Inflammatory natalizumab-associated PML: baseline characteristics, lesion evolution and relation with PML-IRIS

Atypical Demyelinating Disorders: MR Imaging Features, Atypical Triggers, and Etiopathogenesis

Atypical demyelinating lesions (ADLs) can be idiopathic, occurring as isolated and self-limited events, or can appear in different stages of relapsing demyelinating diseases. Not infrequently, ADLs occur in inflammatory syndromes associated with exogenous or endogenous toxic factors, metabolic imbalance, or infectious agents. It is important to recognize imaging patterns that indicate an inflammatory/demyelinating substrate in central nervous system lesions and to investigate potential triggers or complicating factors that might be associated. The prognostic and treatment strategies of ADLs are influenced by the underlying etiopathogenesis.

Routine MR Imaging Protocol and Standardization in Central Nervous System Demyelinating Diseases

Standardized MR imaging protocols are important for the diagnosis and monitoring of patients with multiple sclerosis (MS) and the appropriate use of MR imaging in routine clinical practice. Advances in using MR imaging to establish an earlier diagnosis of MS, safety concerns regarding intravenous gadolinium-based contrast agents, and the value of spinal cord MR imaging for diagnostic, prognostic, and monitoring purposes suggest a changing role of MR imaging for the management and care of MS patients. The MR imaging protocol emphasizes 3 dimensional acquisitions for optimal comparison over time.

John Cunningham Virus and Progressive Multifocal Leukoencephalopathy: A Falsely Played Diagnosis

Progressive Multifocal Leukoencephalopathy (PML) is a possibly fatal demyelinating disease and John Cunningham Polyomavirus (JCPyV) is believed to cause this condition. The so-called JCPyV was initially reported in lymphoma and Human Immunodeficiency Virus (HIV) cases, whereas nowadays, its incidence is increasing in Multiple Sclerosis (MS) cases treated with natalizumab (Tysabri). However, there are conflicting literature data on its pathology and diagnosis, whereas some misdiagnosed reports exist, giving rise to further questions towards the topic. In reality, the so-called PML and the supposed JCPyV are not what they seem to be. In addition, novel and more frequent PML-like conditions may be reported, especially after the Coronavirus Disease 2019 (COVID-19) pandemic.

Pathology for severe inflammatory PML with PD1/PD-L1 expression of favorable prognosis: What's a prognostic factor for PML-IRIS?

A 72-year-old woman with dermatomyositis (DM) developed neurological manifestation, and magnetic resonance imaging (MRI) revealed multiple T2/fluid-attenuated inversion recovery (FLAIR)-hyperintense lesions predominantly in the deep white matter of the cerebral hemisphere. Punctate or linear contrast enhancement was observed surrounding the T1-hypointense area. Multiple T2/FLAIR-hyperintense lesions were aligned along with the corona radiata. Malignant lymphoma was first suspected, and a brain biopsy was performed. Pathological investigation suggested the provisional diagnosis of "suspicious of malignant lymphoma." Owing to emergent clinical conditions, high-dose methotrexate (MTX) therapy was conducted, and then T2/FLAIR-hyperintense lesions were dramatically reduced. However, the diagnosis of malignant lymphoma was concerning since multiplex PCR demonstrated clonal restriction of the Ig H gene for B cells and TCR beta genes for T cells. Histopathology revealed the infiltration of both CD4+ and CD8+ T cells, and the CD4+ /CD8+ ratio was 4.0. Moreover, prominent plasma cells were observed, in addition to CD20+ B cells. Atypical cells with enlarged nuclei were present, and they were not hematopoietic but found as glial cells. JC virus (JCV) infection was verified with both immunohistochemistry and in situ hybridization; the final diagnosis was progressive multifocal leukoencephalopathy (PML). The patient was treated with mefloquine and discharged. This case is informative in understanding the host anti-viral response. Variable inflammatory cells were observed, including CD4+ and CD8+ T cells, plasma cells, and a small amount of perivascular CD20+ B cells. PD-1 and PD-L1 expression was observed in lymphoid cells and macrophages, respectively. PML with inflammatory reactions was thought fatal, and autopsy cases of PML with immune reconstitution inflammatory syndrome (IRIS) demonstrated excessive infiltration of only CD8+ T cells. However, this case revealed infiltration of variable inflammatory cells, and a favorable prognosis would be expected under PD-1/PD-L1 immune-checkpoint regulation.

