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Competing Interests: R. K. Gandhi Mehta MD has received research funding from Ionis pharma and UCB. The remaining author has no funding or conflicts of interest to disclose.

Progressive multifocal leukoencephalopathy (PML) is an opportunistic central nervous system infection caused by the human polyomavirus 2, leading to demyelination from oligodendrocyte death and rapid neurologic decline. Most commonly, PML affects patients in immunocompromised states. However, rare reports of PML in an immunocompetent host exist. Here, we report two cases of PML in older individuals with chronic kidney disease (CKD). CKD can ultimately lead to immune system dysfunction and place patients in a relatively immunosuppressed state. Testing for JC virus should remain a consideration for rapid, unexplained neurologic decline even without known immunocompromised status in the appropriate clinical setting., (© 2023. Fondazione Società Italiana di Neurologia.)

Background: The incidence of progressive multifocal leukoencephalopathy (PML) in people living with HIV (PLWH) is 2%-4%. Currently, there is no effective therapeutic strategy for the treatment of PML in PLWH, resulting in a mortality of up to 50%. This study aimed to identify risk factors of death and prognostic markers in people living with HIV with PML., Methods: A retrospective cohort study of AIDS-related PML individuals was conducted from January 1, 2015, to October 1, 2022, in Shanghai, China. PLWH who were diagnosed with PML for the first time were included. Kaplan-Meier curve and Cox regression were used to analyze the survival and its predictors. Levels of inflammatory markers and immune checkpoint inhibitors in blood and cerebrospinal fluid (CSF) were measured in the prestored samples using bead-based multiplex assay Indolamine 2,3-dioxygenase was determined using ELISA., Results: Twenty of 71 subjects had initiated antiretroviral therapy (ART) before PML onset and no patients discontinued ART during this period. In total, 34 patients (47.9%) had opportunistic infections (OIs), the median CD4+ T cell count was 73.0 (33.0-149.0) cells/μL. The estimated probability of survival at six months was 78% (95% confidential intervals [CIs]:0.63-0.85). OIs, low CD4+ T cell count were associated with lower estimated six-month survival (hazard ratio 8.01, 95% CIs: 1.80-35.00, P=0.006 and 5.01, 95% CIs:1.57-16.03, p=0.007). Indolamine 2,3-dioxygenase activity in CSF of non-survivors group were higher than survivors group (p<0.05)., Conclusions: The survival rate of AIDS-related PML in the modern ART era was higher than the survival rate a decade ago. Low CD4+T cell count, OIs, were all associated with death of individuals with AIDS-related PML. The role of IDO in AIDS-related PML warrant further investigation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Jiang, Song, Liu, Mei, Sun, Qi, Wang, Song, Tang, Yang, Xu, Zhao, Shen, Zhang and Chen.)

Introduction: Progressive multifocal leukoencephalopathy is a rare but often fatal complication of some multiple sclerosis treatments. Although it has mainly been associated with natalizumab treatment, its appearance with other immunosuppressive therapies has also been reported., Aims: The aim of this case report is to describe the development of progressive multifocal encephalopathy in a patient with relapsing-remitting multiple sclerosis treated with ocrelizumab without previous use of natalizumab., Conclusions: A summary of the presentation and disease course is provided, presented in the context of the current literature and likely pathophysiology., (© 2023 European Academy of Neurology.)

We investigated the incidence and risk factors of seizures related to progressive multifocal leukoencephalopathy (PML) in Korean patients infected with HIV. Of the 34 patients, 14 (41.2%) developed epileptic seizures during a median follow-up of 82 months. The median time from PML diagnosis to seizure onset was 44 months, ranging from 0 to 133 months. Patients with PML who developed seizures more commonly had cognitive impairment and multiple or diffuse lesions on brain MRI. These findings highlight the increased seizure risk among HIV-infected patients with PML at any stage of the disease, particularly in cases with extensive involvement., (© 2023. The Author(s) under exclusive licence to The Journal of NeuroVirology, Inc.)

