primary orbital schwannomas

British Journal of Ophthalmology, 1982, 66,194-204

Primary orbital schwannomasJACK ROOTMAN,' CHAIM GOLDBERG,2 AND WILLIAM ROBERTSON3

From the 'Departments of Ophthalmology and Pathology, University of British Columbia andVancouver General Hospital; the 2Department of Ophthalmology, University of British Columbia andVancouver General Hospital; and the 3Department of Radiology, Vancouver General Hospital, Canada

SUMMARY Seven histologically proved cases of primary orbital schwannoma have been seen at theUniversity of British Columbia Orbital Clinic between September 1976 and December 1980. Wedescribe here their varied clinical presentations, preoperative investigations, operative findings,and appearances on light and electron microscopy. Although no single feature is pathognomonic, amultiplicity of clinical, radiographic, and surgical features point to this lesion. Of preoperativeinvestigations the computed tomography scan was the most helpful, especially in localising thelesion. Of the 7, 4 were intraconal and 3 were extraconal. The surgical approach was dictated bytumour site and included anterior, lateral, and panoramic orbitotomies. At surgery the nerve oforigin of 4 of the tumours was identified. All tumours were excised totally or subtotally. There hasbeen no recurrence to date.

Schwannomas account for 1% of orbital tumours' 2and may arise anywhere within or adjacent to theorbit.3 We have seen 7 histologically proved cases ofschwannomas in the Orbital Clinic at the Universityof British Columbia between September 1976 andDecember 1980. We describe here their varied clinicalpresentations, preoperative investigations, operativefindings, and appearances on light and electronmicroscopy.

Materials and methods

During the period from September 1976 to December1980 484 cases were seen in the Orbital Clinic at theUniversity of British Columbia, of which 123 repre-sented mass lesions. Seven of these were found to beschwannomas, representing 1-4% of all orbital casesseen and 5-7% of mass lesions.

Diagnostic investigations included computedtomography (CT) scan (EMI 1010S or GE 8800), Aand B ultrasonography, and skull series. Tomographyand contrast arteriography were used when indicated.

Surgical approaches included lateral, anterior, andpanoramic orbitotomies, depending on the specificpreoperative localisation.

Postoperatively the excised tumour was submittedfor light and electron microscopic analysis.

Correspondence to Dr J. Rootman. Department of Ophthalmology,2550 Willow Street. Vancouver. BC. Canada V5Z 3N9.

CLINICAL PRESENTATIONSOf the 7 cases 4 were intraconal and 3 were extra-conal. The latter group consisted of the followingsites: ethmoid sinus, superior orbit and upper lid, andinferoanterior orbit. Five case histories will bepresented.

Case reports

CASE 1A 60-year-old Caucasian man had noted slowly pro-gressive right proptosis from age 24. There were noother ophthalmic complaints until August 1976, whenhe complained of blurred vision of his right eyefollowed by intermittent horizontal diplopia. Inaddition he had occasional frontal pain andtenderness.

Best corrected right visual acuity was 6/7-5. Theright eye was 8 mm proptotic and displaced laterally 2mm (Fig. 1). The orbit was ballotable and the globecould be retropulsed. He had a right hypertropia of 2prism dioptres in up gaze and a 4 prism dioptreexotropia in left lateral gaze. The right optic nervehead appeared somewhat pale. The remaining oph-thalmic and physical examination was unremarkable.CT scan showed a smooth, well-defined, oval,

intraconal mass lesion in the posterior one-half of theright orbit. It demonstrated mild, uniform enhance-ment, and a focal area of calcification was seencentrally in the mass (Fig. 2). Orbital x-rays were

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Primarv orbital schwannomas

Fig. I Case 1: 60-Year-old male with long-standing rightproptosis, showing 8 mm axial and 2 mm lateraldisplacement of the globe.

normal. Carotid angiography demonstrated inferiordisplacement of the ophthalmic artery and its lateralbranch, with no tumour blush (Fig. 3).