[Use of Gadolinium in Follow-Up MRI of Multiple Sclerosis Patients: Current Recommendations]

Multiple sclerosis is the most frequent demyelinating disease of the central nervous system and is characterized by early onset and progressive disability. Magnetic resonance imaging, due to its high sensitivity and specificity in the detection of demyelinating lesions, is the most useful diagnostic test for this disease, with the administration of gadolinium-based contrast agents being an important contribution to imaging interpretation. Although contrast is essential for diagnostic purposes, its routine use in monitoring disease activity, response to treatment, and related complications is controversial. This article aims to collate current recommendations regarding the use of gadolinium in the imaging follow-up of multiple sclerosis and establish effective and safe guidelines for clinical practice. The literature review was conducted in PubMed, using the terms 'multiple sclerosis', 'magnetic resonance imaging' and 'gadolinium', or 'contrast media'. Articles published between January 2013 and January 2023 concerning the safety of gadolinium and the use of these contrast agents in follow-up scans of adult patients diagnosed with multiple sclerosis were selected. Although no biological or clinical consequences have been unequivocally attributed to the retention of gadolinium in the brain, which were mostly reported with linear agents, health authorities have been recommending the restriction of contrast to essential clinical circumstances. In multiple sclerosis, the detection of subclinical contrast-enhancing lesions with no corresponding new/ enlarging T2-WI lesions is rare and has a questionable impact on therapeutic decisions. On the other hand, gadolinium has a higher sensitivity in the differential diagnosis of relapses, in the detection of recent disease activity, before and after treatment initiation, and in patients with a large lesion burden or diffuse/confluent T2-WI lesions. Contrary to progressive multifocal leukoencephalopathy screening, monitoring of immune restitution inflammatory syndrome also benefits from the administration of gadolinium. It is feasible and safe to exclude gadolinium-based contrast agents from routine follow-up scans of multiple sclerosis, despite their additional contribution in specific clinical circumstances that should be acknowledged by the neurologist and neuroradiologist.

Multiple faces of multiple sclerosis in the era of highly efficient treatment modalities: Lymphopenia and switching treatment options challenges daily practice

The expanded treatment landscape in relapsing-remitting multiple sclerosis (MS) has resulted in highly effective treatment options and complexity in managing disease- or drug-related events during disease progression. Proper decision-making requires thorough knowledge of the immunobiology of MS itself and an understanding of the main principles behind the mechanisms that lead to secondary autoimmunity affecting organs other than the central nervous system as well as opportunistic infections. The immune system is highly adapted to both environmental and disease-modifying agents. Immune reconstitution following cell depletion or cell entrapment therapies eliminates pathogenic aspects of the disease but can also lead to distorted immune responses with harmful effects. Atypical relapses occur with second-line treatments or after their discontinuation and require appropriate clinical decisions. Lymphopenia is a result of the mechanism of action of many drugs used to treat MS. However, persistent lymphopenia and cell-specific lymphopenia could result in disease exacerbation, secondary autoimmunity, or the emergence of opportunistic infections. Clinicians treating patients with MS should be aware of the multiple faces of MS under novel, efficient treatment modalities and understand the intricate brain-immune cell interactions in the context of an altered immune system. MS relapses and disease progression still occur despite the current treatment modalities and are mediated either by failure to control effector mechanisms inherent to MS pathophysiology or by new drug-related mechanisms. The multiple faces of MS due to the highly adapted immune system of patients impose the need for appropriate switching therapies that safeguard disease remission and further clinical improvement.

A Case of Primary Central Nervous System Lymphoma That Developed in a Patient Receiving Fingolimod Therapy for Multiple Sclerosis

Fingolimod is an oral medication for the prevention of multiple sclerosis relapse, and its efficacy has been demonstrated in several clinical trials. Fingolimod has various side effects, such as arrhythmia and hepatic dysfunction. In addition, there have been rare reports of the development of lymphoproliferative disorders in patients undergoing fingolimod therapy, including primary central nervous system lymphoma (PCNSL). We diagnosed and treated a multiple sclerosis patient who developed PCNSL while undergoing fingolimod therapy. Fourteen months after starting fingolimod therapy, the patient developed aphasia, and underwent biopsy analysis for a lesion displaying a homogeneous gadolinium-enhanced lesion in the left frontal lobe. The lesion was diagnosed as diffuse large B-cell lymphoma by pathological examination. After the diagnosis, the patient received chemotherapy together with methotrexate combination therapy, and the lesion became smaller and the patient's symptoms improved. Although several autopsy cases of PCNSL in patients who received fingolimod therapy have been reported, there have been few reports to date of patients diagnosed by biopsy analysis.

