Case Report neup_1254 280..284

JC virus granular neuronopathy andrhombencephalic progressive multifocal

leukoencephalopathy: Case report and review ofthe literature

Julia Keith,1 Juan Bilbao1 and Roy Baskind2

1Department of Anatomical Pathology, Sunnybrook Health Sciences Centre, and 2Department of Medicine, Division ofNeurology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada

JC virus (JCV) granular neuronopathy remains an under-appreciated phenomenon whereby JCV inhabits neuronsin the granular layer of the cerebellum causing neuronalloss, gliosis and a clinical cerebellar syndrome. The follow-ing case describes a man with sarcoidosis and idiopathicleukopenia who developed a clinical cerebellar syndromedue to JCV granular neuronopathy, followed by neurologi-cal decline due to rhombencephalic progressive multifocalleukoencephalopathy. This case reminds us of the ability ofJCV to produce dual neuropathology which includes JCVgranular neuronopathy, and the pathogenesis and clinicalimplications for this phenomenon are discussed.

Key words: granular, JC virus, neuronopathy, PML,rhombencephalic.

INTRODUCTION

JC virus (JCV) granular neuronopathy remains an under-appreciated phenomenon whereby JCV, which usuallyinfects glia in the CNS resulting in demyelination (progres-sive multifocal leukoencephalopathy or PML), inhabitsneurons in the granular layer of the cerebellum causingneuronal loss, gliosis and a clinical cerebellar syndrome.The following case describes the clinical course and pathol-ogy of a patient with dual JCV pathology: PML limited tothe rhombencephalon and JCV granular neuronopathy.

CLINICAL SUMMARY

A 74-year-old man had a past medical history of cutaneoussarcoidosis controlled with a combination of prednisone12.5 mg daily and methotrexate 10 mg weekly, and lym-phopenia with a total lymphocyte count of 0.3 ¥ 109 cells/L(normal 1–3.5 ¥ 109 cells/L) and CD4 count of 0.26 ¥ 109

cells/L (normal 0.5–1.5 ¥ 109 cells/L). Investigations forlymphoma were negative and an etiology for his lymphope-nia was never found. His medical history was also notablefor psoriasis treated with Plaquenil, squamous cell carci-noma of the lung resected 6 years previously, and smoking(75 pack year history). His first contact with a neurologistwas for headaches caused by cervical spondylosis, at whichtime his neurological examination was normal.Two monthsafter this assessment the patient noticed gait unsteadinessand had several falls. Neurological examination docu-mented a wide-based gait and dysmetria of the left arm.

Magnetic resonance imaging (MRI) of the brain showedno rhombencephalic abnormalities and an old lacunarinfarct of the right caudate head. Routine bloodwork wasunremarkable, other than the previously documented lym-phopenia. The CSF was eucellular with normal protein andglucose. No recurrent lung cancer was seen on chest CTscan. Testing for paraneoplastic antibodies was negative,including anti-Hu, anti-Yo, anti-Ri, anti-NMDA (N-methylD-aspartate), anti-AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and anti-VGKC (voltage gatedpotassium channels). Molecular studies for autosomal-dominant spinocerebellar ataxias (SCA1, 2, 3, 6, 7, 8 and 17)and fragile X ataxia syndrome were normal.

Over the next 5 months the patient’s cerebellar symp-toms worsened and he became wheelchair-bound. Twofurther MRIs showed progressive left middle cerebellar

Correspondence: Julia Keith, MD, FRCPC, Department of Anatomi-cal Pathology, Sunnybrook Health Sciences Centre, Room E4-32, 2075Bayview Avenue,Toronto, ON, Canada M4N 3M5. Email: julia.keith@sunnybrook.ca

Received 07 July 2011; revised and accepted 10 August 2011; pub-lished online 9 October 2011.

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Neuropathology 2012; 32, 280–284 doi:10.1111/j.1440-1789.2011.01254.x

© 2011 Japanese Society of Neuropathology

peduncle signal change (Fig. 1) without contrast enhance-ment or restricted diffusion. The favored radiological diag-noses was low-grade glioma and less likely considerationsincluded lymphoma and metastases (which usuallyenhance), infarction (which should have diffusion restric-tion) and PML. A CSF sample was sent for JCV PCRwhich was negative. Six months after his neurological pre-sentation the patient developed left sixth cranial nervepalsy, became bedbound and died. A post-mortem exami-nation limited to the brain was requested as the etiology ofthe cerebellar syndrome had remained elusive.

PATHOLOGICAL FINDINGS

Macroscopically, the fresh brain weighed 1620 g, patchynon-occlusive atherosclerosis was seen in the basal vascu-lature, and there were lacunes in the right caudate andright thalamus. Foci of grey discoloration were seen in thepons and cerebellar white matter and focal cerebellar cor-tical atrophy was noted.

