Optic nerve glioma mimicking an optic nerve meningioma

Optic nerve glioma mimicking an optic nerve meningioma

Clinical Neurology and Neurosurgery ELSEVIER Clinical Neurology and Neurosurgery 98 (1996) 258-261 Case report Optic nerve glioma mimicking an opt...

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Clinical Neurology and Neurosurgery

ELSEVIER

Clinical Neurology and Neurosurgery 98 (1996) 258-261

Case report

Optic nerve glioma mimicking an optic nerve meningioma L. L i a u w a,*, G . J . V i e l v o y e % R . J . W .

d e K e i z e r b, S . G . v a n D u i n e n e

aDepartment of Radiology and Nuclear Medicine (subdivision Neuroradiology), University Hospital Leiden, Albinusdreef 2, 2300 RC Leiden, Netherlands bDepartment of Ophthalmology, University Hospital Leiden, Albinusdreef 2, 2300 RC Leiden, Netherlands CDepartment of Pathology, University Hospital Leiden, Albinusdreef 2, 2300 RC Leiden, Netherlands

Received 8 January 1996; revised 26 March 1996; accepted 26 March 1996

Abstract

The case is described of an optic nerve glioma, mimicking an optic nerve meningioma in a man aged 41 years. CT, MRI and DSA revealed an enhancing tumor surrounding the optic nerve. Histopathologic examination of the removed optic nerve revealed a centrally located glioma surrounded by normal optic nerve fibres. Keywords: Optic nerve meningioma; Optic nerve glioma; Orbital tumor; Angiography

1. Introduction

Gliomas are the tumors most frequently encountered in the optic nerve [4,5]. On computer tomography (CT), gliomas have a fusiform or tubular appearance with well delineated margins [1,6-8]. Kinking or buckling of the optic nerve may occur [2,3,6-8]. Calcifications are seldom observed [9]. Characteristically, magnetic resonance imaging (MRI) T1 weighted images show a lesion with low or isosignal intensity [1,8,10,11]. On T2 weighted images, fusiform gliomas display a high-signal intensity. On the other hand, tubular gliomas have a more heterogeneous signal intensity [11]. Angiographic studies of optic nerve gliomas fail to show any pathological vascularisation [1-3,12]. On CT scans, meningiomas have a fusiform or tubular appearance and display straightening of the optic nerve [2-4]. The tumor may extend intracranially [4,5]. Calcifications due to psammoma bodies are often present [2,4]. Meningiomas enhance far more intensely than gliomas [4]. The tramtrack phenomenon [9] observed on axial scans is not pathognomonic for meningiomas, but is also seen in conditions such as neuritis or pseudotumor [13]. On coronal scans the doughnut phenomenon *Corresponding author. Tel.: +31 71 5262042; Fax: +31 71 5248256.

corresponds to the tramtrack sign [9]. Hyperostosis or sclerosis of the adjacent bony structures is often observed [9,14,15,17]. In optic nerve meningioma, MRI reveals a low-signal intensity lesion on both T1 and T2 weighted images [1,7,11]. Meningiomas may show a characteristic tumor blush when studied by angiography [1-3,15,17]; in the absence of a blush, angiography cannot differentiate between meningiomas and gliomas [15]. This case report demonstrates radiological pitfalls that may occur in the differential diagnosis between optic nerve glioma and meningioma. All radiological examinations, including CT, M R I and digital-subtraction angiography, supported the diagnosis of optic nerve meningioma. Particularly the angiographic features (tumor blush) seemed compatible with an optic nerve meningioma. Pertinent literature mentions no tumor blush in optic nerve gliomas in the capillary or venous phase of angiographic examination [1-3].

2. Case report

Four weeks before referral to our hospital, a 41-yearold white male complained of blurred vision of the left eye. Two weeks befoJ :, referral, his vision deteriorated

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L. Liauw et al. / Clinical Neurology and Neurosurgery 98 (1996) 258-261

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giography was performed with a Philips Integris 3000. The left ophthalmic artery had a normal calibre. However, there was a blush of pathological vessels at the site of the optic nerve (Fig. 3). Since visual acuity was 0 for at least 1 day, decompression of the optic nerve was not performed. There was, moreover, the risk of shedding meningioma cells. In our clinic the treatment regime in this type of lesions is surgery to prevent further intracranial extension when the meningioma has extended beyond the optic canal. In this patient with a visual acuity of 0, the optic nerve tumor was removed because of possible tumorgrowth that could compromise visual acuity of the other eye and because of patient's fear of malignancy.