Ultrasonography revealed an intraconal mass lesionwith a well-demarcated anterior border. Considerablesound attenuation within the tumour indicated arelatively solid nature. Some cystic areas were alsopresent.The patient underwent a right lateral orbitotomy.

A brown-yellow, encapsulated, multilobular mass wasfound within the muscle cone beneath the superiorrectus muscle and extended medially to lie adjacentto the optic nerve. The tumour had multiple darkvaricosities on it, and a large artery branched into themedial surface. Postoperatively the patient recovered

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Fig. 2 Case 1: CTscan (EM lOlOs) showingsmooth, welldefined, oval intraconal mass lesion with central calcification(arrow).

Fig. 3 Case 1. Carotid arteriogram, slubtraction view,demonstrating inferior displacement ofophthalmic arterYwith no tlumolur bllush.

uneventfully and has full ocular function withoutrecurrence (Fig. 4).

Light microscopic examination showed aschwannoma with both Antoni types A and Bpatterns, Verocay bodies, and calcification. Thetumour was encapsulated, and abnormal tumourvessels were present with perivascular lymphocyticinfiltrates.

CASE 2A 54-year-old Caucasian woman 1P5 years prior toadmission noticed a subjective right central scotomawhich she described as a 'white spot and like lookingthrough a heat wave.' Appreciation of fine detail forthe right eye diminished after that, and the visual

Fig. 4 Case 1: Postoperative photograph.

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1Jack Rootman, Chaim Goldberg, and William Robertson

Fig. 5 Case 2: CTscan (GE 8800) demonstrating apicalintraconal lesion.

acuity was noted to have fluctuated between fingercounting and 6/7-5. She denied ocular pain, photo-phobia, or changes in her facial appearance.On examination the best corrected visual acuity in

her right eye was 6/7 5. The visual field to con-frontation was diminished in the right eye. There wasa right relative afferent pupillary defect. Ocular andphysical examinations were otherwise unremarkable.CT scan showed a well-defined intraconal lesion in

the posterior aspect of the orbit displacing the opticnerve medially (Fig. 5). The posterior margin waswell defined and spared the apex. The lesion wasapproximately 1x2 cm in diameter, and showed amoderate uniform enhancement. No bone destruc-tion was evident. Carotid arteriography did notdemonstrate a blush.

Ultrasonography failed to reveal any abnormality.The patient underwent a combined frontal crani-

otomy and lateral orbitotomy panoramic approach.An encapsulated lesion 1 cm in diameter was foundwithin the muscle cone at the apex attached to thesuperior branch of the oculomotor nerve adjacent tothe optic nerve. It had fine varicosities on its surface.Because of extreme space limitations it was incisedunder the microscope, a specimen examined by frozensection, and the remaining mass carefully evacuatedleaving the adjacent nerves intact.Light microscopy showed predominantly Antoni

type A schwannomn with many Verocay bodies.Vessels within the tumour had thick walls.

Postoperatively the patient had a partial right ptosisand paresis of the right superior rectus muscle, whichremitted completely within the next 6 months.The remaining intraconal cases had long-standing

histories, and the tumours were well encapsulated,did not extend into the apex of the orbit, enhanced

Fig. 6 Case 3:32-vear-old woman with 4 mm downwarddisplacement of right globe and facial asymmetry.

mildly on CT scan, and failed to take up contrast onangiography. At surgery they were encapsulated, hadvaricosities on their surfaces, and were extirpatedintact with no postoperative problems. In one adistinct origin from the sixth nerve was noted.The following 3 cases were extraconal in location.