Progressive Multifocal Leukoencephalopathy: Pathogenesis, Diagnostic Tools, and Potential Biomarkers of Response to Therapy

JC polyomavirus (JCV) establishes an asymptomatic latent and/or persistent infection in most of the adult population. However, in immunocompromised individuals, JCV can cause a symptomatic infection of the brain, foremost progressive multifocal leukoencephalopathy (PML). In the past 2 decades, there has been increasing concern among patients and the medical community because PML was observed as an adverse event in individuals treated with modern (selective) immune suppressive treatments for various immune-mediated diseases, especially multiple sclerosis. It became evident that this devastating complication also needs to be considered beyond the patient populations historically at risk, including those with hematologic malignancies or HIV-infected individuals. We review the clinical presentation of PML, its variants, pathogenesis, and current diagnostic approaches. We further discuss the need to validate JCV-directed interventions and highlight current management strategies based on early diagnosis and restoring JCV-specific cellular immunity, which is crucial for viral clearance and survival. Finally, we discuss the importance of biomarkers for diagnosis and response to therapy, instrumental in defining sensitive study end points for successful clinical trials of curative or preventive therapeutics. Advances in understanding PML pathophysiology, host and viral genetics, and diagnostics in conjunction with novel immunotherapeutic approaches indicate that the time is right to design and perform definitive trials to develop preventive options and curative therapy for JCV-associated diseases.

Progressive multifocal leukoencephalopathy in a patient with relapsing multiple sclerosis treated with ocrelizumab: A case report

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.

Radiological abnormalities in progressive multifocal leukoencephalopathy: Identifying typical and atypical imaging patterns for early diagnosis and differential considerations

Progressive multifocal leukoencephalopathy (PML) is a rare viral central nervous system (CNS) demyelinating disease primarily associated with a compromised immune system. PML is seen mainly in individuals with human immunodeficiency virus, lymphoproliferative disease, and multiple sclerosis. Patients on immunomodulators, chemotherapy, and solid organ or bone marrow transplants are predisposed to PML. Recognition of various PML-associated typical and atypical imaging abnormalities is critical for early diagnosis and differentiating it from other conditions, especially in high-risk populations. Early PML recognition should expedite efforts at immune-system restoration, allowing for a favorable outcome. This review aims to provide a practical overview of radiological abnormalities in PML patients and address differential considerations.

Treatment with an antigen-specific dual microparticle system reverses advanced multiple sclerosis in mice

Antigen-specific therapies hold promise for treating autoimmune diseases such as multiple sclerosis while avoiding the deleterious side effects of systemic immune suppression due to delivering the disease-specific antigen as part of the treatment. In this study, an antigen-specific dual-sized microparticle (dMP) treatment reversed hind limb paralysis when administered in mice with advanced experimental autoimmune encephalomyelitis (EAE). Treatment reduced central nervous system (CNS) immune cell infiltration, demyelination, and inflammatory cytokine levels. Mechanistic insights using single-cell RNA sequencing showed that treatment impacted the MHC II antigen presentation pathway in dendritic cells, macrophages, B cells, and microglia, not only in the draining lymph nodes but also strikingly in the spinal cord. CD74 and cathepsin S were among the common genes down-regulated in most antigen presenting cell (APC) clusters, with B cells also having numerous MHC II genes reduced. Efficacy of the treatment diminished when B cells were absent, suggesting their impact in this therapy, in concert with other immune populations. Activation and inflammation were reduced in both APCs and T cells. This promising antigen-specific therapeutic approach advantageously engaged essential components of both innate and adaptive autoimmune responses and capably reversed paralysis in advanced EAE without the use of a broad immunosuppressant.

Pembrolizumab treatment of inflammatory progressive multifocal leukoencephalopathy: a report of two cases

Progressive multifocal leukoencephalopathy (PML) is a rare but devastating neurological disease caused by reactivation of the JC virus in susceptible individuals. The illness has classically been associated with the human immunodeficiency virus (HIV) and multiple sclerosis (MS) patients who are treated with natalizumab. It is also associated with haematological malignancies, organ transplantation, autoimmune disease and immunodeficiency. Aside from natalizumab, a range of other immunomodulators including obinutuzumab and rituximab have been associated with PML. The nature of these associations is unclear due to the overall low incidence of PML associated with these drugs and the fact that most patients will have other confounding risk factors for developing the disease. There is no known effective treatment available for PML in the non-HIV, non-MS cohort. Recent case studies and series have proposed that pembrolizumab, an anti-PD-1 immune checkpoint inhibitor, may be a potentially efficacious option for these patients. We present two cases of non-HIV, non-MS patients with PML who were treated with pembrolizumab with little clinical benefit. The literature surrounding pembrolizumab use in PML is discussed, with a focus on potential indicators of successful outcomes for patients who receive this therapy.

