Extra-foraminal Intraneural L5-S1 Disc Herniation Mimicking a Retroperitoneal Peripheral Nerve Sheath Tumour: Case Report and Review of the Literature

Upper lumbar spine far lateral disc herniations masquerading as peripheral nerve sheath tumors: illustrative cases

BACKGROUND

Migratory disc herniations can mimic neoplasms clinically and on imaging. Far lateral lumbar disc herniations usually compress the exiting nerve root and can be challenging to distinguish from a nerve sheath tumor due to the proximity of the nerve and characteristics on magnetic resonance imaging (MRI). These lesions can occasionally present in the upper lumbar spine region at the L1-2 and L2-3 levels.

OBSERVATIONS

The authors describe 2 extraforaminal lesions in the far lateral space at the L1-2 and L2-3 levels, respectively. On MRI, both lesions tracked along the corresponding exiting nerve roots with avid postcontrast rim enhancement and edema in the adjacent muscle tissue. Thus, they were initially concerning for peripheral nerve sheath tumors. One patient underwent fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) screening and demonstrated moderate FDG uptake on PET-CT scan. In both cases, intraoperative and postoperative pathology revealed fibrocartilage disc fragments.

LESSONS

Differential diagnosis for lumbar far lateral lesions that are peripherally enhancing on MRI should include migratory disc herniation, regardless of the level of the disc herniations. Accurate preoperative diagnosis can aid in decision making for management, surgical approach, and resection.

Lumbar disc sequestration mimicking a tumor: Report of four cases and a literature review

BACKGROUND

Disc herniation refers to the displacement of disc material beyond its anatomical space. Disc sequestration is defined as migration of the herniated disc fragment into the epidural space, completely separating it from the parent disc. The fragment can move in upward, inferior, and lateral directions, which often causes low back pain and discomfort, abnormal sensation, and movement of lower limbs. The free disc fragments detached from the parent disc often mimic spinal tumors. Tumor like lumbar disc herniation can cause clinical symptoms similar to spinal tumors, such as lumbar soreness, pain, numbness and weakness of lower limbs, radiation pain of lower limbs, etc. It is usually necessary to diagnose the disease according to the doctor's clinical experience, and make preliminary diagnosis and differential diagnosis with the help of magnetic resonance imaging (MRI) and contrast-enhanced MRI. However, pathological examination is the gold standard that distinguishes tumoral from non-tumoral status. We report four cases of disc herniation mimicking a tumor, and all the pathological results were intervertebral disc tissue.

CASE SUMMARY

The first case was a 71-year-old man with low back pain accompanied by left lower extremity radiating pain for 1 year, with exacerbation over the last 2 wk. After admission, MRI revealed a circular T2-hypointense lesion in the spinal canal of the L4 vertebral segment, with enhancement on contrast-enhanced MRI suggesting neurilemmoma. The second case was a 74-year-old man with pain in both knees associated with movement limitation for 3 years, with exacerbation over the last 3 mo. MRI revealed an oval T2-hyperintense lesion in the spinal canal at the L4–5 level, with obvious peripheral enhancement on contrast-enhanced MRI. Thus, neurilemmoma was suspected. The third case was a 53-year-old man who presented with numbness and weakness of the lumbar spine and right lower extremity for 2 wk. MRI revealed a round T2-hyperintense lesion in the spinal canal at the L4–5 level, with obvious rim enhancement on contrast-enhanced MRI. Thus, a spinal tumor was suspected. The fourth case was a 75-year-old man with right lower extremity pain for 2 wk, with exacerbation over the last week. MRI revealed a round T1-isointense lesion in the spinal canal of the L3 vertebral segment and a T2-hyperintense signal from the lesion. There was no obvious enhancement on contrast-enhanced MRI, so a spinal tumor was suspected. All four patients underwent surgery and recovered to ASIA grade E on postoperative days 5, 8, 8, and 6, respectively. All patients had an uneventful postoperative course and fully recovered within 3 mo.

CONCLUSION

Disc herniation mimicking a tumor is a relatively rare clinical entity and can be easily misdiagnosed as a spinal tumor. Examinations and tests should be improved preoperatively. Patients should undergo comprehensive preoperative evaluations, and the lesions should be removed surgically and confirmed by pathological diagnosis.