CASE 3A 32-year-old Caucasian woman complained of arecent onset of diplopia in up gaze. She had notedabnormality of her right upper lid 8 years prior toadmission and was aware of downward displacementof her right globe. Other than flushing of the right sideof her face she denied any other orofacial symptomsor evidence of masses elsewhere. On examination shehad a number of smooth, mobile, soft masses in herright upper lid which were tender to touch. On theright she showed 4 mm downward displacement ofthe globe, hemifacial asymmetry, and a hypotropia of4 prism dioptres, without proptosis (Fig. 6). Visualacuity, pupillary function, visual field, intraocularpressure, and fundus examinations were normalbilaterally. A CT scan done on the EML 1010Sscanner did not demonstrate a mass.An anterior orbitotomy was carried out through a

brow incision. A multilobular, yellow, solid tumourmass was identified occupying the entire roof of theorbit (Fig. 7). It extended posteriorly to the apex andappeared to come out of the superior orbital fissure.Numerous nerve-like structures were noted extendingfrom the mass. The bulk of this tumour was removedpiecemeal.

Histologically it was a typical schwannoma: encap-sulated, Antoni type A, with numerous Verocaybodies with thickened blood vessels cuffed bylymphocytes and plasma cells. Electron microscopy

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Fig. 7 Case 3: Anteriororbitotomv showing multilobular,solid tumour mass. Note surfacevessels.

showed many Schwann cells with stacked paleprocesses surrounded by a well defined basementmembrane.The patient is asymptomatic, has no evidence of

recurrence, and no sensory loss in the supraorbitaldermatome.

CASE 4A 24-year-old man noted sudden onset of a constantdull ache in the region of the inner bony margin of his

left orbit, associated with a sensation of left retro-bulbar pressure. He had a history of chronic nasaldischarge and had recently noted left ocular muco-purulent discharge and crusting of the lids on waking.On examination he had a 4 mm left proptosis and

lateral displacement of his globe. Examinations of hispupils, visual acuity, intraocular pressure, and fundiwere normal bilaterally. He had diminished nasal airmovement and hearing changes compatible with pastear disease.

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Fig. 8 Case 4: Polvtomogramdemonstrates opacification ofleftfrontal, ethmoid, and maxillarysinuses and middle turbinate.

1'97

Jack Rootman, Chaim Goldberg, and William Robertson

logically it was typical of schwannoma. The tissue wasloosely organised in some areas showing prominentnuclear palisading and numerous Verocay bodies.There was considerable nuclear pleomorphism withsome large atypical nuclei. Blood vessels werethickened and hyalinised.

CASE 5A 31-year-old East Indian man first noted inNovember 1979 a palpable mass involving the leftorbital rim and lower lid. It was associated with a localdeep, boring, knife-like pain, occurring once a week,lasting a few minutes, and resolving spontaneously.The lesion grew slowly and was biopsied by a general

Fig. 9 Case 4: CTscan (EMI 1OOs) showing mass surgeon in January 1980. The histology was equivocal,extendingfrom left ethmoid sinus into the medial aspect ofthe with a possible diagnosis of fibrous histiocytoma. Fourorbit. months later on admission to the Vancouver General

Physical examination was otherwise unremarkable.Plain films and polytomography showed opacifica-

tion of the left frontal, ethmoid, and maxillarysinuses, with bone destruction of the medial wall ofthe orbit (Fig. 8).A CT scan confirmed opacification of the left

ethmoid sinus and adjacent left middle turbinate. Asoft tissue mass bulged into the medial aspect of theleft orbit with slight indentation of the globe (Fig. 9).The lesion did not enhance.The preoperative diagnosis was mucocoele of the

left ethmoid sinus with pansinusitis.The patient underwent an ethmoidectomy through 4

a Lynch incision. At surgery the medial wall of theorbit was bowed laterally and showed bonydehiscence. Beneath the bone and within the sinusthere was a yellow-pink tumour with a fibrous Fig. 11 Case5: CTscan (GE 8800) demonstratingcapsule. It was easily peeled off and removed. Histo- thickening ofsoft tissues anterior to the left infraorbital

margin.

