Single-stage craniectomy and custom titanium cranioplasty for intradiploic arachnoid cyst: illustrative case

BACKGROUND: Intradiploic arachnoid cysts (IACs) are a rare benign cause of osteolytic skull lesions. OBSERVATIONS: Here the authors describe a 60-year-old female who presented with an incidental osteolytic skull lesion involving the right parietal bone with no history of trauma. CT imaging revealed an expansile lesion with thinning of the inner and outer tables. MRI showed a CSF-isointense cystic lesion. These radiographic findings were corroborated intraoperatively. LESSONS: The optimal management of IACs is still developing; both conservative and surgical approaches have been reported. In cases in which resection is indicated, custom titanium cranioplasty may offer an effective reconstructive technique. https://thejns.org/doi/abs/10.3171/CASE25494.