Postgrad Med J 1995; 71: 265-268 C) The Fellowship of Postgraduate Medicine, 1995

Diagnostic dilemmas

Neurosarcoidosis masquerading as glioma of theoptic chiasm in a child

KL Ng, N McDermott, CAJ Romanowski, A Jackson

Manchester RoyalInfirmary,Manchester, UKDepartment ofNeuroradiologyKL NgCAJ RomanowskiA JacksonDepartment ofNeurologyN McDermott

Correspondence toDr A Jackson, Department ofNeuroradiology, ManchesterRoyal Infirmary, Oxford Rd,Manchester M13 9WL, UK

Accepted 30 November 1994

SummaryWe present a case of sarcoidosis in a14-year-old girl who presented with ashort history ofvisual disturbance. Com-puted tomography and magnetic reson-ance imaging (MRI) demonstratedenlargement ofthe optic chiasm and pre-chiasmic optic nerves. Post-contrast MRIshowed marginal enhancement of theaffected areas of the optic pathways. Adiagnosis of optic nerve glioma andarachnoid gliomatosis was made; surgicalconfirmation was not sought due to therisk to vision associated with biopsy. Arapid clinical deterioration led to repeatMRI which demonstrated extensiveenhancing soft tissue throughout thebasal cisterns with extension into thebrain. Biopsy confirmed a diagnosis ofsarcoidosis.

Keywords: neurosarcoidosis, optic glioma, magneticresonance imaging

Neurosarcoidosis is a rare disease which is mostcommon in adults with evidence of systemicdisease. It may present with a diverse range ofclinical features including meningitis, cranialnerve palsies, epilepsy, hydrocephalus, andtransverse myelitis',2 (box 1). Magneticresonance imaging (MRI) and to a lesser extentcomputed tomography (CT) will demonstratesarcoidosis of the meninges and of the brainitself but are non-specific.3'4 A wide range ofradiological appearances have been describedand neurosarcoidosis may be mistaken forother diseases of the meninges (including his-tiocytosis, tuberculosis, and meningiomatosis),for diffuse white matter diseases (particularlymultiple sclerosis), or for mass lesions (such aslymphoma, glioma, or metastasis).315 The cor-rect diagnosis may be further delayed when thedisease occurs in childhood or without systemicsigns.4 We describe a case of sarcoid leptomen-ingitis in a child which clinically andradiologically masqueraded as a primaryglioma of the optic chiasm.

Case report

A 14-year-old girl who presented with a two-year history of intermittent headaches and atwo-month history of right visual disturbance.Examination revealed diminished visual acuity(4/6) and an afferent pupillary defect of the

right eye. The right optic disc was swollen andthere were fundal haemorrhages. Theremainder of the neurological examination in-cluding that of the left eye was normal. Chestradiograph, biochemical, haematological andendocrine investigations were normal.A CT brain scan demonstrated an enhancing

midline suprasellar mass in the position of theoptic chiasm. Tl-weighted MRI (SE 500/25and GE500-580/ 14/900) confirmed enlarge-ment of the optic chiasm and pre-chiasmaloptic nerves (figure 1). Following intravenouscontrast administration (Gadolinium DTPA)there was marked enhancement around theperiphery of the chiasm and pre-chiasmal opticnerves. Small areas of enhancement were alsonoted along the infundibulum, on the base ofthe hypothalamus and in the region ofthe rightlateral geniculate body (figures 2 and 3).Differential diagnoses of optic chiasm gliomaor sarcoidosis were considered, however, inview of the patient's age and the absence ofother stigmata of sarcoidosis, a diagnosis ofoptic chiasm glioma was considered most

Neurosarcoidosis

Demographic features:* age range 3 months-old age* commonest between 20 and 55 years* equal sex incidence* present in 5- 16% of systemic sarcoidosis* presenting feature in 0.3-2.5°/ of cases

Pathological features:* basal leptomeningitis* more diffuse leptomeningeal and ependymalenhancement

* intra-axial granulomatous masses* granulomatous angiitis

Clinical features:* raised intracranial pressure* hypothalamic and pituitary dysfunction* multiple cranial nerve palsies* uni- or multi-focal neurological deficits* epilepsy* stroke

Radiological features:* hydrocephalus* leptomeningeal thickening and enhancement* intra-axial mass lesions* extra-axial mass lesions* multiple high signal white matter lesions onT2-weighted MRI

Box 1

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266 Ng, McDermott, Romanowski, Jackson

likely. A biopsy was not performed due to therisk of visual deterioration and a decision wasmade to monitor the lesion using MRI unlessthe clinical condition deteriorated.Three months later, the patient developed

generalised headaches and examination dem-onstrated left-sided papilloedema. CT scanshowed marked enlargement of the suprasellarmass with obstructive hydrocephalus andbilateral ventriculo-peritoneal shunts wereinserted. Tl-weighted MRI showed a largeill-defined soft tissue mass arising in the sup-rasellar cistern and extending to involve thehypothalamus, basal ganglia, and medial tem-poral lobes (figure 4). T2-weighted images (SE2000/80) demonstrated extensive oedemaaround the mass and extending along majorfibre tracts which were involved in it (figure 5).Following contrast adminstration, diffuseenhancement of the optic chiasm, basal lepto-meninges, ependyma of the third ventricle andof the basal ganglia (figure 6) could be seen.Anteriorly, the mass was encasing the anteriorcerebral arteries, whilst posteriorly, it extended

...........