Hospital showed a firm, smooth, nontender, immo-bile mass 23 x25 mm involving the left lower lid andextending posteriorly over the inferior orbital margin(Fig. 10). The remainder of his ocular and physicalexamination was otherwise unremarkable.Both axial and coronal CT scans demonstrated

thickening of the soft tissues anterior to the left infra-orbital margin (Fig. 11). There was no enhancementof this area, and the lesion was not well defined butappeared to be infiltrative in nature. Tomograms ofthe left orbit showed a slight depression of the infero-laeal aspect of the orbital floor with mild localised

bony sclerosis, in keeping with a slow-growing soft-tissue mass producing pressure erosion with evidence

'~of bone invasion.A and B mode ultrasonography showed numerous

Fig. 10 Case 5: 31-year-old man with mass involving left fine interfaces within a fairly solid mass lesion.lower lid. A left anterior orbitotomy revealed a well encapsu-

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Primary orbital schwannomas

Fig. 12A CTscan (GE 8800) demonstrating intraconal,well defined mass lesion.

lated tumour with abnormal varicose vessels over-lying the surface. There were adhesions to the orbitalseptum and the periosteum of the maxillary bone.The mass appeared to extend from the infraorbitalforamen laterally and was stripped from the nerveremoving it in toto. Postoperative recovery wascomplete and uneventful.

Light microscopic examination showed a relativelyencapsulated tumour mass with numerous smallvascular channels and perivascular lymphocyticcuffing. The cells were both spindle and stellateshaped, arranged in a variety of patterns. Some werenoted to be loosely entwined within a myxoid-appearing stroma, while others were more compactlyarranged in a streaming formation. In some sections adense, homogeneous, eosinophilic, collagenousstroma was noted. Electron microscopic findings

U _J W. t. InFig. 12B Same lesion as Fig. 12A showing mildenhancementfollowing contrast injection.

supported the diagnosis of a fibrous schwannoma.

Results

All 7 patients had histologically confirmedschwannomas. None had systemic manifestations ofneurofibromatosis. Their ages at the time of presenta-tion ranged from the third'to seventh decades. Thetumour sites were 4 intraconal and 3 extraconal. Ofthe latter, one was in the ethmoid sinus, anotheranterior to the infraorbital margin, and one involvedthe superior orbit and upper lid. Displacement of theaffected globe was related to the site of the mass andranged from marked anteroinferolateral to none atall. Visual acuity on presentation was uniformly 6/7-5or better except for one case having acuity of 6/12(due to macular degeneration).

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Fig. 13A Histopathology ofanintraconal schwannomademonstrating an admixture ofcompactlv arranged interlacingfascicles (Antoni A pattern-lowerright) and more looselv arrangedcells separated bv a clear matrix(Antoni B pattern) with abackground oflvmphocvtoid cells.(Haematoxylin and eosin, x44).

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Fig. 13B Histopathology ofanother area ofthe same tumourshowing a hyalinised vessel (arrow)with an organoid cellular patterncentrally (Verocay body).Background pattern is basicallyAntoni B with lymphocytoid andlipid laden foam cells. (H. and E.x44).

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Diplopia and strabismus on a mechanical basis werenoted in 2 patients. Only one patient had an abnormalfunduscopic examination with choroidal striae andperipapillary haemorrhages.

All patients were investigated by CT scanning,which detected 6 of the 7 lesions. Of these, 4 wereintraconal, one was in the infraorbital soft tissues,and one was in the ethmoid sinus and middle turbinatewith extension into the medial aspect of the orbit.Two tumours caused medial displacement of the opticnerve, 3 caused axial proptosis, and one caused in-dentation of the globe. Four of 5 contrast CT studiesdemonstrated enhancement, which was of a milddegree (Figs. 12A, B). In all cases except one thelesions were well defined with discrete edges. The

Fig. 13C Case 1: Lightmicroscopy oftumourfrom case I

showing a basically Antoni Bpattern with a central area ofcalcification. (H. and E., x44).

shape varied from round to oval. One case hadassociated bony indentation and one had calcificationin the central part of the tumour. The intraconallesions did not follow a muscle or mimic muscleenlargement, nor did they extend into and obscurethe orbital apex.

