en Gamma Knife Radiosurgery Case report <p style="text-align: justify;"><strong>Background & Importance:</strong> Disc herniation is defined as the prolapsed of material disc into the spinal canal. If the disc fragment is free&nbsp;in spinal canal, it is called sequestration disc fragment. Occasionally, alteration in sequestration disc fragment makes the diagnosis of the&nbsp;disc herniation, challenging.<br> <strong>Case Presentation:</strong> We reviewed a rare case of the cervical sequestrated disc herniation mimicking a spinal canal extradural abscess.&nbsp;The 55-year-old man presented cervical axial and radicular pain. Cervical spine MRI showed an extra-axial longitudinal mass behind C5&nbsp;and C6 vertebral body association with anterior compression on cord. In T2 images of lesion, the signal intensity varied from isointense&nbsp;to hyperintense and marked peripheral enhancement with GD injection. After unilateral right C6 hemilaminectomy, a sequestrated disc&nbsp;fragment was resected from epidural space.<br> <strong>Conclusion:</strong> The histopathologic findings were in favor of sequestrated disc herniation. Although MRI is the main preoperative diagnostic&nbsp;tool for accurate diagnosis of the sequestrated disc herniation, the sequestrated disc fragment can show the variable features on MRI and&nbsp;can be misdiagnosed with the other space-occupying lesions.</p> Cervical Disc Herniation, Sequestrated Disc Fragment, Mass Lesion 24 29 http://irjns.org/browse.php?a_code=A-10-39-1&slc_lang=en&sid=1 Ali Babashahi علی باباشاهی 10031947532846003127 10031947532846003127 No MD, Assistant Professor of Neurosurgery, Iran University of Medical Sciences, Rasool-e Akram Hospital, Tehran, Iran Morteza Taheri مرتضی طاهری 10031947532846003128 10031947532846003128 Yes MD, Resident of Neurosurgery, Iran University of Medical Sciences, Rasool-e Akram Hospital, Tehran, Iran