The neuroradiology of progressive multifocal leukoencephalopathy: a clinical trial perspective

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system caused by the JC virus, which infects white and grey matter cells and leads to irreversible demyelination and neuroaxonal damage. Brain magnetic resonance imaging (MRI), in addition to the clinical presentation and demonstration of JC virus DNA either in the CSF or by histopathology, is an important tool in the detection of PML. In clinical practice, standard MRI pulse sequences are utilized for screening, diagnosis, and monitoring of PML, but validated imaging-based outcome measures for use in prospective, interventional clinical trials for PML have yet to be established. We review the existing literature regarding the use of MRI and positron emission tomography imaging in PML and discuss the implications of PML histopathology for neuroradiology. MRI not only demonstrates the localization and extent of PML lesions, but also mirrors the tissue destruction, ongoing viral spread, and resulting inflammation. Finally, we explore the potential for imaging measures to serve as an outcome in PML clinical trials and provide recommendations for current and future imaging outcome measure development in this area.

CCR5 Blockade in Inflammatory PML and PML-IRIS Associated With Chronic Inflammatory Diseases' Treatments

Background and Objectives

Progressive multifocal leukoencephalopathy (PML) is a disabling neurologic disorder resulting from the infection of the CNS by JC polyomavirus in immunocompromised individuals. For the last 2 decades, increasing use of immunotherapies leads to iatrogenic PML. Iatrogenic PML is often associated with signs of inflammation at onset (inflammatory PML) and/or after treatment withdrawal immune reconstitution inflammatory syndrome (PML-IRIS). Although immune reconstitution is a key element for viral clearance, it may also be harmful and induce clinical worsening. A C-C chemokine receptor type 5 (CCR5) antagonist (maraviroc) has been proposed to prevent and/or limit the deleterious immune responses underlying PML-IRIS. However, the data to support its use remain scarce and disputed.

Methods

We conducted a multicenter retrospective cohort study at 8 university hospitals in France and Switzerland by collecting clinical, biological, and radiologic data of patients who developed inflammatory PML (iPML) or PML-IRIS related to immunosuppressive therapies used for chronic inflammatory diseases between 2010 and 2020. We added to this cohort, a meta-analysis of individual case reports of patients with iPML/PML-IRIS treated with maraviroc published up to 2021.

Results

Overall, 27 cases were identified in the cohort and 9 from the literature. Among them, 27 met the inclusion criteria: 16 treated with maraviroc and 11 with standard of care (including corticosteroids use). Most cases were related to MS (92.6%) and natalizumab (88%). Inflammatory features (iPML) were present at onset in 12 patients (44.4%), and most patients (92.6%) received corticosteroids within the course of PML. Aggravation due to PML-IRIS was not prevented by maraviroc compared with patients who received only corticosteroids (adjusted odds ratio: 0.408, 95% CI: 0.06–2.63). Similarly, maraviroc did not influence time to clinical worsening due to PML-IRIS (adjusted hazard ratio = 0.529, 95% CI: 0.14–2.0) or disability at the last follow-up (adjusted odds ratio: 2, 95% CI: 0.23–17.3).

Discussion

The use of CCR5 blockade did not help to keep deleterious immune reconstitution in check even when associated with corticosteroids. Despite maraviroc's reassuring safety profile, this study does not support its use in iPML/PML-IRIS.

Classification of Evidence

This study provides Class IV evidence showing that adding maraviroc to the management of iatrogenic iPML/PML-IRIS does not improve the outcome.

Immune profile and radiological characteristics of progressive multifocal leukoencephalopathy

BACKGROUND AND PURPOSE

Progressive multifocal leukoencephalopathy (PML) constitutes a severe disease with increasing incidence, mostly in the context of immunosuppressive therapies. A detailed understanding of immune response in PML appears critical for the treatment strategy. The aim was a comprehensive immunoprofiling and radiological characterization of magnetic resonance imaging (MRI) defined PML variants.

METHODS

All biopsy-confirmed PML patients (n = 15) treated in our department between January 2004 and July 2019 were retrospectively analysed. Data from MRI, histology as well as detailed clinical and outcome data were collected. The MRI-defined variants of classical (cPML) and inflammatory (iPML) PML were discriminated based on the intensity of gadolinium enhancement. In these PML variants, intensity and localization (perivascular vs. parenchymal) of inflammation in MRI and histology as well as the cellular composition by immunohistochemistry were assessed. The size of the demyelinating lesions was correlated with immune cell infiltration.

RESULTS

Patients with MRI-defined iPML showed a stronger intensity of inflammation with an increased lymphocyte infiltration on histological level. Also, iPML was characterized by a predominantly perivascular inflammation. However, cPML patients also demonstrated certain inflammatory tissue alterations. Infiltration of CD163-positive microglia and macrophage (M/M) subtypes correlated with PML lesion size.