Ultrasonography was carried out in 4 of 7 patients,all of whom had intraconal lesions. Of these, 3 weredetected. All were described as encapsulated, solidlesions with a well demarcated anterior border.Within the mass were a number of tissue interfaceswhich attenuated dramatically. A posterior bordercould not be detected.At surgery the lesions were characteristically

yellowish-tan in colour, solid, encapsulated, and had

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Fig. 14A Case 3: Electronmicrograph o'f tissuie firom case 3showing Schwann cells withinterdigitating and convoluted cellmembranes with fiew slibcelluilarorganelles and a prominentextracelluilar basement membrane.(x 18 110).

Fig. 1 4B Electron micrographfrom an intraconal schwannoma

shown in Fig. 14A. This

demonstrates 'long spacing'

collagen adjacent to a cell

membrane (x 700).

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Fig. 14C Case 2: Electronmicrograph from the lesiondescribed in case 2. Note adjacent tothe nuclear membrane is alongitludinal section ofa cilia (x8500). Insert shows a cililm in cross

section (x 66 000).

Fig. 15 Carotid arteriogram,slubtraction view, of histologicallvproved cavernous haemangiomashowing late minor pooling ofdye(between large arrowhead). Smallarrowheads define the choroidalcrescent.

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Fig. 16A Early phase, carotidarteriogram, subtraction view, ofhistologically proved optic nervemeningioma demonstratingmultiple tumour vessels.

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typical varicose, violaceous tumour vessels on theirsurface. Four nerves were specifically identified inassociation with their respective lesions, all of whichwere removed leaving the nerves of origin intact. Theassociated nerves were: superior division of the third,sixth, infraorbital, and superior division of theophthalmic nerve.

Histology was variable but typical of schwannoma,including mixed Antoni type A and B patterns (Fig.13A), tumour capsule, thick walled hyalinised vessels(Fig. 13B), perivascular lymphocytic cuffing, calcifi-cation (Fig. 13C), organoid arrangements of Schwanncells with Verocay bodies (Fig. 13B), loose col-lagenous stroma, and occasional nuclear pleo-morphism. Electron microscopy confirmed the

schwannian origin in each of the tumours (Fig. 14A).Long spaced collagen was identified in one of thetumours only (Fig. 14B). An unusual electronmicroscopic feature noted in one of the tumours wasthe presence of a typical cilia (Fig. 14C).

Discussion

Primary schwannoma rarely occurs in the orbit.Although no single feature is pathognomonic, amultiplicity of clinical, radiographic, and surgicalfeatures point to the diagnosis of this lesion. It is adisease primarily of adults, has an insidious onset, isslow growing, and is noninvasive with minimal effecton other orbital structures. The range of clinical

Fig. 16B Same lesion, late phase,demonstrating tumour blush (blackarrows); white arrows indicatechoroidal crescent.

203


presentation in our patients included optic neur-opathy, proptosis, diplopia, anterior orbital mass,and sinusitis. Of available investigations CT scan wasfound to be the most useful, particularly in localisingthe lesion, whether within the orbit or extending intoit from periorbital soft tissues or paranasal sinuses.The configuration varies from round to oval, and thetumour generally has a well-defined margin and, ifintraconal, is well demarcated posteriorly. On CTscan most lesions enhanced to a mild degree, but oncarotid arteriography there is no uptake of dye.Ultrasonography confirmed the presence of a dis-crete, encapsulated, solid-mass lesion. Other slowgrowing orbital tumours to be considered in the dif-ferential diagnosis are cavernous haemangioma,meningioma, and haemangiopericytoma. In ourexperience, on carotid arteriography, cavernoushaemangiomas show late minor pooling of the dye(Fig. 15), while meningiomas have multiple tumourvessels and a late blush (Fig. 16A, B). Haem-angiopericytomas have an early florid blush. These 3lesions when compared with schwannomas showedmore marked enhancement with contrast on CTscanning. In addition, on CT scanning schwannomastend not to follow a muscle or mimic muscleenlargement as is seen in thyroid ophthalmopathy,nor do the lesions extend into and obscure the apex ofthe orbit, as may be seen in orbital pseudotumour orintrinsic optic nerve lesions.4" Although previousseries" all describe lesions of large size, a high indexof suspicion, accurate localisation, and determinationof size by the methods described here allow small,symptom-causing lesions to be treated early and suc-cessfully, as demonstrated in case 2. Primary orbitalschwannomas are typically benign, encapsulated,noninvasive tumours. Thus surgical excision as adefinitive therapy is indicated.The surgical approach, whether anterior, lateral, or