Competing Interests: None

Introduction: Progressive multifocal leukoencephalopathy (PML) is a rare, lethal, demyelinating disease classically seen in profoundly immunosuppressed individuals. It is caused by intracerebral infection by John Cunningham polyomavirus (JCV). We report a rare case of PML in a man with presumed immunocompetence at presentation experiencing bilateral painless visual impairment., Case Description: A 60-year-old man with a 3-week history of bilateral painless visual impairment attended our ophthalmology department. Unusually, he navigated around the room well and was able to read 4 of 13 Ishihara test plates in spite of a best-corrected visual acuity of counting fingers at 1 m bilaterally. Slit lamp examination, routine blood tests and optical coherence tomography (OCT) of the maculae and discs were unremarkable. Diffuse hyperintense white matter lesions on T2-weighted magnetic resonance imaging of the brain and detection of JCV within the parietal lobe tissue obtained by biopsy confirmed PML. Additional investigations identified an underlying hypogammaglobulinaemia, which may have initiated PML. He received intravenous immunoglobulin but passed away 2 months after diagnosis., Conclusions: To our knowledge this case is one of only a handful worldwide to describe PML developing in a patient with presumed immunocompetence at presentation - there was no previous history of recurrent, chronic, or atypical infections. There has only been one other report of visual symptoms presenting as the primary complaint. The case illustrates the importance of ruling out organic, central nervous system pathology in patients presenting with visual loss and normal objective visual function tests such as slit lamp examination and OCT.

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the CNS caused by the human polyomavirus 2 (JCV). PML predominantly occurs in immunocompromised patients. To date, no specific antiviral treatment exists, leaving only restoration of the immune system as possible treatment. In 2019, the monoclonal antibody pembrolizumab was reported as a potential treatment option in PML in a case series. Following case reports could not thoroughly confirm a positive outcome. Pembrolizumab targets the inhibitory programmed cell death protein 1 (PD-1) receptor on lymphocytes and is associated with beneficial expansion of pre-existing virus-specific T cells. Here we describe a patient with PML who benefited from combined treatment with intravenous immunoglobulins, maraviroc, and pembrolizumab., (© 2022. The Author(s).)

Background: Progressive multifocal leukoencephalopathy (PML) with subsequent immune reconstitution inflammatory syndrome (IRIS) is a rare disease associated with compromised immune systems. It has never been described in a patient taking tofacitinib., Case Presentation: A 49-year-old woman with history of systemic lupus erythematous treated with tofacitinib presented with several weeks of intermittent fevers and altered mental status. MRI revealed multifocal T2-weighted FLAIR hyperintensities in the subcortical white matter, including the subcortical U-fibers, without mass effect or contrast enhancement, compatible with PML. Tofacitinib was stopped and the patient's symptoms initially improved. However, the patient presented again less than a week after discharge with three days of left arm weakness, left facial droop, dysarthria, and one day of confusion. Repeat MRI demonstrated interval progression in T2/FLAIR hyperintensities with development of patchy gadolinium enhancement on T1-post contrasted sequences, consistent with development of IRIS in the setting of tofacitinib cessation., Discussion: This is the first case describing PML-IRIS in the setting of administration and subsequent cessation of tofacitinib., (Published by Elsevier B.V.)

Good's syndrome (GS) is an immunodeficiency characterized by thymoma, hypogammaglobulinemia, and impaired T-cell function. Progressive multifocal encephalopathy (PML), an infection caused by JC virus (JCV), usually occurs in patients infected with human immunodeficiency virus (HIV), or in patients on treatment with immunosuppressive or immunomodulatory drugs. There were few reports of PML due to GS, especially with the comorbidity of peripheral neuropathy. We describe a case of an uncommon presentation of PML and peripheral neuropathy in a male who presented with blurred vision, cognitive changes, limb weakness, and numbness over a 4-month period due to GS. To the best of our knowledge, this is the first report of PML and peripheral neuropathy due to GS. This case aims to highlight that it is necessary to consider the possibility of PML due to GS in patients with thymoma and intracranial lesions, and we should focus not only on opportunistic infections of the central nervous system, such as PML, but also on peripheral neuropathy., (© 2022. Journal of NeuroVirology, Inc.)

