Lumbar interdural meningioma: A case report and anatomical considerations

Abstract

Background:

Interdural spinal meningiomas, arising between dural layers, are exceptionally rare.

Case Description:

A 50-year-old male presented with a 2-month history of lower back pain and numbness in the left L2-L3 dermatome. The magnetic resonance imaging (MRI) demonstrated a 25 × 14 × 8 mm, well-circumscribed, extradural-appearing mass at L2 with extension into the left L2/3 foramen. The lesion was hypointense on the T2WI and T2 heterogeneously enhanced with gadolinium. The preoperative differential diagnosis included schwannoma and extradural meningioma. At surgery, the lesion was entirely interdural. Complete resection was achieved with preservation of the inner dural layer. Histopathological examination confirmed a metaplastic meningioma with extensive chondroid metaplasia. The patient’s symptoms resolved completely, and at 7 postoperative months, the MRI showed no recurrence.

Conclusion:

Here, we report an interdural L2-L3 meningioma that was completely resected while preserving the inner dural layer.

INTRODUCTION

Spinal meningiomas are typically intradural extramedullary, whereas interdural lesions are extraordinarily uncommon.[4,5] Here, we report a L2-L3 lumbar interdural meningioma with histological evidence of extensive chondroid metaplasia.

CASE DESCRIPTION

A 50-year-old male presented with 2-months of lower back pain and numbness over the left anterior thigh L2-L3 dermatome, but no motor deficit. The magnetic resonance imaging (MRI) demonstrated a well-circumscribed L2 mass measuring 25 × 14 × 8 mm, extending into the left L2/3 foramen [Figure 1]. It appeared extradural and was isointense on T1-weighted imaging, predominantly hypointense on T2-weighted imaging, and showed heterogeneous gadolinium enhancement. The computed tomography documented no bone destruction [Figure 1]. The preoperative differential diagnosis included schwannoma and extradural meningioma.

Figure 1:

Preoperative lumbar imaging: (a) sagittal T1, (b) sagittal T2, (c) sagittal short tau inversion recovery, (d) sagittal gadolinium-enhanced T1, (e) axial T2, (f) axial gadolinium-enhanced T1, (g) coronal gadolinium-enhanced T1 magnetic resonance imaging, (h) radiograph, and (i) computed tomography of the L2 tumour with left L2/3 foraminal extension.

Surgery

After a L2 laminoplasty was performed, and once the outer dural layer was opened, a yellow-white granular totally interdural tumor was exposed [Figure 2]. The lesion was totally removed, while preserving the inner dural layer (i.e., Simpson Grade 2 resection).

Figure 2:

Intraoperative photographs. (a) No intradural mass lesion was identified. (b) Epidural vascular proliferation was observed. (c and d) A yellowish-white granular mass protruded after incision of the outer dural layer. (e) Dural closure was performed using VCS clips. VCS : Vessel closure system.

Pathology

The histopathological examination demonstrated a metaplastic meningioma with extensive chondroid metaplasia (i.e., World Health Organization Central NERVOUS SYSTEM Grade 1) [Figure 3].[3] Postoperatively, the patient’s lower back pain and numbness resolved completely. The MRI 7 months later confirmed complete tumor resection without recurrence.

Figure 3:

Histopathological findings of the tumour. Hematoxylin and eosin staining showed spindle cell proliferation in a background of cartilaginous tissue and fibrous stroma (original magnification ×40).

DISCUSSION

Interdural spinal meningiomas are exceptionally rare, with few cases, in addition to this one, reported in the literature [Table 1]. The present case indicates that a meningioma can arise within the interdural substance, progressively separating the inner from the outer dural layers [Figure 4].[6] In this case, the mass had a lobulated contour and appeared to envelop adjacent neural structures [Figure 1]. Gross total removal was achieved, but the inner dural layer was preserved and coagulated rather than resected (i.e., Simpson Grade 2 removal). Because management of the dural attachment in spinal meningiomas remains debated and late recurrence is well recognized, long-term MRI follow-up is advised.[1,2]

Table 1:

Summary of reported interdural spinal meningioma cases.

Figure 4:

Schematic illustration of the presumed tumour location within the laminar structure of the spinal dura, creating a split-dura interdural compartment, in contrast to a conventional extradural tumour.

CONCLUSION

A 50-year-old male presented with an interdural spinal meningioma at the L2-L3 level that was totally excised, while preserving the inner dural layer.

Ethical approval:

Institutional review board approval is not required.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their images and other clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-Assisted Technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.