30ournalof Neurology, Neurosurgery, and Psychiatry 1992;55:300-303

Meningeal sarcoidosis, pseudo-meningioma, andpachymeningitis of the convexity

D Ranoux, B Devaux, C Lamy, JY Mear, F X Roux, J L Mas

AbstractTwo cases of meningeal sarcoidosis withunusual and misleading presentations arereported. In the first case, CT scan,angiographic, and MRI findings wereindistinguishable from those ofmeningio-ma. CSF pleiocytosis may help in diag-nosing sarcoid pseudo-meningioma. Thesecond patient had transient focal deficitsand pachymeningitis of the convexity. Thetransient deficits were probably of epi-leptic origin based on their response toantiepileptic treatment. The diagnosis ofneurosarcoidosis was made only aftermeningeal biopsy, despite thoroughinvestigations.

Neurological symptoms, including cranialneuropathies, aseptic meningitis, hydrocepha-lus, intracranial masses, encephalopathies,seizures, peripheral neuropathies, and myo-pathies, develop in 2% to 5% of patients withsarcoidosis.' Symptoms of meningeal involve-ment are protean and may take the form ofsubacute, chronic, or recurrent meningitis.Many patients are asymptomatic.' 2We report two unusual and misleading

presentations of sarcoid meningeal involve-ment. One mimicked a meningioma, bothclinically and radiologically. The other patienthad transient focal deficits and pachymeningi-tis of the convexity. The diagnosis was madeonly after meningeal biopsy despite thoroughinvestigations.

Centre RaymondGarcin, H6pital SainteAnne, 1 rue Cabanis,75674 Paris Cedex 14,FranceService de NeurologieD RanouxC LamyJY MearJ L MasService deNeurochirurgieB DevauxF X RouxCorrespondence to:Professor Mas.Received 1 May and inrevised form 4 July 1991.Accepted 17 July 1991

Case reportsCASE 1

A 32 year old West Indian woman was admit-ted with a two month history of continuous leftsided retro-orbital headache associated withparaesthesia of the left side of her face.Pulmonary and ocular sarcoidosis had beendiagnosed in 1981, and she was being treatedwith prednisone (100 mg/day) and dapsone(100 mg/day). Neurological examinationrevealed hypesthesia around the left fifth crani-al nerve with decreased corneal reflex and a leftptosis. The erythrocyte sedimentation rate(ESR) was 23 mm in the first hour. Theangiotensin-converting enzyme (ACE) activityand chest x ray pictures were normal. A CTscan showed a slightly hyperdense homoge-neous contrast-enhancing mass lying alongside the left cavernous sinus (fig la). Thislesion was hypointense and surrounded byoedema on axial T2-weighted MR images (fig

lb) and was enhanced on TI-weighted gado-linium MRI (fig 1 c). Carotid angiographyshowed a slight stenosis of the C5 segment ofthe left internal carotid artery. Selective leftexternal carotid angiography showed a vas-cular lesion lateral to the carotid siphon,supplied by the middle meningeal artery (figid). Cerebrospinal fluid was normal except forelevated proteins (0-85 g/l). A diagnosis ofmeningioma was made, and the patient wastreated with carbamazepine.She was readmitted 16 months later because

of worsening headaches and diplopia. Exam-ination showed trigeminal hypesthesia, ptosisand paresis of the medial rectus on the left. CTscans and MRI showed an increase in the sizeof the lesion. A craniotomy revealed a firm,whitish tissue which was adherent to the dura,extended to the cavernous sinus, and reachedthe sphenoid wing. The lesion, grossly resem-bling a meningioma, was partially removed.The histological examination showed multipleepithelioid granulomas without necrosis.Prednisone was increased to 50 mg per day.The left ptosis, headaches, and diplopiaresolved within a few days.

CASE 2A 48 year old white woman had a four monthhistory of recurrent episodes of left hemipar-esis. These attacks of weakness were of acuteonset, lasted five to 10 minutes, and weresometimes preceeded by a right temporalheadache. They always affected the left armand sometimes the left leg. In addition sheexperienced unrelated attacks of clonic move-ments of her left hand, lasting a few minutes.Her medical history was unremarkable. Onadmission examination revealed weakness andastereognosis of her left hand. An EEG showedparoxymal activity in the right temporal region,increased by hyperventilation. She receivedphenobarbitone and the attacks stopped. PlainCT scan (fig 2a) showed increased density ofthe gyri of the right temporo-parieto-occipitaland left occipital regions, which enhanced aftercontrast. There was a large area of hypodensityin the white matter of the right hemisphere andleft occipital region. TI-weighted MRI showeda slight hypointense signal of the white matterwith mass effect. On T2-weighted sections thenormal high signal intensity of the sulci wasreplaced by a hypointense signal, whichenhanced after gadolinium injection (fig 2b, c).CSF examination revealed a white cell count of608 mm3 with 80% lymphocytes, 10% mono-cytes, and 8% neutrophils, a protein content of1 30 g/l, and a glucose concentration of

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Meningeal sarcoidosis, pseudo-meningioma, and pachymeningitis of the convexity

IFigure la CT scan:contrast-enhancing mass(arrow) lying along leftcavernous sinus. (b)T2-weighted MRI(2000/90); lesion (arrows)hypointense compared tonomal brain. (c)Tl-eighted MRI (SE48115) with injection ofgadolinium; enhancementof lesion. (d) Selectiveexternal carotidangiography; lesion(arrow) fed by branches ofmiddle meningeal artery.