Background: Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating lytic brain infection caused by the John Cunningham virus (JCV). JCV manifests primarily in patients with innate immunodeficiency or taking immunomodulatory medications. In this case study, we report a PML patient with comorbid mediastinal teratoma and mild lymphopenia., Case Presentation: A 73-year-old female presented with a 3-month history of progressive hemiplegia, hemianopsia, and cognitive impairment. She was diagnosed as PML by cerebrospinal fluid metagenomics sequencing and brain biopsy. Extensive immunological tests did not reveal an apparent immunodeficiency, but further work-up revealed that the PML was most likely the first presentation of mediastinal teratoma and the mild lymphopenia. Mirtazapine and immunoglobulin were started, the patient's condition was relatively stable and approved to be discharged from hospital. But unfortunately, she died of the lung infection 10 months after first presentation., Conclusions: This case confirms that mediastinal teratoma may induce the lymphopenia and trigger PML, delayed or incorrect diagnosis may worsen the course of the disease and result in poor prognosis., (© 2022. The Author(s).)

Background: The search for an aetiology of central nervous system (CNS) lesions In HIV patients can be extremely challenging., Aim: To establish the nature and character of CNS lesion according to the data of pathological examination of deceased HIV-patients who had an antemortem clinical diagnosis of unspecified encephalitis., Materials and Methods: We analysed clinical and laboratory data of 225 HIV-patients admitted to the ICU at the Infectious Clinical Hospital №2 (Moscow, 2018). The principal diagnosis was unspecified encephalitis characterized by cerebral oedema. Had died 183 (67.9%) patients. We conducted pathological examination in 43 (23.5%)., Results: CNS lesions occurred in 331 patients (58.8% of 563 ICU). The antemortem diagnosis established were as follows: 12.1% toxoplasmosis; 6.6% HIV-encephalitis; 5.1% CNS lymphoma; 3.6% cryptococcal meningoencephalitis; 3.0% cytomegaloviral diseases; 2.1% progressive multifocal leukoencephalopathy. The cause of the pathology remained unidentified in 225 patients (68% with CNS lesions). Majority of patients were ART-naive. Post-mortem verification was conducted in 29 (67.4%) deceased patients, of which HIV-encephalitis 34.5%, toxoplasmosis 10.3%, progressive multifocal leukoencephalopathy 3.4%. The nature of brain damage in the remaining 20.7% cases was not established even after post-mortem investigation. Productive lepto-meningitis 8 (27.6%), indicating a prolonged duration of the inflammatory process. In the brain 48.1% patients with subacute and productive changes, had a pre-hospital time of more than 30 days, in contrast to 11.1% of patients who had acute pathological processes in the CNS (p0.05). Autopsy didnt reveal any inflammatory changes in the brain in 14 (32.6%) patients, though cerebral oedema 93.3%, haemorrhagic syndrome 60% cases., Conclusion: Accurate retrospective identification of the aetiology of CNS lesions combined with assessing in vivo characterisation of the pathological process plays an essential role in subsequent formation of diagnostic approaches in pathologies of the CNS in HIV-patients.

We present a case of a 58-year-old man with a history of severe discoid lupus erythematosus and acute encephalopathy and incoordination. Antinuclear antibody testing was weakly positive but all other laboratory tests for systemic lupus erythematosus were negative and serum quantitative immunoglobulins and lymphocytes were normal. MRI brain showed T2/FLAIR hyperintensities within the bilateral parietal and temporal lobes with involvement of subcortical U fibers. CSF PCR was negative for varicella-zoster virus, herpes simplex, JCV and BK virus. However, JCV antibody index was elevated (3.88; reference: < 0.2). Right parietal brain biopsy was consistent with JCV infection and diagnostic of progressive multifocal leukoencephalopathy (PML). To the best of our knowledge, this is the first reported case of PML in a patient with discoid lupus without other traditional risk factors for the disease and highlights the need for clinical vigilance in this patient population., (Published by Elsevier B.V.)

