Posterior extradural lumbar disk fragment

We present the unique case of a patient with a sequestered disk fragment posterior to the thecal sac producing symptoms of spinal stenosis with neurogenic claudication. The majority of sequestered disk fragments migrate in either a cranial or caudal direction. In only a few cases have disk fragments been identified posterior to the thecal sac. Our patient had a sudden onset of bilateral groin and anterior thigh pain. Magnetic resonance imaging showed relatively severe stenosis at L4-5 with mild disk bulging. Intraoperatively, a large posteriorly placed encapsulated mass of soft tissue was found compressing the posterior portion of the thecal sac. Patients with acute onset of symptoms of spinal stenosis should have herniated disk included in their differential diagnosis, even in the absence of imaging confirmation.