Figure 1 Sagittal T1 weighted MRI showing enlarge-ment of the optic chiasm (arrow)

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Fiur Coroal Ti-weighted.iMRI following con-

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trastshow~~~~~~~~~aingmargia. nacmn fteotccis

andurasml Saretao Tl-eptomen soingeaenhaceenrogte-baen of the hyopti halms (arrow)

i ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. __.......... us Fria.. d_I.:.:.~~~~~~~~~~~~~~.. .... . m.:.

to the lateral geniculate bodies without involve-ment of the optic radiations. A revised diag-nosis of an aggressive neoplastic or inflam-matory process was made and the most likelydiagnosis was felt to be a high grade primaryneoplasm.The patient deteriorated rapidly with

fluctuating confusion, extensive somnolenceand worsening visual acuity in both eyes. Theendocrine profile revealed inappropriateantidiuretic hormone secretion andhypogonadotrophic hypogonadism. A biopsywas therefore taken from the right intra-cranialoptic nerve and anterior optic chiasm. His-tology revealed multiple granulomata andinflammatory cell infiltrate with perivascularcuffing but no acid-fast bacilli and a diagnosisof sarcoidosis was made. The patient wascommenced on oral steroids supplemented byweekly pulses of intravenous methylpred-nisolone, in addition to demeclocycline and

pre-chiasmal~~~~~..optic nerve (sal aros.There.is also.a

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.. ..w ... ... .... . . . . ...... ... ... ....

small area of enhancem t in the-...................r....ego

Figure 3 Oblique axial T -weighted MRI followingcontrast showin genlargement of the optic chiasm andpre-chiasmal optic nerves (small arrows). There is also asmall area of enhancement in the region of the lateralgeniculate body (long arrow)

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Neurosarcoidosis masquerading as glioma of the optic chiasm in a child 267

A

Figure 5 Coronal T2-weighted images at the levels ofthe chiasm (A) and optic radiations showing extensivecerebral oedema (B, high signal) and mass effect.Extensive oedema is also seen within the optic tracts andvisual radiations (arrows)

_ _ _ _ _Figure,6 Coronal Ti-weighted M... f

trastshowing e enhancement of tb mingesandependymaof the third ventricle (arrow)

_~~~~~~~~~~~~~~~~~~~~~~~~~~~~. ... ..._ | | _~~~A

fluid restriction, with slow but progressiveimprovement of symptoms.

Discussion

Enlargement of the optic chiasm in children ismost commonly a result of optic nerve glioma.Fifty per cent of cases present before the age offive years and 90% before the age of 20. Theyare common in females and up to 25% of casesare associated with neurofibromatosis (box 2).They are extremely slow-growing glialtumours with a 40-50% 20-year survival rate.Approximately 45% originate in the chiasmand spread by direct extension along the opticpathways. They are commonly associated withprecocious puberty or other hypothalamic dis-turbance and may also cause secondary hydro-cephalus due to invasion of the ventricularsystem. Histologically there is infiltration oftheoptic pathways with glioblasts of various sizesand occasional astrocytes. Hyperplasia of theoverlying arachnoid mater, known as arachnoidgliomatosis, is a well recognised feature.'

Radiologically MRI is the optimal modalityfor investigation and demonstrates smoothenlargement of the chiasm and affected por-tions of the optic nerve. Intravenous contrastadministration results in variable degrees ofenhancement which is frequently patchy andwhich may occur on the margins of the lesiondue to arachnoid gliomatosis.7 Surgicalexcision is inappropriate since the overall prog-nosis is good and radiotherapy appears to havelittle effect on survival. Chiasmal biopsy iscontra-indicated since it has been identified asthe main cause of visual deterioration and hasalso been associated with a significant butunexplained mortality.6'8Although the incidence of neurosarcoidosis

is not documented it has been described as

Optic glioma

Demographic features:* 50% below the age of 5 years* slightly commoner in females* 15-25% associated with neurofibromatosis

Pathological features:* infiltrative tumour enlarging the optic nerve(50%), optic chiasm (45%), or optic tract(5%)

* direct spread along optic nerves, optic chiasm,and optic tracts

* tumour limited by dura* slow growth

Clinical features:* slowly progressive visual deterioration* hypothalamic and pituitary dysfunction

