Spinal Extradural Meningeal Cyst: Correct Radiological and Histopathological Diagnosis

Kimiaki Sato, MD, Kensei Nagata, MD, Yasuo Sugita, MD

Disclosures

Neurosurg Focus. 2002;13(4) 

In This Article

Illustrative Cases

Case 1

This 14-year-old boy presented with a 2-week history of low-back pain. There was no history of illness or trauma. Sensory, bowel, and bladder functions were normal. Upper motor neuron dysfunction was not demonstrated. Routine laboratory tests yielded normal results. Magnetic resonance imaging demonstrated an extradural cystic lesion, with a CSF signal intensity, extending from T-12 to L-1 (Fig. 1 left). The cyst displaced the thecal sac and spinal cord anteriorly. Postmyelography CT scanning revealed that the cyst filled with contrast medium at this level (Fig. 1 right). The patient underwent a thoracolumbar laminectomy for excision of the cyst. Histopathological examination of the cyst wall showed nonspecific fibrous connective tissue. No single-cell layer of inner arachnoid lining was observed (Fig. 2).

Figure 1.

Case 1. Left: Preoperative sagittal MR image revealing an extradural meningeal cyst at T12-L1. The cyst has the same high signal intensity as the CSF on this T2-weighted sequence. Right: Axial postmyelography CT scan demonstrating that the cyst is filled with contrast medium.

Figure 2.

Case 1. Photomicrograph of the cyst wall demonstrating a fibrocollagenous layer without an inner arachnoid layer. H &E, original magnification x 25.

Case 2

This 75-year-old woman presented with a 3-year history of progressive buttock pain, left leg weakness, and urinary incontinence. Intermittent exacerbation of symptoms had occurred as had changes in posture. There was no history of illness or trauma. Routine laboratory testing yielded normal results. Magnetic resonance imaging demonstrated an extradural cystic lesion extending from S-2 to S-4 (Fig. 3). Water-soluble myelography revealed that the cyst filled with contrast medium (Fig. 4). The patient underwent a laminectomy for excision of the cyst. Histopathological examination of the cyst wall showed nonspecific fibrous connective tissue. No single-cell layer of inner arachnoid lining was observed.

Figure 3.

Case 2. Preoperative sagittal MR image revealing an extradural meningeal cyst at S2-4. The cyst has the same low signal intensity as the CSF on this T1-weighted sequence.

Figure 4.

Case 2. Water-soluble myelograms. Note the distinct fluid level of the contrast medium. Left: Anteroposterior projection. Right: Lateral projection.

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