MR Imaging of Migrated Nucleus Pulposus after Collagenase Injection of Lumbar Disc Herniation: A Case Report.

Magnetic resonance images (MRI) of migrated nucleus pulposus after collagenase treatment of lumbar disc herniation are rarely published. Here, we describe a 65-year-old woman with L5-S1 intervertebral disc herniation on the rear left. The patient was treated with a lumbar disc collagenase injection, and the pain was relieved. Two weeks later, the patient suddenly developed pain again after engaging in weight-bearing activity. Lumbar MRI showed a nodule in the spinal canal at the L5-S1 level. The patient underwent surgical treatment two days later. Pathology showed that the nodule was nucleus pulposus tissue. It is important to understanding the MR manifestations of migrated nucleus pulposus after collagenase treatment to prevent such misdiagnosis.