Misdiagnosis of posterior sequestered lumbar disc herniation: report of three cases and review of the literature.

INTRODUCTION: Posterior migration of sequestered disc is an extremely rare event that mimics more common spinal lesions as spinal tumors, making difficult its preoperative diagnosis and appropriate management. We retrospectively reviewed all lumbar disc herniations treated by surgery at our institution from 2006 to 2016 to identify cases with posterior sequestered disc fragments and possible misdiagnosis for other spinal lesions. Complementarily, a literature review of misdiagnosed cases of posterior migrated discs was undertaken. CASE REPORT: Three posterior sequestered lumbar disc cases (one intradural), were found among the 1153 reviewed surgeries. Two of them, presenting with progressive neurological deficit, were respectively misdiagnosed as pseudotumoral lesion and meningioma/neurogenic tumor on MRI. After intraoperative diagnosis and emergent resection, histology confirmed intervertebral disc tissue. The remaining case had an accurate preoperative diagnosis and after an initial conservative management finally underwent surgery because of refractory pain. Full recovery was achieved months after surgical treatment in all cases. DISCUSSION: Non-tumoral lesions are the most frequent misdiagnosis of posterior sequestered lumbar disc described in the literature. Early surgical treatment is the standard management due to high incidence of cauda equine syndrome (CES); however, spontaneous regression of posterior sequestered lumbar disc herniations has been recently reported. In conclusion low incidence and similar clinical and radiological features with other more common posterior spinal lesions like hematomas, synovial cyst or abscess turns posterior sequestered disc herniations a diagnosis challenge. Despite high incidence of CES, an initial conservative management should be evaluated in selected patients without neurological deficit and well-controlled pain.