CONCLUSIONS

The non-invasive MRI-based discrimination of PML variants allows for an estimation of inflammatory tissue alterations, although exhibiting limitations in MRI-defined cPML. The association of a distinct phagocytic M/M subtype with the extent of demyelination might reflect disease progression.

2021 MAGNIMS-CMSC-NAIMS consensus recommendations on the use of MRI in patients with multiple sclerosis

The 2015 Magnetic Resonance Imaging in Multiple Sclerosis and 2016 Consortium of Multiple Sclerosis Centres guidelines on the use of MRI in diagnosis and monitoring of multiple sclerosis made an important step towards appropriate use of MRI in routine clinical practice. Since their promulgation, there have been substantial relevant advances in knowledge, including the 2017 revisions of the McDonald diagnostic criteria, renewed safety concerns regarding intravenous gadolinium-based contrast agents, and the value of spinal cord MRI for diagnostic, prognostic, and monitoring purposes. These developments suggest a changing role of MRI for the management of patients with multiple sclerosis. This 2021 revision of the previous guidelines on MRI use for patients with multiple sclerosis merges recommendations from the Magnetic Resonance Imaging in Multiple Sclerosis study group, Consortium of Multiple Sclerosis Centres, and North American Imaging in Multiple Sclerosis Cooperative, and translates research findings into clinical practice to improve the use of MRI for diagnosis, prognosis, and monitoring of individuals with multiple sclerosis. We recommend changes in MRI acquisition protocols, such as emphasising the value of three dimensional-fluid-attenuated inversion recovery as the core brain pulse sequence to improve diagnostic accuracy and ability to identify new lesions to monitor treatment effectiveness, and we provide recommendations for the judicious use of gadolinium-based contrast agents for specific clinical purposes. Additionally, we extend the recommendations to the use of MRI in patients with multiple sclerosis in childhood, during pregnancy, and in the post-partum period. Finally, we discuss promising MRI approaches that might deserve introduction into clinical practice in the near future.

Intracranial Abnormalities with Diffusion Restriction

Multiple pathologic conditions can cause changes in the random movement of water, which can be detected with diffusion-weighted imaging (DWI). DWI plays a powerful clinical role in detecting restricted diffusion associated with acute brain infarction. Other disorders can also result in restricted diffusion. This article focuses on showing examples of common and uncommon disorders that have restricted diffusion secondary to cytotoxic and/or intramyelinic edema. These disorders include ischemia, infection, noninfectious demyelinating diseases, genetic mutations affecting metabolism, acquired metabolic disorders, toxic or drug exposures, neoplasms and tumorlike lesions, radiation treatment, trauma, and denervation.

The Effect of Intravenous Methylprednisolone on Recurrent Exacerbation in Hematologic Malignancy-associated Progressive Multifocal Leukoencephalopathy

We herein report a 65-year-old man with progressive multifocal leukoencephalopathy (PML) after 2-year remission from acute myeloid leukemia who developed recurrent episodes of left hemiparesis with gadolinium enhancement on magnetic resonance imaging. Steroid pulse therapy for each exacerbation induced clinical and radiological improvement, suggesting that exacerbations are an excessive immune response to the JC virus and distinct from immune reconstitution inflammatory syndrome (IRIS). Although glucocorticoids are recommended only for IRIS, steroid pulse therapy should be considered as a therapeutic option in cases of exacerbation of hematologic malignancy-associated PML. Importantly, neuroimaging is not sufficient to differentiate excessive inflammation from a controlled inflammatory response, for which steroids are not recommended.

Case Report: Central Nervous System Immune Reconstitution Inflammatory Syndrome Related to Bacterial Meningitis

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) describes clinical characteristics that may be observed in previously immunocompromised patients during rapid restoration of immunity function in the presence of a pathogen. There have been no reports about CNS-IRIS related to bacterial meningitis so far. Here, we report a 24-year-old pregnant female patient with bacterial meningitis. Her clinical and neuroradiological condition worsened after induced labor despite great effective anti-infective therapy. CNS-IRIS was considered. Corticosteroids were administered, and the patient gradually recovered. We present the first case of CNS-IRIS associated with bacterial meningitis.