Progressive multifocal leukoencephalopathy can complicate the course of a patient with sarcoidosis. Here we present a rare case of a 35-year-old patient with pulmonary sarcoidosis whose course was complicated by progressive multifocal leukoencephalopathy involving the cerebellum. Neuroimaging and cerebrospinal fluid PCR played a crucial role in the diagnosis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Progressive multifocal leucoencephalopathy (PML) is a demyelinating white matter disease that most often affects immunocompromised people infected by JC virus. The diagnostic gold standard is demonstrable viral DNA or protein from histopathological tissue. However, there are few detailed descriptions of cortical grey matter involvement on neuroimaging. Here we describe the histopathological correlate of cerebral grey matter involvement and radiological accompaniment in a patient with biopsy proven PML., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Abstract: Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease caused by reactivation of John Cunningham virus affecting typically subcortical and periventricular white matter of immunocompromised hosts (human immunodeficiency virus infection, hematologic malignancies). Cerebral hemispheric white matter is most commonly affected by lytic infections, leading to progressive damage to oligodendrocytes in the central nervous system. Neuroimaging usually highlights scattered foci of white matter hypodensity not attributable to contrast enhancement or mass effect. In contrast, we present an unusual case of PML predominantly affecting cervical spinal cord and brainstem in an immunocompetent host. This is a rare subset of PML case that can occur in association with connective tissue disorders (Sjögren Syndrome in this case), systemic lupus erythematosus being the most common. Progressive multifocal leukoencephalopathy should be considered in the differential diagnosis of spinal cord or brainstem lesions, particularly in the patients with connective tissue disorders., Competing Interests: The authors report no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

A 75-year-old man diagnosed with Waldenström macroglobulinemia (WM) complained of neurological symptoms. Baseline F-FDG PET/CT showed diffusely increased radioactivity in the bone marrow and decreased FDG uptake in the right cerebellum. After rituximab-containing immunochemotherapy, the patient had clinically partial response of WM, but the cerebellar lesion was enlarged. Repeated F-FDG PET/CT was similar to the baseline. Ga-pentixafor PET/CT detected residual tumor of WM in occipital bone and cervical lymph nodes, but there was no uptake in the cerebellar lesion. Finally, John Cunningham virus-related progressive multifocal leukoencephalopathy was confirmed.

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML., (Copyright © 2020 Khoy, Mariotte, Defer, Petit, Toutirais and Le Mauff.)

Cancer is the second leading cause of mortality worldwide. The study of DNA tumor-inducing viruses and their oncoproteins as a causative agent in cancer initiation and tumor progression has greatly enhanced our understanding of cancer cell biology. The initiation of oncogenesis is a complex process. Specific gene mutations cause functional changes in the cell that ultimately result in the inability to regulate cell differentiation and proliferation effectively. The human neurotropic Polyomavirus JC (JCV) belongs to the family Polyomaviridae and it is the causative agent of progressive multifocal leukoencephalopathy (PML), which is a fatal neurodegenerative disease in an immunosuppressed state. Sero-epidemiological studies have indicated JCV infection is prevalent in the population (85%) and that initial infection usually occurs during childhood. The JC virus has small circular, double-stranded DNA that includes coding sequences for viral early and late proteins. Persistence of the virus in the brain and other tissues, as well as its potential to transform cells, has made it a subject of study for its role in brain tumor development. Earlier observation of malignant astrocytes and oligodendrocytes in PML, as well as glioblastoma formation in non-human primates inoculated with JCV, led to the hypothesis that JCV plays a role in central nervous system (CNS) tumorigenesis. Some studies have reported the presence of both JC viral DNA and its proteins in several primary brain tumor specimens. The discovery of new Polyomaviruses such as the Merkel cell Polyomavirus, which is associated with Merkel cell carcinomas in humans, ignited our interest in the role of the JC virus in CNS tumors. The current evidence known about JCV and its effects, which are sufficient to produce tumors in animal models, suggest it can be a causative factor in central nervous system tumorigenesis. However, there is no clear association between JCV presence in CNS and its ability to initiate CNS cancer and tumor formation in humans. In this review, we will discuss the correlation between JCV and tumorigenesis of CNS in animal models, and we will give an overview of the current evidence for the JC virus's role in brain tumor formation.

