Non-traumatic intraosseous cerebrospinal fluid cyst with associated craniovertebral anomalies: a case report and suggested mechanism of formation.

Intraosseous cerebrospinal fluid (CSF) cysts, also known as intra-diploic arachnoid cysts, are usually of post-traumatic origin. Lesions presenting without a history of trauma are rare and are presumed to be of congenital origin. We report a young man with an intraosseous cystic lesion containing CSF and communicating with the intracranial subarachnoid space through a dural opening. The presence of other congenital defects of the skull and spine could be a pointer in this direction. Surgical management involves craniectomy and repair of the dural defect followed by cranioplasty for the bony defect.