Clinical Presentation and Disease Course of 37 Consecutive Cases of Progressive Multifocal Leukoencephalopathy (PML) at a German Tertiary-Care Hospital: A Retrospective Observational Study

Background: Progressive multifocal leukoencephalopathy (PML) caused by JCV is a rare but frequently fatal disease of the central nervous system, usually affecting immunocompromised individuals. Our study aims to expand the data on patient characteristics, diagnosis, clinical course, possible PML-directed treatment, and outcome of patients with PML at a German tertiary-care hospital. Methods:In this single-center observational cohort study, 37 consecutive patients with a confirmed diagnosis of PML seen at the University Medical Center Hamburg-Eppendorf from 2013 until 2019 were retrospectively analyzed by chart review with a special focus on demographics, risk factors, and clinical aspects as well as PML-directed treatment and survival. Results:We identified 37 patients with definite, probable, and possible PML diagnosis. 36 patients (97%) had underlying immunosuppressive disorders such as HIV/AIDS (n = 17; 46%), previous treatment with monoclonal antibodies (n = 6; 16%), hematological or oncological malignancies (n = 6; 16%), sarcoidosis (n = 5; 14%), solid organ transplantation (n = 1; 3%), and diagnosis of mixed connective tissue disease (n = 1; 3%). In only one patient no evident immunocompromised condition was detected (n = 1; 3%). Treatment attempts to improve the outcome of PML were reported in 13 patients (n = 13; 35%). Twenty seven percent of patients were lost to follow-up (n = 10). Twenty four-month survival rate after diagnosis of PML was 56% (n = 15). Conclusion: This interdisciplinary retrospective study describes epidemiology, risk factors, clinical course, and treatment trials in patients with PML at a German tertiary-care hospital. Acquired immunosuppression due to HIV-1 constituted the leading cause of PML in this monocenter cohort.

Pharmacovigilance during treatment of multiple sclerosis: early recognition of CNS complications

An increasing number of highly effective disease-modifying therapies for people with multiple sclerosis (MS) have recently gained marketing approval. While the beneficial effects of these drugs in terms of clinical and imaging outcome measures is welcomed, these therapeutics are associated with substance-specific or group-specific adverse events that include severe and fatal complications. These adverse events comprise both infectious and non-infectious complications that can occur within, or outside of the central nervous system (CNS). Awareness and risk assessment strategies thus require interdisciplinary management, and robust clinical and paraclinical surveillance strategies. In this review, we discuss the current role of MRI in safety monitoring during pharmacovigilance of patients treated with (selective) immune suppressive therapies for MS. MRI, particularly brain MRI, has a pivotal role in the early diagnosis of CNS complications that potentially are severely debilitating and may even be lethal. Early recognition of such CNS complications may improve functional outcome and survival, and thus knowledge on MRI features of treatment-associated complications is of paramount importance to MS clinicians, but also of relevance to general neurologists and radiologists.

Progressive multifocal leukoencephalopathy: MRI findings in HIV-infected patients are closer to rituximab- than natalizumab-associated PML

Objectives

To compare brain MRI findings in progressive multifocal leukoencephalopathy (PML) associated to rituximab and natalizumab treatments and HIV infection.

Materials and methods

In this retrospective, multicentric study, we analyzed brain MRI exams from 72 patients diagnosed with definite PML: 32 after natalizumab treatment, 20 after rituximab treatment, and 20 HIV patients. We compared T2- or FLAIR-weighted images, diffusion-weighted images, T2*-weighted images, and contrast enhancement features, as well as lesion distribution, especially gray matter involvement.

Results

The three PML entities affect U-fibers associated with low signal intensities on T2*-weighted sequences. Natalizumab-associated PML showed a punctuate microcystic appearance in or in the vicinity of the main PML lesions, a potential involvement of the cortex, and contrast enhancement. HIV and rituximab-associated PML showed only mild contrast enhancement, punctuate appearance, and cortical involvement. The CD4/CD8 ratio showed a trend to be higher in the natalizumab group, possibly mirroring a more efficient immune response.

Conclusion

Imaging features of rituximab-associated PML are different from those of natalizumab-associated PML and are closer to those observed in HIV-associated PML.

Key Points

• Nowadays, PML is emerging as a complication of new effective therapies based on monoclonal antibodies.

• Natalizumab-associated PML shows more inflammatory signs, a perivascular distribution “the milky way,” and more cortex involvement than rituximab- and HIV-associated PML.

• MRI differences are probably related to higher levels of immunosuppression in HIV patients and those under rituximab therapy.