Fig. 1. This axial CT image shows a tubular thickening of the left optic nerve. progressively, in particular in the lower visual field, and eye movements were painful. On initial examination elsewhere, routine CT :scan of the brain showed no abnormalities. N o CT :+can o f both orbits had been performed. His medical history included open tuberculosis at the age of 21. Physical examination did not reveal any abnormalities, particularly no signs of neurofibromatosis. Ophthalmologic examination showed a visual acuity of 0.8 of the right eye; the optic disc had a normal colour and configuratio~a, and ocular pressure was 20 mm Hg A T (normal). "['he visual acuity of the left eye was 0.6 initially, but 6eteriorated progressively to 0 within 1 month. The left optic disc was very prominent and displayed swollen veins. Ocular pressure was 13 mm Hg AT; the left eye showed minimal exotropia and hypertropia, and tl~ere was no pain or restriction of eye movements, nor e,xophthalmos, a clinical picture corresponding to pseudoneuritis. CT examination (Fig. 1) showed a tubular thickening of the left optic nerve extending from the eye bulb to the optic canal. A coronal series after intravenous contrast administration reve,aled linear enhancement of the optic nerve. Sonographic examination demonstrated a thickening of the optic nerve and nerve sheath. MRI was performed using st Philips Gyroscan S15 (field strength 1.5 T). T1 weighted images (TR 600 ms, TE 20 ms) showed thickening of the left optic nerve with an intermediate-signal intensity (Fig. 2A). On gadolinium administration, a tramline-like enhancement was observed at the periphery of the optic nerve (Fig. 2). The chiasm was not affected. T2 weighted images were not performed. The combined results of these examinations made a diagnosis of a meningioma of the left optic nerve highly probable. Digital-subtraction an-

B

Fig. 2. A: thickening of the left optic nerve with an intermediatesignal intensity (coronal T1 weighted (550/22) SE MR image). B: peripheral enhancement of the optic nerve after intravenous administration of gadolinium (axial T2 weighted (600/20) SE MR image).

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L. Liauw et aL I Clinical Neurology and Neurosurgery 98 (1996) 258-261

Fig. 3. A: selective catheterization of the left internal carotid artery displays a normal calibre left ophthalmic artery. B: higher magnification of the left ophthalmic artery shows a blush of pathological vessels. One month later, the tumor including the optic nerve was removed en bloc via superior transcranial route. Histopathologic examination of the enlarged optic nerve showed abnormal tissue in the centre of the nerve, surrounded by a rim of normal nerve fibre bundles. The pia, arachnoidea, and dura displayed no abnormalities (Fig. 4A). At a higher magnification (Fig. 4B), the abnormal tissue consisted of elongated, glial fibrillary acid protein positive (GFAP), and Leu-7-positive astrocytic cells, which tended to cluster, especially around capillaries. The neoplastic astrocytes had a fibrillary cytoplasm and a predominantly oval nucleus with slight polymorphism. N o mitosis or necrosis was observed. The tissue showed mucinous changes in the centre of the t u m o r and the presence of some Rosenthal fibres. Within the tumor the wall of most capillaries

Fig. 4. A: cross section of optic nerve with centrally located glioma tissue (top), surrounded by apparently normal nerve fibre bundles and intact pia and dura (H and E, X40). B: higher magnification of the glioma. Note the prominent vascular proliferation (H and E, x 200).

L. Liauw et al. /Clinical Neurology and Neurosurgery 98 (1996) 258-261

showed marked proliferation. Between the tumor-cells, degenerating axons and myelin sheaths were observed. At follow-up examination 1 month after surgery, the patient's left eye showed minimal ptosis and exotropia. Gliotic tissue surrounded the optic disc. Four months postoperatively, the eye movements of the left eye were normal. No abnormalities were observed clinically and with MRI examination no tumor residue was revealed.

3. Discussion In most cases computer tomography and MRI can differentiate between gliomas and meningiomas of the optic nerve. Differentiation can be very difficult, particularly in the case of a diffusely and narrow expanded optic nerve [2,16]. As a third radiological means for differentiation digital-subtraction angiography can be used. According to the literature [1-3,15] abnormal vessels, including tumor blush, are highly suspect for a meningioma. A normal angiogram does not exclude the presence of a meningioma. In this patient, radiological examination indicated an optic nerve meningioma. On CT scans, the circumference of the optic nerve clearly enhanced following the administration of contrast medium. This phenomenon is reported to be pathognomonic for a meningioma. Moreover, the results of MRI examination of the orbit supported this diagnosis. Unfortunately, no T2 weighted images were performed. High-resolution digital subtraction angiography revealed a tramline-like tumoral vessel complex, fed by the ophthalmic artery, surrounding the optic', nerve. Thus, angiography strongly supported the diagnosis of an optic nerve meningioma. Contrary to our expectations, the histological findings showed an optic nerve glioma. In the centrally located tumor hypertrophy and hyperplasia of the vessel walls was observed as seen usually in higher grade gliomas. These vessels are invisible with sophisticated angiography. The perifi~ral enhancement on CT and MRI, and the blush seen with angiography suggests hypervascularity, probably reactive, due to the presence of tumor centrally.

Acknowledgments We thank R.T.W.M. Thomeer, MD, Department of Neurosurgery, University Hospital Leiden, for his comments.

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