CASE 18400 Published on 01.12.2023

A rare case of a large spinal cord arachnoid cyst



Case Type

Clinical Case


Jayaranjeetham Jayabalan 1, Shweta Singh 1, Deepak Barathi S. 1, Sreerekha Jinkala 2

1 Department of Radiodiagnosis, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India

2 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India


45 years, female

Area of Interest Abdomen, Arteries / Aorta, Biliary Tract / Gallbladder ; Imaging Technique CAD, Cone beam CT, Conventional radiography
Clinical History

A 45-year-old lady presented with complaints of low back aches for 2 years and numbness of the right lower limb for 6 months. So she was advised to undergo an MRI lumbar spine, suspecting disc herniation. No history of trauma.

Imaging Findings

MRI of the spine (Figures 1 and 2) shows a well-defined large CSF signal intensity lesion noted in the dorso–lumbar region (D11 to L3 level) at the extradural space, causing compression on the spinal cord and cauda equina nerve roots. Thin T2 hypointense septation noted within. On post-contrast scan (Figures 3a and 3b), there was no obvious contrast enhancement within the lesion.


Spinal cord arachnoid cysts are uncommon. Arachnoid cysts are CSF-filled sacs lined by arachnoid mater. It can be either congenital or acquired. Extradural spinal arachnoid cyst occurs as a result of the defect in the dura, which results in accumulation of the CSF fluid and communication defects between cyst and subarachnoid space [1].

It remains undiagnosed in most of the asymptomatic patients. In symptomatic patients, compression of the cord causes spastic & flaccid paralysis, pain, weakness, numbness, bladder and bowel incontinence.

For patients who are asymptomatic or with mild symptoms, expectant management is followed [2]. Surgery is the option for the rest of the patients [3].

Here, we report a case of a large spinal extradural arachnoid cyst who presented with complaints of low back aches for 2 years. The magnetic resonance imaging (MRI) findings and postoperative findings of the spinal arachnoid cyst are discussed.

As the patient was symptomatic, the neurosurgeon planned excision of the cyst and decompression following D11L2 laminectomy. Post-surgery, the symptoms of the patient improved. The microphotograph (Figure 4) shows a cyst wall composed of fibro-collagenous tissue lined by single layer of flattened cells H and E – suggestive of an arachnoid cyst.

It is important for radiologists to diagnose spinal cord arachnoid cysts as, most of the time, the diagnosis is an incidental finding in a symptomatic patient. Also, the diagnosis can be missed many times due to its CSF signal intensity.

All patient data has been completely anonymised throughout the entire manuscript and related files.

Differential Diagnosis List
Spinal cord herniation
Spinal cord arachnoid cyst
Dural ectasia
Final Diagnosis
Spinal cord arachnoid cyst
Case information
DOI: 10.35100/eurorad/case.18400
ISSN: 1563-4086