Unusual sequestered disc fragments simulating spinal tumors and other space-occupying lesions

Object In this study the authors evaluated disease incidence, treatment, and outcome in patients with unusual sequestered disc fragments simulating spinal tumors or another space-occupying lesion on preoperative MR imaging. Methods The authors retrospectively reviewed data from the last 3000 patients with a histological diagnosis of disc herniation. Patients with preoperative MR imaging findings that simulated a spinal tumor or other spaceoccupying lesion were individually analyzed. Results In 11 patients (0.4%), MR imaging findings of unusual sequestered disc fragments were mistaken for another spinal space-occupying lesion. In 8 cases, the fragments had migrated to the posterior spinal space; in 3 cases, into the dural sac. In 3 patients, the fragments were distant from the original disc space. A heterogeneous mass was revealed with low-intensity or isointense signal on T1-weighted MR images as well as low signal (4 cases) or high signal (7 cases) intensity on T2-weighted images, relative to the spinal structures. A slight diffuse or peripheral Gd enhancement rim was observed in 7 patients. Disc fragments were located in the cervical (1 patient), thoracic (2 patients), and lumbar (8 patients) spine. All lesions were completely removed. Discectomy was required in 4 patients. A complete recovery occurred in 8 patients and a minor neurological deficit remained in 3. Conclusions Atypically located disc herniations should be considered in the differential diagnosis in patients with MR imaging data indicating spinal space-occupying disorders. All of these lesions, even those intradurally located, can be completely removed.