Radiological features:* enlargement of the affected areas of the opticpathway

* mild, usually homogeneous enhancement* rarely: peripheral enhancement due to

arachnoid gliomatosis* other features of neurofibromatosis in 5-15o°//

Box 2

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268 Ng, McDermott, Romanowski, Jackson

occurring in approximately 5- 16% of patientswith systemic sarcoid whose prevalence hasbeen estimated at 50/100 000 population.5Neurosarcoidosis is most commonly seen inpatients with systemic disease but can, rarely,be the presenting feature ofthe disease and mayremain confined to the nervous system. The ageof onset has ranged from a three month oldchild to the 8th decade but the vast majority ofcases are between the ages of 20 and 55. In thenervous system, sarcoid granulomas develop inthe leptomeninges giving rise to thickening ofthe arachnoid mater particularly around theoptic chiasm and basal cisterns but sarcoidmeningitis may occur anywhere over the sur-face of the brain or spinal cord. Granulomataare also commonly seen in the ependymallinings of the ventricles and in the choroidplexus. Parenchymal lesions may occuranywhere within the nervous system and areparticularly common in the periventricularregions and in the Virchow-Robin spaceswhere they may form granulomatous masses upto several centimetres in diameter. Sarcoidvasculitis may also occur and give rise tocerebral infarction."29

Clinically and radiologically neural sarcoid isone of the great mimics of other pathologicalprocesses. Involvement of the leptomeningesmay present with meningitic symptoms ormore classically, with multiple cranial nervepalsies.2 Intracranial lesions may cause raisedintracranial pressure, epilepsy or focalneurological deficits and sarcoid vasculitis maylead to presentation as stroke.MRI is the most useful form of radiological

investigation and intravenous contrast mediaappear to be invariably associated withenhancement in active lesions.3'4"'0 Despite thisthe MRI appearances of neurosarcoidosis areseldom distinctive. Diffuse neurosarcoidosis ismost common in the corona radiata andperiventricular regions and may be indistin-guishable from the plaques of multiplesclerosis. Solitary enhancing mass lesionswithin the neural axis are very difficult todifferentiate from lymphoma, metastatic orprimay malignant disease, while similar lesions

Learning points

* neurosarcoidosis may occur in the absence ofsystemic involvement

* neurosarcoidosis may mimic a wide range ofneurological disorders

* neurosarcoidosis has a wide range and mayoccur in childhood

* leptomeningeal enhancement on MRI shouldsuggest a diagnosis of sarcoidosis even in thepresence ofmass lesions, diffuse white matterabnormality, or focal ischaemia

Box 3

in the spinal cord may also mimic glioma,ependymoma or acute inflammatorymyelitis.1 4'5

In the present case, a leptomeningitisaffecting principally the optic chiasm and pre-chiasmal optic nerves led to an incorrect diag-nosis of optic nerve glioma. The presence ofchiasmal enlargement gave rise to anappearance identical to that of optic chiasmglioma on unenhanced MRI. Marked enhance-ment around the margins of the lesion was feltto represent arachnoid gliomatosis andenhancement in the region of the lateralgeniculate body was also in keeping with adiagnosis of optic nerve glioma. The presenceof small areas of leptomeningeal enhancementon the base of the hypothalamus and ofenhancement of the infundibulum were notedon the original MRI examination and should,in retrospect, have suggested more extensiveleptomeningeal disease.

In conclusion, leptomeningeal sarcoidosisaffecting the optic chiasm may closely mimicoptic nerve glioma. The presence of atypicalradiological features such as leptomeningealenhancement or peripheral enhancement of anenlarged chiasm should suggest aninflammatory process. If the risk of chiasmalbiopsy is considered too great then diseaseprogression should be monitored frequentlyusing contrast enhanced TI-weighted MRI.

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2 Douglas AC, Maloney AFC. Sarcoidosis of the centralnervous system. J Neurol Neurosurg Psychiatry 1973; 36:1024-33.

3 Hayes WS, Sherman JL, Stem BJ, Citrin CM, Pulaski PD.MR and CT evaluation of intracranial sarcoidosis. AJNR1987; 8: 841-7.

4 Miller DH, Kendall BE, Barter S, et al. Magnetic resonanceimaging of central nervous system sarcoidosis. Neurology1988; 38: 378-83.

5 Pentland B, Mitchell D, Cull RE, Ford MJ. Central nervoussystem sarcoid. N Engl J Med 1985; 220: 457-465.

6 Rootman J. Diseases ofthe orbit: a multidisciplinary approach.Philadelphia: Lippincott, 1988.

7 Jackson A, Fawcitt RA. Orbital imaging. In: Gillespie JE,Gholkar A, eds. Magnetic resonance imaging and computedtomography of the head and neck. 1st edn. London: Chapman& Hall Medical, 1994; 63-97.

8 Imes RK, Hoyt WF. Childhood chiasmal gliomas: update onthe fate of patients in the 1969 San Franscisco study. Br JfOphthalmol 1986; 70: 179-82.

9 Delaney P. Neurologic manifestations in sarcoidosis. AnnIntern Med 1977; 87: 336 -45.

10 Seltzer S, Mark AS, Atlas SW. CNS sarcoidosis: evaluationwith contrast-enhanced MR imaging. AJNR 1991; 12:1227-33.

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