Histologic examination revealed numerous confluentfoci of myelin pallor on HE with LFB stained sectionsthroughout the pons (including a large focus in the leftmiddle cerebellar peduncle), medulla and cerebellum(Fig. 2a,b). These regions of myelin pallor containednumerous myelin-laden macrophages but no other inflam-matory cells were present and the axons were relativelypreserved (Fig. 2c). Scattered astrocytes with bizarrenuclear pleomorphisms were present (Fig. 3a), as wereenlarged, round, oligodendroglial cells with intra-nuclearviral inclusions (Fig. 3b). The presence of JCV was con-firmed using in situ hybridization (ISH) (Fig. 3c). The diag-nosis was PML limited to the rhombencephalon as nodemyelinating lesions were seen in the hemispheric whitematter.

The second significant microscopic finding was areasof granule neuron depletion and intense gliosis scatteredthroughout the cerebellar cortex (Fig. 4a,b), with relativesparing of the Purkinje cell and molecular layers, oftenflanked by relatively normal-appearing cerebellum.Several remaining cells in the granular layer, often adja-cent to the areas of neuronal loss, contained JCV on ISHtesting, and double labelling with ISH and either neurofila-ment or GFAP immunohistochemistry confirmed thatsome of these cells were neurons (Fig. 4c).These cerebellarcortical abnormalities were indicative of a second JCV-induced neuropathology, JCV granular neuronopathy.

DISCUSSION

JCV is a small double-stranded DNA (dsDNA) polyomavirus affecting most people via an asymptomatic childhoodinfection with JCV, evidenced by a 75% positive serology

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Fig. 1 (a) Axial T2-weighted fluid-attenuated inversion recoveryMRI showing signal change in the left middle cerebellar peduncleand white matter. (b) Axial T1-weighted contrast-enhanced MRIshowing signal change in left middle cerebellar peduncle andwhite matter which does not enhance with contrast.

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rate for anti-JCV antibodies in adults.1 After this asymp-tomatic infection the virus enters a latency phase in humankidneys, and upon significant immunosuppression the virusundergoes genetic rearrangements in the non-coding“regulatory region” of its genome, is reactivated, dissemi-nates hematogenously, and enters the brain.2

Traditionally JCV was thought to reside exclusivelywithin glia, especially oligodendroglia, in which the viruscauses cytolysis and an inability to maintain myelination.This phenomenon is demonstrated by the disease inwhich this virus is usually associated, PML, the histologyof which is well demonstrated by this case. PML causes 33deaths per million persons, with 2.1% of AIDS patientsdying with PML1. The majority of PML cases are fatalas there is no known effective anti-viral therapy, andmanagement strategy is improvement of the patient’simmunosuppression. Although the etiology of immuno-suppression in PML is most frequently HIV (79% ofcases), PML can also occur in hematological malignancy(13%), organ transplant recipients (5%) and otherautoimmune disorders (3%).3 The latter usually consist oflupus or rheumatoid arthritis, but PML in the setting ofsarcoidosis has been described.

The clinical diagnosis of PML relies on two investigativetools. The first is neuroimaging, which shows white matterCT hypodense, MRI T2-weighted/fluid-attenuated inver-sion recovery (FLAIR) hyperintense lesions that cross vas-cular territories and have neither mass effect nor contrastenhancement. The usual distribution of demyelinatinglesions on imaging is the hemispheric white matter, with athird of patients having both rhombencephalic and hemi-spheric white matter lesions, and 4% of patients havingPML exclusively within the rhombencephalon.4 Thesecond tool is CSF sampling, which usually has a normalcell count and protein level, but on which PCR for JCV canbe performed. Recently, the sensitivity of CSF PCR forJCV has been called into question, with some studiesquoting as low as 75% sensitivity,5 with false negative rateshighest in patients with minimal immunosuppression andhigher CD4 counts.6

The traditional notion of exclusively glial inhabitationwithin the CNS has been challenged by the description oftwo entities resulting from intraneuronal JCV particles. Asingle case report of JCV encephalitis demonstrated theability of JCV to cause significant atypia and cytolysis ofcortical pyramidal neurons.7 Of relevance to the presentcase is the phenomenon of JCV granular neuronopathy.The first description of the effects of JCV on the granulecell layer of the cerebellum was by E.P. Richardson, who in1961 described the neuropathology of 10 PML cases:8

“In (3 of the 10 cases) there were, in lesions of thegranule-cell layer of the cerebellar cortex, large

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Fig. 2 (a) HE/LFB-stained section of the pons showing multipleareas of myelin pallor including a large area in the left middlecerebellar peduncle. (b) HE/LFB-stained section of cerebellumshowing multiple confluent areas of myelin pallor in the whitematter. (c) HE/LFB stained section of cerebellar white matter ¥10highlighting multiple well circumscribed areas of myelin pallorwith foamy histiocytes.

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nuclei, which, from their form, location and arrange-ment, have been tentatively identified as altered cer-ebellar granule neurons.”

