CASE 16791 Published on 22.06.2020
0

Optic nerve sheath meningioma (ONSM)

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Nerea Alberdi, Paul Lopez, Ana Azagra, Loreto De Llano

Radiology department; Complejo Hospitalario de Navarra, Spain.

Connected authors
Patient

43 years, female

Categories
Area of Interest Eyes, Head and neck ; Imaging Technique CT, MR
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Clinical History

43 years-old woman with hyperthyroidism and long data of exopthalmus. The woman presents progressive visual loss in the left eye and proptosis, without diplopia or eye movements’ limitation. A CT is performed.

Imaging Findings

The CT shows an isoattenuated intraconal orbital mass surrounding the left optic nerve with punctuate calcification (Fig. 1a). Following administration of contrast the mass has homogeneous enhancement (Fig. 1b), surrounding the non-enhancing optic nerve, results “tram-track sign” (Fig. 1b, arrow) on axial images or “dot sign” on coronal (Fig. 1c). Bone window (Fig. 1d) does not reveal hyperostosis of the adjacent bone or other pathological findings.

MRI is better to delineate posterior extension.  T1 weighted sequence shows an isointense to hypointense mass compared to the optic nerve (Fig. 2a), T2 weighted image shows isointense to somewhat hyperintense compared to the optic nerve (Fig. 2b). Fat –supressed T2 shows a hyperintense mass with “perioptic cysts” (Fig. 2c arrow). Diffusion weighted image shows a moderate diffusion restriction (Fig. 2d). On fat-supressed T1 and after contrast administration, the mass has homogeneous enhancement (Fig. 3a, 3b, 3c) and we can see an extension of the mass through the optic canal (Fig. 3b, arrow).

Discussion

Primary orbital meningioma is a rare tumour of the anterior visual pathway and constitutes approximately 2% of all orbital tumours and 1-2% of all meningiomas. The differentiation from secondary orbital meningioma of intracranial origin is sometimes difficult on image, but there are some keys imaging findings to suspect them (1).

Optic nerve sheath meningioma (ONSM) is typically unilateral but can be bilateral, particularly in the setting of type II neurofibromatosis (2).

 

The typical clinical presentation is painless, gradual vision loss and proptosis in a woman between ages 30 and 50 (3).

Radiology is essential for a differential diagnosis of the intraconal orbital mass and to determine the extent and tissue involved.

The key imaging finding of ONSM is a homogeneously enhancing mass that surrounds the optic nerve. MR is preferred imaging modality for tumor assessment, but CT is useful for looking for calcifications. CT images show a mass with uniform and moderately enhancement and punctate calcifications (4). “Tram track sign” is characteristic of ONSM. It refers to the parallel thickening and enhancement around the optic nerve, but is not pathognomonic because pseudotumor, lymphoma or sarcoid may show this feature (5). However, this sign is essential for the differential diagnosis with optic pathway glioma which enlarged optic nerve (Fig.4a, b, c)

Tumour extending into the optic canal may lead to canal widening, or alternatively hyperostosis or erosion of the adjacent bone (6).

 MRI is preferred imaging modality for tumour assessment and defining better the involve of orbital apex, optic canal and intracranial structures. T1 weighted images show an isointense mass to other soft tissue. T2- weighted images show a hyperintense mass with “perioptic cysts”,as in the case on point. This feature is specific and is defined as CSF increase within nerve sheath surrounding distal optic nerve between tumor and globel (7,8). This sign is not seen in other entities such as lymphoma (Fig.5a,b, c,d,e,f,g) or sarcoidosis. ADC value could be useful to distinguish meningioma from benign processes where the ADC value is higher. Nevertheless, in other entities such as lymphoma, there is an overlap in the ADC value of ONSM and lymphoma, so it is not useful for differentiate these pathologies. ONSM often shows restricted diffusion because their hypercellular nature, as well as lymphoma (9, 10). T1 weighted sequence after contrast shows homogeneous enhancement of the mass and is useful for delineating the extent of the tumour and for evaluating for intracranial extension.

 

Treatment of these lesions depends on the degree of visual impairment and proptosis. In patients with preserved vision and no proptosis, conservative management with frequent ophthalmologic and radiological follow up is usually preferred.

Fractionates stereotactic radiotherapy is considered the first line therapy for patients with preservable vision but progressive impairment (11). When the patient has severe proptosis or evidence of posterior growth, surgery is required, but almost invariably results in loss of vision (12).

 

Although rare, ONSM is the second-most common primary optic nerve tumour and could cause vision loss so early diagnosis is important.

Differential Diagnosis List
Optic nerve sheath meningioma
Optic nerve glioma
Idiopathic inflammatory pseudotumor
Metastases: most common breast and lung.
Hemangioma
Lymphoma
Final Diagnosis
Optic nerve sheath meningioma
Case information
URL: https://eurorad.org/case/16791
DOI: 10.35100/eurorad/case.16791
ISSN: 1563-4086
License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
The CT without contrast (Fig. 1a) shows an isoattenuated orbital mass with a punctate calcification. After the administration of contrast the mass has homogeneous enhancement and we can see the “track tram sign” on axial images (Fig. 1b, arrow). The “dot sign” is shown on coronal images (Fig. 1c). There is no findings in bone window (Fig. 1d).
Figure 2

T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
T1 weighted image shows an isointense to the optic nerve (Fig. 2a). T2 weighted image shows an hyperintense mass to the optic nerve (Fig. 2b). Fat –supressed T2 reveals a hyperintense mass with “perioptic cysts”.The diffusion weighted image shows moderate diffusion restriction. (Figure 2d).
Figure 3

Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Fat suppressed T1 image (Fig. 3a). Post-contrast, T1-weighted MR image (Fig. 3b, 3c) reveals an enhancing mass surrounding the optic nerve. On the axial image the posterior extension of the tumor is seen through the optic canal (Fig.3b, arrow).
Figure 4

A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a
A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a MRI. T2 weighted image (Fig. 4a) shows an enlargement and hyperintense of the optic canal. Fat suppressed T1 image (Fig. 4b). Post-contrast, T1-weighted MR image (Fig. 4c) reveals an enhancement of optic pathway. These findings are specifics of glioma of the optic pathway.
A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a
A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a MRI. T2 weighted image (Fig. 4a) shows an enlargement and hyperintense of the optic canal. Fat suppressed T1 image (Fig. 4b). Post-contrast, T1-weighted MR image (Fig. 4c) reveals an enhancement of optic pathway. These findings are specifics of glioma of the optic pathway.
A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a
A 16 years old boy with neurofibromatosis type I with loss vision in left eye comes to the ophthalmologist who recommends a MRI. T2 weighted image (Fig. 4a) shows an enlargement and hyperintense of the optic canal. Fat suppressed T1 image (Fig. 4b). Post-contrast, T1-weighted MR image (Fig. 4c) reveals an enhancement of optic pathway. These findings are specifics of glioma of the optic pathway.
Figure 5

A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows
A 86 years old man comes to the emergency department with exophthalmos and diplopia. The CT without contrast (Fig. 5a) shows an homogeneous and isodense right orbital mass. The T2 weighted image (Fig.5b) shows an isointense mass to muscle with optic nerve respected. Increased signal intensity is shown in DWI (Fig. 5c) with reduced values in ADC (Fig.5d). Fat suppressed T1 image (Fig. 5e). Post-contrast, T1-weighted MR image (Fig. 5f and fig. 5g) reveals an homogeneous enhancement of the mass with involvement of the muscles (+) and the adjacent conjunctiva (). These findings are compatible with orbital lymphoma.