en Gamma Knife Radiosurgery Case report <p style="text-align: justify;"><strong>Background and Importance:</strong> Disk sequestration can be defined as a herniated disk with perforation of the fibrous ring (or outermost&nbsp;annulus fibrosus) and posterior longitudinal ligament with migration of the disk fragment to the epidural space. Even after the introduction&nbsp;of high-resolution magnetic resonance imaging (MRI), it is still frequently misinterpreted as neoplastic masses. Unfortunately,&nbsp;no particular symptoms or signs are also known to allow differentiation between atypical hernias and spinal tumors.</p> <p style="text-align: justify;"><strong>Case Presentation:</strong> This study describes a rare case of a huge herniated and sequestrated disc, which is misinterpreted as a spinal tumor&nbsp;on the radiological report.</p> <p style="text-align: justify;"><strong>Conclusion:</strong> MRI findings are useful in the preoperative diagnosis of disc herniation. The differential diagnosis includes not only metastatic&nbsp;lesions but also some other benign epidural lesions such as synovial cysts, hematomas, and abscesses.</p> Disk Sequestration, Spinal Tumor, Herniated Disk 26 28 http://irjns.org/browse.php?a_code=A-10-1-5&slc_lang=en&sid=1 Guive Sharifi گیو شریفی 10031947532846003157 10031947532846003157 No Associate Professor, Shahid Beheshti University of Medical Sciences, Loghman Hakim Hospital, Tehran, Iran Ehsan Alimohammadi احسان علیمحمدی 10031947532846003158 10031947532846003158 Yes Resident of Neurosurgery, Shahid Beheshti University of Medical Sciences, Loghman Hakim Hospital, Tehran, Iran Kaveh Ebrahimzadeh کاوه ابراهیم زاده 10031947532846003159 10031947532846003159 No Assistant Professor of Neurosurgery, Shahid Beheshti University of Medical Sciences, Loghman Hakim Hospital, Tehran, Iran Karim Moradian کریم مرادیان 10031947532846003160 10031947532846003160 No Resident of Neurosurgery, Shahid Beheshti University of Medical Sciences, Loghman Hakim Hospital, Tehran, Iran Omidvar Rezaei امیدوار رضایی 10031947532846003161 10031947532846003161 No Professor of Neurosurgery, Shahid Beheshti University of Medical Sciences, Loghman Hakim Hospital, Tehran, Iran