Fifty Years of JC Polyomavirus: A Brief Overview and Remaining Questions

In the fifty years since the discovery of JC polyomavirus (JCPyV), the body of research representing our collective knowledge on this virus has grown substantially. As the causative agent of progressive multifocal leukoencephalopathy (PML), an often fatal central nervous system disease, JCPyV remains enigmatic in its ability to live a dual lifestyle. In most individuals, JCPyV reproduces benignly in renal tissues, but in a subset of immunocompromised individuals, JCPyV undergoes rearrangement and begins lytic infection of the central nervous system, subsequently becoming highly debilitating-and in many cases, deadly. Understanding the mechanisms allowing this process to occur is vital to the development of new and more effective diagnosis and treatment options for those at risk of developing PML. Here, we discuss the current state of affairs with regards to JCPyV and PML; first summarizing the history of PML as a disease and then discussing current treatment options and the viral biology of JCPyV as we understand it. We highlight the foundational research published in recent years on PML and JCPyV and attempt to outline which next steps are most necessary to reduce the disease burden of PML in populations at risk.

Neuroimaging Insights Into Early Stages of HIV-Progressive Multifocal Leukoencephalopathy: A Case Report

This report aims to enhance the understanding of early longitudinal neuroimaging features of progressive multifocal leukoencephalopathy (PML) in human immunodeficiency virus (HIV). Neuroimaging has become crucial in the diagnosis and early recognition of PML. Recognition of magnetic resonance imaging (MRI) features in the early stages of PML is paramount to avoid misdiagnosis and facilitate the delivery of treatments aimed at reducing disease progression. A 49-year-old white man with HIV presented with 4-month progressive left-sided weakness. Neurological examination revealed mild cognitive impairment, left-sided hemiparesis, and somatosense impairment to all modalities. Brain MRI revealed a punctate pattern with innumerable T2-FLAIR (fluid attenuated inversion recovery) hyperintensities in the cortex, brainstem, cerebellum, subcortical, and periventricular areas. Susceptibility-weighted imaging (SWI) revealed hypointensities involving subcortical U-fibers and cortical architecture. A comprehensive diagnostic evaluation was inconclusive. John Cunningham virus (JCV) PCR in cerebrospinal fluid (CSF) was indeterminate. He was started on antiretroviral therapy. Repeat brain MRI performed 1.5 months later, in the setting of further neurological decline, demonstrated progression of the T2-hyperintensities into a large confluent white matter lesion in the right frontoparietal lobe. Despite an indeterminate JCV PCR, the appearance and characteristic progression of the lesions in successive imaging in the setting of severe immunosuppression, with extensive negative infectious workup, was indicative of PML. This clinical experience illustrates unique neuroimaging features of HIV-PML in early stages and its progression over time. It especially highlights the relevance of the SWI sequence in the diagnosis and features observed with disease evolution. Short-term imaging follow-up may assist with the recognition of MRI features consistent with the biology of the infection.

Probable progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome with immunosuppressant dose reduction following lung transplantation: a case report and literature review

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a rapidly developing demyelinating disease in the cerebral white matter and is often caused by JC polyomavirus (JCV). PML after lung transplantation is rare and has a poor prognosis, with no established therapies. Reducing the patient's immunosuppressant doses, thereby restoring immunity, could be used to treat PML. However, some patients develop immune reconstitution inflammatory syndrome (IRIS) with this treatment, an immune-induced inflammatory response to JCV that results in serious neuronal damage. We herein report a case of a 60-year-old female who suffered from PML 5 years after lung transplantation, had worsened brain lesions thought to be related to PML-IRIS at the time of immunosuppressant reduction, and missed treatment opportunities.

CASE PRESENTATION

A 60-year-old female developed PML 5 years after lung transplantation. Fluid-attenuated inversion recovery and diffusion-weighted brain magnetic resonance imaging (MRI) revealed multiple high-signal lesions, mainly in the cerebral white matter. Polymerase chain reaction found 0.32 million copies/mL of JCV in the cerebrospinal fluid. Thus, she was given a diagnosis of PML. Mycophenolate mofetil and tacrolimus dosages were reduced, and CD4-positive cell counts and the blood concentration of each immunosuppressant were monitored. Mefloquine was also orally administered at a daily dose of 275 mg for 3 days and was then administered at a dose of 275 mg per week. Although the patient's CD4-positive cell counts increased and her immune system recovered, her symptoms and brain MRI findings worsened. We suspected PML progression or a transition to PML-IRIS. Steroid pulse therapy to suppress the inflammatory lesions was not possible but was retrospectively indicated. The patient rapidly began to exhibit akinetic mutism and died 4 months after the onset of neurologic symptoms.

CONCLUSIONS

When neurologic symptoms and abnormal brain MRI findings are noted during immune recovery, it is often difficult to distinguish between progressed PML and PML-IRIS. However, the pathogenesis of brain lesions usually involves inflammation and immune-reactive mechanisms for JCV. Steroid pulse therapy, which can reduce inflammation, should thus be administered in organ transplantation cases with differential diagnoses including PML-IRIS.