Six cases of PML were described by Kuchelmeister9

which had “peculiar changes in the cerebellar granularlayer” consisting of cells with enlarged, hypochromaticnuclei. The term granular cell neuronopathy was coined byKoralnik10 who described an HIV positive patient withcerebellar symptoms whose biopsy of the cerebellumshowed focal areas of granular neuron loss with cells resem-bling those described previously, but no PML lesions. Usingdouble immunohistochemical labelling, it was determinedthese unusual cells were JCV-infected granular layerneurons. The only significant study of this phenomenon todate suggests that JCV granular neuronopathy is likelymore prevalent than previously appreciated. Wüthrichet al.11 examined cerebellar sections from 43 PML cases (40of whom were HIV positive) plus 35 HIV positive controlsand 37 HIV negative controls. They found that 51% of thePML cases had JCV infection of the granular neurons in thecerebellum. Most of these cases also had demyelinatinglesions in the cerebellum; however, JCV granular neuron-opathy was also present in 7% of cases with PML of hemi-spheric white matter but not of the cerebellum and 3% ofHIV positive controls without PML. It was not seen in anyHIV negative controls. They then described four differenthistologic patterns of JCV granular neuronopathy, with ourcase resembling Type 4 (JCV infected neurons confluentwith cavitated PML lesions, plus moderate to extensiveareas of granular neuronal loss).

Clinically JCV granular neuronopathy presents withsubacute or chronic cerebellar dysfunction and cerebellarcortical atrophy on MRI. Of relevance is the fact that ourpatient’s cerebellar symptoms preceded the appearance ofthe white matter abnormalities on MRI. Our case is similarto that reported by Granot et al. of a sarcoidosis patientwith combined PML and granular neuronopathy on cer-ebellar biopsy.12

In summary, our case reminds us of the ability of JCV toinfect neurons within the CNS, especially granule cellneurons, with resulting neuronal loss, gliosis and a clinicalcerebellar syndrome. As awareness of different types ofJCV infection of the CNS other than PML increasesamong the neuropathology community, the authorssuspect that, as demonstrated by Wüthrich et al.,11 this

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Fig. 3 (a) HE/LFB-stained section of cerebellar white matter ¥40showing pleomorphic astrocytes (arrowhead) with foamy mac-rophages and preserved axons in the background. (b) HE/LFB-stained section of cerebellar white matter showing enlargedoligodendroglia with viral inclusions. (c) In situ hybridizationdemonstrates JCV within the glia of the cerebellar white matter.

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under-appreciated phenomena will be recognized as a fre-quent occurrence in PML patients.

ACKNOWLEDGMENTS

The authors are grateful to Dr Patrick Shannon, neuro-pathologist, Mount Sinai Hospital, Toronto, Ontario,Canada, for providing the ISH study for JCV, and to MsBeverly Young, Sunnybrook Health Sciences Centre,Toronto, Ontario, Canada for technical assistance with thiscase.

REFERENCES

1. Love S. Wiley C. Viral infections. In: Love S, Louis DN,Ellison DW, eds. Greenfield’s Neuropathology, 8th edn.Vol 2, London: Arnold, 2008; 1340–1343.

2. Tan CS, Koralnik IJ. PML and other disorders causedby JCV: clinical features and pathogenesis. LancetNeurol 2010; 9: 425–437.

3. Ghuens S, Pierone G, Peeters P, Koralnik IJ. PML inindividuals with minimal or occult immunosuppres-sion. J Neurol Neurosurg Psychiatry 2010; 81: 247–254.

4. Whiteman ML, Post MJ, Berger JR et al. PML in 47HIV-seropositive patients: neuroimaging with clinicaland pathologic correlation. Radiology 1993; 187: 233–240.

5. Weber T, Frye S, Bodemer M, Otto M, Luke W. Clini-cal implications of nucleic acid amplification methodsfor the diagnosis of viral infections of the nervoussystem. J Neurovirol 2006; 2: 175–190.

6. Wang Y, Kirby JE, Qian Q. Effective use of JC virusPCR for diagnosis of progressive multifocal leukoen-cephalopathy. J Med Microbiol 2009; 58: 253–255.

7. Wüthrich C, Dang X, Westmoreland S et al. FulminantJCV encephalopathy with productive infection of cor-tical pyramidal neurons. Ann Neurol 2009; 65: 742–748.

8. Richardson EP. Progressive multifocal leukoencepha-lopahy. NEJM 1961; 265: 815–823.

9. Kuchelmeister K, Bergmann M, Gullotta F. Cellularchanges in the cerebellar granular layer in AIDS-associated PML. Neuropathol Appl Neurobiol 1993; 19:398–401.

10. Koralnik IJ. JCV granule cell neuronopathy: a novelclinical syndrome distinct from PML. Ann Neurol2005; 57: 576–580.

11. Wüthrich C, Cheng YM, Joseph JT et al. Frequentinfection of cerebellar granule cell neurons by polyo-mavirus JC in PML. JNEN 2009; 68: 15–25.

12. Granot R, Lawrence R, Barnett M et al. What liesbeneath the tent? JCV cerebellar granule cell neuron-opathy complicating sarcoidosis. J Clin Neurosci 2009;16: 1091–1092.

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Fig. 4 (a) HE/LFB-stained section of the cerebellum ¥10showing focal granular neuron depletion and gliosis. (b) HE/LFB-stained section of the cerebellum ¥10 showing granule neurondepletion and gliosis with adjacent demyelinating lesion. (c) Duallabelling with JCV ISH and GFAP immunohistochemistry ¥40showing JCV within cerebellar granule neurons lacking GFAPexpression.

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