetic resonance imaging (MRI) revealed two intradural extramedullary cysts at the C3/4 spinal level compressing the spinal cord from the left ventral side. Surgery, involving C3-5 laminoplasty and cyst excision, was performed with an exoscope and endoscope, resulting in improved symptoms and MRI-confirmed cyst removal. Histopathological examination identified the cyst as an arachnoid cyst. However, six months after the operation, his left arm pain recurred, and MRI indicated cyst recurrence. A second surgery with C3-4 corpectomy, cyst removal, and C3-5 anterior cervical fixation was performed. Histopathologically, an endodermal cyst was diagnosed based on epithelial characteristics. Following surgery, the patient's symptoms improved, and the MRI showed no cyst recurrence for three years. This case underscores the diagnostic complexities of distinguishing between arachnoid and endodermal cysts and highlights the importance of adaptable surgical strategies, including posterior and anterior approaches, for the effective management of recurrent ventral cysts. The findings emphasize the need for multidisciplinary care and long-term follow-up to achieve favorable patient outcomes.