Objective: Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system, caused by reactivation of John Cunningham polyomavirus, affecting mainly patients in an immunocompromised state. Recently, drug-associated PML is gaining attention as more cases of PML in connection with the use of various immunomodulatory drugs emerge. Over the last couple of years, sporadic reports have occurred about a possible association between PML and the use of a new immunomodulatory drug, ibrutinib (Imbruvica), primarily indicated for the treatment of various B-cell malignancies., Case Report: Herein, we report a case of a 62-year-old female patient with bilateral mantle cell lymphoma of conjunctiva diagnosed at IVA clinical stage (according to the Ann Arbor staging of lymphomas) of the disease. As a first line of treatment, the patient was given 6 cycles of rituximab-based chemotherapy followed by a complete remission. Seven years later, the patient relapsed, at which point the treatment with ibrutinib was initiated. Three weeks after the initial dosage, the patient started to show signs of progressive neurological symptomatology and died 4 months thereafter due to bilateral bronchopneumonia. Due to unspecific MRI signs and negative PCR results, the diagnosis of PML was confirmed only postmortem., Conclusion: This case report demonstrates a possible severe adverse effect of the immunomodulatory drug ibrutinib and the importance of a multidisciplinary approach in its diagnosis. Since PML is a rare but highly fatal disease, it is of utmost importance to be aware of the possible connection with the use of this drug to prevent missed or delayed diagnosis, considering that timely therapeutic intervention is crucial for improved prognosis.

Background: Progressive multifocal leukoencephalopathy (PML) is a rare infectious cause of sub-acute neurological symptoms, and occurs predominantly in immunocompromised patients. PML is caused by reactivation of the JC virus., Case Description: A 79-year-old man with a history of chronic B-cell lymphatic leukaemia (B-CLL) presented at our hospital with a neurological deficit of the left side of his body. He was initially diagnosed with a right-hemisphere stroke. Two months later he returned with progressive paresis and on an MRI of the brain we saw an increase in abnormalities of the white matter. On suspicion of PML we conducted PCR for JC virus on cerebrospinal fluid (CSF), which was negative. Histopathological investigations of a brain biopsy confirmed the diagnosis of PML, four months after he first presented., Conclusion: PML is a rare cause of sub-acute neurological symptoms. PML can be difficult to diagnose as a PCR of CSF for JC virus in the early stages of PML can give a false negative result. If PML is suspected, histological investigation of a brain biopsy is necessary.

We present the case of a 43-year-old-man with a past medical history of HIV with recently initiated HAART and existing PML that presented with altered mental status. The initial diagnosis was deemed to be PML-IRIS; however, neuroimaging brought into question this diagnosis. Flow cytometry performed from the cerebrospinal fluid revealed diffuse large B cell lymphoma. JC virus may act in an oncogenic role similarly to EBV and predispose to CNS lymphomas. Patients with PML caused by JC virus may develop secondary malignancies.

The patient was a 74-year-old woman with rheumatoid arthritis who developed ataxia. MRI revealed T2-hyperintense lesions predominantly in the left middle cerebellar peduncle. Punctate or linear Gd enhancement was also observed on T1-weighted images. A brain biopsy was conducted and the pathology revealed a mild demyelinated lesion. Polymerase chain reaction (PCR) of biopsied brain tissues revealed the presence of JC virus (JCV) DNA, but JCV-infected oligodendroglia-like cells were not apparent on immunohistochemistry. Sensitive in-situ hybridization, however, detected three JCV-positive cells and the infiltration of CD4 + and CD8 + T cells and plasma cells was also observed. Immunosuppressants were tapered off and mirtazapine and mefloquine administered, resulting in a favorable outcome.