combined lateral-orbitotomy and frontal-craniotomy,was dictated by the location of the lesions as deter-mined by preoperative investigations. Surgicalremoval may be total or subtotal, in piecemealfashion, or by evacuation of the tumour from withinits capsule. The type of removal is dictated by thelocation and attachments to adjacent structures.Because of the peripheral outpouching characteristicof schwannomas they may be successfully stripped ofthe nerve of origin by microscopic techniques. Like

other authors, in a follow-up ranging from 6 monthsto 5 years we have had no recurrences.8'o

Histological examination also showed the varia-bility of the tumours.23 Antoni types A and B werefound in addition to more fibrous types and some areasof cellular pleomorphism. Electron microscopy con-firmed the Schwann cell origin in all cases and wastypical of Schwann cell tumours previouslydescribed.2 The unusual finding of cilia in one case isnot a specific feature of schwannomas but has beendescribed in many tumours of both epithelial andmesenchymal origin.12

In conclusion, primary orbital schwannomas are arare orbital and periorbital tumour with variableanatomical and histological expressions. Preoperativedifferential diagnosis of a slow-growing soft tissueorbital or periorbital mass includes schwannoma.Although CT scan is helpful in localising and identify-ing the lesion, no single pathognomonic investigativeprocedure or feature exists. Rather a constellation offeatures point to this diagnosis. Surgical excision isindicated and to date has been successful.

References

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2 Jones IS. Jakobiec FA. Diseases o.f the Orbit. Hagerstown:Harper and Row. 1979.

3 Harken JC. Reid RJ. Turmours of the Periperipheral NervousSvstem: Atlas of Tuimouir Pathology. Second Series. Fascicle.Washington. DC: Armed Forces Institute of Pathologv. 1969.

4 Nugent RA. Rootman J. Robertson WD. Lapointe J. HarrisonPR. CT features and classification of acute orbital pseudo-tumours. Am J Neluroradiol in press..

5 Wing SD. Hursaker JN. Anderson RE. Van Dvle HJ. L. OsbornA. Direct sagittal computed tomographv in Graves' ophthal-mopathv. i Compluter Assisted Tomographv 1979: 3: 820-4.

6 Enzmann D. Donaldson SS. Marshall WH. Kriss JP. Computedtomographv in orbital pseudotumour (idiopathic orbital inflam-mation). Radiology 1976: 120: 579-601.

7 Trokel SL. Hilal SK. Recognition and differential diagnosis ofenlarged extraocular muscles in computed tomographv. Am JOphthalmol 1979: 87: 503-12.

8 Rottino A. Kellv AJ. Specific nerve sheath tumour of orbit. ArchOphthalmol 1941; 26: 478.

9 Alman M. Fraver WC. Hedges TR. Orbital neurilemmoma. AnnOphthalmol 1977:9: 1409-13.

10 Schmitt E. Spoerri 0. Schwannomas of the orbit. Acta Neiurochir(Wien) 1980: 53: 79-85.

11 Duke-Elders S. Syvstem of Ophthalmology. London: Kimpton.1974: 13(2).

12 Font RL. Jacobiec FA. The role of electron microscopy inophthalmic pathology. In: Trump BF Jones RT. eds. DiagnosticElectron Microscopv. New York: Wilev. 1979: 2.

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