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1 84 mmol/l. CSF cultures for acid-fast organ-isms and fungi, india ink preparation, andcryptococcal antigen study were negative. TheESR was 23 mm in the first hour. ACEconcentration in serum and CSF, tuberculintest (10 units), liver and salivary gland biopsyspecimens, thoracic CT scan, fibreoptic bron-choscopy, Gallium scintigraphy, and extensiveserological studies all yielded normal or neg-ative results. The pulmonary function testsshowed a significant decrease in the diffusioncapacity. Despite the negativity of the acid-fastorganisms cultures, the patient was treatedwith antituberculous drugs.A meningeal and cortical biopsy was per-

formed two months after admission. The durawas tense and adherent to the cortex. Thebrain surface was yellowish and rubbery.

Microscopic examination revealed a fibrousthickening of the meninges and nodular granu-lomatous lesions, without central necrosis.Some follicles had a perivascular distribution.The walls of some vessels were invaded bylymphocytes with disruption of the internalelastic lamina. Cultures for bacteria, acid-fastorganisms, and fungi were negative. The cort-ical samples showed no abnormality. Thesefindings were consistent with the diagnosis ofsarcoidosis. The patient was treated with pred-nisone (1 mg/kg per day) with continuation of

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Ranoux, Devaux, Lamy, Mear, Roux, Mas

Figure 2a CT scan without contrast; spontaneousincreased density and thickening of suki of righttemporo-parieto-occipital and left occipital regions. Largehypodensity in white matter. (b) T2-weighted MRI(2200190); large area of hypersignal in white matter withmass effect. Normal signal of sulci replaced by hypointensesignal. (c) Tl-weighted images MRI (600115) withinjection ofgadolinium; enhancement of sukicorresponding to hypointense linear images seen on T2sequences.

antituberculous therapy. Two months later herclinical examination was normal. A CT scan

and MRI showed a clear decrease in the size ofwhite matter lesions and the persistance of thelow signal in the affected sulci.

DiscussionThe diagnosis of meningeal sarcoidosis in case

1 was preoperativally mistaken for meningio-ma. This had also occurred in the few pre-

viously reported cases of sarcoid pseudo-meningioma.2-8 Radiological investigationscannot differentiate between the two diseases.In all cases of sarcoid pseudo-meningioma, CTscan showed an homogeneously enhancingmass and, in two cases,7 8 skull x ray picturesrevealed hyperostosis of the sphenoid wing. In

addition, selective external carotid angio-graphy may reveal a blush,8 as seen in our firstcase. MRI findings in sarcoid pseudo-menin-gioma have not been reported. In case 1, thelesion was clearly hypointense on T2-weightedsequences and enhanced after admininstrationof gadolinium. Meningiomas are usuallyhyperintense or isointense of T2-weightedsequences but 9% to 18% are hypointense.9CSF examination may help in diagnosingsarcoid pseudo-meningioma when it reveals apleocytosis,24 which has not been reported inmeningiomas.10 In case 1, the CSF cell countwas normal, but the patient was receivingcorticosteroids at the time of the lumbarpuncture. We suggest that patients with aknown sarcoidosis and evidence of an antracra-nial mass undergo a lumbar puncture (if notcontraindicated by the volume of the lesion)and receive a trial of steroids before surgery.Radical removal may be justified only if thelesion is causing important neurologicalimpairment.

Pachymeningitis of the convexity is a rarepresentation of neurosarcoidosis.1 -16 Head-aches are the most common clinical featurefollowed by seizures. Two patients have pre-sented with transient focal deficits"6 (case 2).In view of the prevalence of affected smallvessels and subclinical infarctions at necropsy

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Meningeal sarcoidosis, pseudo-meningioma, and pachymeningitis of the convexity

of patients with neurosarcoidosis'7 an ischae-mic mechanism must be considered. In oursecond case, however, an epileptic origin ismore likely because the attacks of transientfocal deficit disappeared with anticonvulsants,and the patient had also unrelated episodes offocal seizures. Negative phenomena of epi-leptic origin are rare but can occur especially inparietal lobe lesions.18 CSF has shown non-specific elevation of the protein content orpleocytosis, or both. On CT scan granuloma-tous thickened meninges appear as slightlyincreased density with moderate or densehomogeneous enhancement. This aspect hasbeen reported in pachymeningitis with variouscauses.9The clear gyral enhancement seen incase 2 is probably explained by extension ofthemeningeal infiltrative process through theVirchow-Robin spaces.'3 In two patients withsarcoid pachymeningitis of the convexity20MRI has shown an isointense signal relative tobrain on Tl-weighted sequences and hetero-geneously hyperintense or predominantlyhypointense on T2-weighted sequences. Thevery hypointense signal of the sulci observed incase 2 on T2-weighted sequences may berelated to the fibrous thickening of the menin-ges noted at the microscopic examination ofthe meningeal biopsy specimen.The diagnosis of sarcoidosis is difficult when

neurological involvement is the first or onlymanifestation of the disease. In fact no reliablediagnostic test for neurosarcoidosis exists. Theyield from liver, salivary gland, transbronchialor muscular biopsy specimens in the diagnosisof clinically isolated neurosarcoidosis has notbeen evaluated. These specimens may remainnegative in histologically-proven neurosarcoi-dosis. Even necropsy may fail to reveal system-ic disease.2' Our second case, as well as othercases reported emphasise the difficulty ofsubstantiating the diagnosis of neurosarcoido-sis without cerebral or meningeal biopsy. Mak-ing the diagnosis early in the course of the

disease is important as the development ofmeningeal fibrosis may limit response to ste-roids.

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