A case of progressive multifocal leukoencephalopathy (PML) occurring on low dose immunosuppression for systemic lupus erythematosus (SLE) and Sjogren's syndrome (SS) is presented. Neurologic changes in patients with SLE or SS should not be assumed to be a disease manifestation. Importantly, serious opportunistic infections such as PML can occur in minimally immunosuppressed rheumatic patients. Early diagnosis, facilitated by scrutiny of MRI findings, should trigger measures to reconstitute immunity in an otherwise fatal disease., (Copyright © 2019. Published by Elsevier Ltd.)

Aim: To analyse the clinical findings, complementary examinations and prognosis of patients with progressive multifocal leukoencephalopathy (PML) treated in our institution, comparing populations with and without associated human immunodeficiency virus (HIV)., Patients and Methods: A retrospective study of the medical records of patients with probable or definite PML was carried out. Clinical variables, complementary studies (cerebrospinal fluid, magnetic resonance imaging of the brain) and prognostic variables were analysed. Non-parametric statistical tests were used to compare HIV-positive and HIV non-positive populations., Results: Fourteen patients with definite and one probable diagnosis of PML were included. Nine patients had PML associated with HIV; five had other immunosuppressive conditions (two, chronic lymphatic leukaemia; one, multiple sclerosis; one, neuromyelitis optica; and one, neurosarcoidosis); and one, no obvious immunosuppressive condition. The population with HIV presented heterogeneous dirty-appearing white matter lesions more frequently (77.7% versus 16.67%; p = 0.0247) in the cerebral MRI. No other significant differences were identified in the remaining variables analysed., Conclusion: HIV/AIDS is the pathology most frequently associated with PML. With the use of immunomodulator drugs its appearance is reported in a variety of other diseases. Heterogeneous dirty-appearing white matter lesions were significantly more common in HIV patients.

Here, progressive multifocal leukoencephalopathy (PML) and PML in systemic lupus erythematosus (SLE) are reviewed. Disease-modifying therapy (DMT) associated PML is an emerging condition, particularly in multiple sclerosis patients. Although PML is a rare adverse event in SLE, we should consider development of PML more carefully in not only conventional drug-induced PML but also DMT associated PML during SLE treatment in the era of DMT associated PML.

We describe a 62-year-old man who developed subacute visual loss after cord blood stem cell transplantation for malignant lymphoma. Brain magnetic resonance imaging (MRI) showed bilateral hyperintense lesions in the occipital and parietal lobes. A diagnosis of progressive multifocal encephalopathy (PML) was established following brain biopsy and detection of JC virus (JCV) deoxyribonucleic acid (DNA) in the cerebrospinal fluid (CSF). He developed optic ataxia and visual inattention, and was then diagnosed as having Bálint syndrome. After he was treated with mefloquine and mirtazapine, his Bálint syndrome and, MRI findings improved and the copy number of JCV DNA in the CSF decreased. In summary, we demonstrate that patient with PML may develop Bálint syndrome and that combination therapy using mefloquine and mirtazapine may be an effective treatment. (Received August 23, 2018; Accepted November 29, 2018; Published March 1, 2019).

Progressive multifocal leukoencephalopathy (PML) is a rapidly progressive, often fatal viral infection of the brain without a known treatment. Recently, case reports have demonstrated survival from PML with therapies that improve cell-mediated immunity, including interleukin-7 (IL-7) or the chemokine receptor type 5 (CCR5) antagonist, maraviroc (MVC). We present the first known case of a patient with PML successfully treated with both IL-7 and MVC. A 63-year-old woman presented to our center with a 6-month history of progressive left hemiparesis. Extensive laboratory testing was negative except for a severe CD4 lymphocytopenia (140/μL). Serial brain MRIs done prior to presentation revealed an enlarging, non-enhancing T2-hyperintense lesion in the right fronto-parietal white matter. PML was confirmed through detection of the JC virus by PCR in the cerebrospinal fluid and by brain biopsy, and she was started on mirtazapine and mefloquine. She continued to deteriorate and was then given a course of recombinant IL-7. Though she remained clinically stable after IL-7 treatment and serum JCV PCR decreased from 1000 copies/mL to a nadir of 238 copies/mL, a repeat MRI 3 months later showed lesion enlargement. MVC was then initiated. Now, more than 2 years after initial presentation, she remains stable and serum JCV PCR is undetectable. This case demonstrates successful treatment of PML in a patient with idiopathic CD4 lymphocytopenia and highlights the potential benefits of IL-7 and MVC in the treatment of PML. Treatment with IL-7 and MVC led to clinical stability and improvement in JC virus titers.