Susceptibility-Weighted MR Imaging Hypointense Rim in Progressive Multifocal Leukoencephalopathy: The End Point of Neuroinflammation and a Potential Outcome Predictor

BACKGROUND AND PURPOSE

Progressive multifocal leukoencephalopathy (PML) represents a life-threatening demyelinating disorder of the brain caused by reactivation of a rare opportunistic infection with JC Polyomavirus. The aims of this study were to describe the incidence of a susceptibility-weighted imaging hypointense rim in patients with multifocal leukoencephalopathy and to explore the histologic correlates and prognostic value of the rim with regard to the clinical outcome.

MATERIALS AND METHODS

This retrospective study included 18 patients with a definite diagnosis of progressive multifocal leukoencephalopathy. Ten patients were HIV-positive, 3 patients had natalizumab-associated progressive multifocal leukoencephalopathy, 1 patient had multiple myeloma, 3 patients had a history of lymphoma, and 1 was diagnosed with acute myeloid leukemia. Patients were divided into short- (up to 12 months) and long-term (>12 months) survivors. A total of 93 initial and follow-up MR imaging examinations were reviewed. On SWI, the presence and development of a hypointense rim at the periphery of the progressive multifocal leukoencephalopathy lesions were noted. A postmortem histologic examination was performed in 2 patients: A rim formed in one, and in one, there was no rim.

RESULTS

A total of 73 progressive multifocal leukoencephalopathy lesions were observed. In 13 (72.2%) patients, a well-defined thin, linear, hypointense rim at the periphery of the lesion toward the cortical side was present, while in 5 (27.8%) patients, it was completely absent. All 11 long-term survivors and 2 short-term survivors presented with a prominent SWI-hypointense rim, while 5/7 short-term survivors did not have this rim.

CONCLUSIONS

The thin, uniformly linear, gyriform SWI-hypointense rim in the paralesional U-fibers in patients with definite progressive multifocal leukoencephalopathy might represent an end-point stage of the neuroinflammatory process in long-term survivors.

Treatment of natalizumab-associated PML with filgrastim

Objective

There is no consensus on the treatment of progressive multifocal leukoencephalopathy (PML) occurring in multiple sclerosis (MS) patients treated with natalizumab (Nz). We report novel immune activating treatment with filgrastim of Nz‐associated PML in MS patients treated at Rush University Medical Center.

Methods

We retrospectively analyzed 17 Nz‐PML patients treated at this single tertiary referral center between 2010 and 2017. We reviewed the clinical symptoms, diagnostic methods, survival, outcome and MS modifying therapy (MSMT) after Nz‐PML.

Results

PML occurred after an average of 49 Nz infusions. To facilitate JCV elimination by accelerating immune reconstitution inflammatory syndrome (IRIS), all patients received subcutaneous filgrastim upon PML diagnosis and discontinuation of Nz; eight received plasma exchange (PLEX). Earlier than previously published, PML‐IRIS occurred in 15 of 17 (88.2%) patients within a mean of 57.4 days (SD 21.20) after the last Nz infusion. Seven patients recovered to or near baseline. There were no PML/IRIS–related fatalities but one patient committed suicide 2.5 years later. PLEX had no impact on PML outcome. Of 17 patients, 3 (18%) had MS relapses within 1 year after PML, and 5 (29%) beyond 1 year of PML onset, which is lower than expected in highly active MS patients. Eight patients started MSMTs after Nz‐PML on an average of 26 months after Nz withdrawal.

Interpretation

Our findings indicate that immunoactivation with filgrastim during PML and careful management of subsequent IRIS is likely beneficial in patients with Nz‐PML, without worsening MS. The clinical course of MS may be ameliorated by PML.

The spectrum of progressive multifocal leukoencephalopathy: a practical approach

John Cunningham virus (JCV) infection of the central nervous system causes progressive multifocal leukoencephalopathy (PML) in patients with systemic immunosuppression. With the increased application of modern immunotherapy and biologics in various immune-mediated disorders, the PML risk spectrum has changed. Thus, new tools and strategies for risk assessment and stratification in drug-associated PML such as the JCV antibody indices have been introduced. Imaging studies have highlighted atypical presentations of cerebral JCV disease such as granule cell neuronopathy. Imaging markers have been developed to differentiate PML from new multiple sclerosis lesions and to facilitate the early identification of pre-clinical manifestations of PML and its immune reconstitution inflammatory syndrome. PML can be diagnosed either by brain biopsy or by clinical, radiographic and virological criteria. Experimental treatment options including immunization and modulation of interleukin-mediated immune response are emerging. PML should be considered in any patient with compromised systemic or central nervous system immune surveillance presenting with progressive neurological symptoms.