Progressive multifocal leukoencephalopathy is a central nervous system demyelinating disease caused by infection with John Cunningham virus. It affects predominantly the subcortical white matter, producing progressive neurological deficits and large confluent white matter lesions on imaging. It is usually seen in immunodeficient individuals, such as those suffering from acquired immunodeficiency syndrome, those on treatment with monoclonal antibodies, and those following therapeutic bone marrow suppression. Here, we report a rare case of progressive multifocal leukoencephalopathy in an apparently immunocompetent adult, who was found to have idiopathic CD4 lymphocytopenia upon further investigation.

John Cunningham virus (JCV) causes rare, but potentially life-threatening progressive multifocal leukoencephalopathy (PML) in natalizumab-treated multiple sclerosis (MS) patients. Beside JCV index, there is currently no other factor for further risk stratification. Because smoking was reported as potential risk factor for several viral and bacterial infections, we aimed to investigate whether smoking could increase the risk for JCV infection in MS patients. We screened our database of the MS Clinic of the Department of Neurology, Medical University of Innsbruck, Austria, for patients with known smoking status and test result for anti-JCV antibody index as determined by two-step ELISA at Unilabs, Copenhagen, Denmark. In a representative cohort of 200 MS patients with a rate of 36% current smokers plus 6% former smokers, we were not able to detect any association between smoking and JCV status. Furthermore, there was no association between smoking status and anti-JCV antibody index. Smoking does not seem to be a risk factor for JCV infection in MS patients and, therefore, does not represent a suitable marker for PML-risk stratification under treatment with natalizumab.

Background and Objective: Natalizumab-associated progressive multifocal leukoencephalopathy (NTZ-PML) patients may show imaging signs suggestive of inflammation at diagnosis ('inflammatory PML'), reminiscent of PML-immune reconstitution inflammatory syndrome (PML-IRIS). We investigated the imaging characteristics of inflammatory NTZ-PML lesions and PML-IRIS to determine differentiating and overlapping features., Methods: We scored the presence, localisation and pattern of imaging characteristics of inflammation on brain MRI scans of inflammatory NTZ-PML patients. The imaging characteristics were followed up until the occurrence of PML-IRIS., Results: Ten out of the 44 NTZ-PML patients included showed signs suggestive of inflammation at the time of diagnosis. The inflammation pattern at diagnosis was similar to the pattern seen at PML-IRIS, with contrast enhancement representing the most frequent sign of inflammation (90% at diagnosis, 100% at PML-IRIS). However, the severity of inflammation differed, with absence of swelling and low frequency of perilesional oedema (10%) at diagnosis, as compared with the PML-IRIS stage (40%)., Conclusion: Patterns of inflammation at the time of PML diagnosis and at the PML-IRIS stage overlap but differ in their severity of inflammation. This supports histopathological evidence that the inflammation seen at both stages of the same disease shares a similar underlying pathophysiology, representing the immune response to the JC virus to a variable extend., Competing Interests: Competing interests: MPW has received consultancy fees from Biogen, Novartis and Roche. FB serves as a consultant for Bayer-Schering Pharma, Sanofi-Aventis, Biogen, Teva, Novartis, Roche, Synthon BV, Genzyme and Jansen Research. JK has accepted consulting fees from Merck-Serono, TEVA, Biogen, Genzyme and Novartis. BMJU has received consultancy fees from Novartis, Merck Serono, Biogen and Danone Research. MTW does not report any competing interest. The VUmc has received financial support for research activities from Bayer Schering Pharma, Biogen, Glaxo Smith Kline, Merck Serono, Novartis and Teva. JE received consultancy fees and/or lecture fees from Biogen, Genzyme, Teva, Merck and Novartis. The authors had full editorial control of the manuscript and provided their final approval of all content., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)