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Background and Objectives: Breast cancers (BCs) of patients with paraneoplastic neurologic syndromes and anti-Yo antibodies (Yo-PNS) overexpress human epidermal growth factor receptor 2 (HER2) and display genetic alterations and overexpression of the Yo-onconeural antigens. They are infiltrated by an unusual proportion of B cells. We investigated whether these features were also observed in patients with PNS and anti-Ri antibodies (Ri-PNS)., Methods: Using clinicopathologic data, DNA sequencing, and whole-transcriptome analysis, 28 BCs associated with Ri-PNS were characterized regarding oncological characteristics. Genetic alteration of the onconeural antigens and differential gene expression profiles were analyzed in the 12 available tumor samples and compared with those of 5 Yo-PNS tumors., Results: Ri-PNS BCs were mainly luminal B invasive carcinomas that did not overexpress HER2 and were a subtype of BCs different from the ones observed in Yo-PNS BCs. They had a low expression of wild-type TP53 and deletions of 1p chromosome. Neither overexpression nor genetic alteration of the Ri onconeural antigens was found in Ri-PNS BCs. Conversely, the nature of the antitumor immune reaction in Ri-PNS BCs was similar to the one found in Yo-PNS BCs. Ri-BCs also had a high propension for early nodal regional metastasis., Discussion: BCs associated with Ri-PNS are uncommon and the tumor subtype and their molecular and oncological characteristics are different from those of Yo-PNS and controls. Overexpression or sequence variation in the gene of the onconeural antigen is not mandatory. Conversely, Ri-PNS-associated and Yo-PNS-associated BCs display the same atypical B-cell-mediated intratumoral immune response, and tumor escape in the lymph nodes is frequent.

Objective: To investigate the differences of clinical characteristics and treatment outcomes between paraneoplastic neurologic syndrome (PNS) patients with one high-risk antibody and patients with two high-risk antibodies., Methods: We retrospectively analyzed the data of 51 PNS patients with high-risk antibody. Clinical data were extracted from the patients' electronic medical records. Clinical presentations, cerebrospinal fluid (CSF) parameters, radiological characteristics and treatment outcomes between patients with one high-risk antibody and patients with two high-risk antibodies were analyzed., Results: 41 patients with 1 high-risk antibody and 10 patients with 2 high-risk antibodies were enrolled in this study. It was found that psychobehavioral abnormality (OR = 11.327, 95% CI: 1.371 to 93.602, P = 0.024), bowel and bladder dysfunction (OR = 23.537, 95% CI: 1.753 to 316.005, P = 0.017), and total protein of CSF (OR = 61.556, 95% CI: 2.926 to 1294.974, P = 0.008) were risk factors for increased number of high-risk antibodies in PNS. After immunotherapy treatment, Expanded Disability Status Scale (EDSS) scores in PNS patients with 2 high-risk antibodies were higher than that in PNS patients with 1 high-risk antibody (4.8 ± 2.4 vs. 3.0 ± 2.4, p = 0.043). EDSS change analysis also revealed that average EDSS score decreased after treatment in PNS with 1 Ab group while increased in PNS with 2 Abs group ( p = 0.032)., Conclusions: Psychobehavioral abnormality, bowel and bladder dysfunction, and total protein of CSF were three variables associated with increased number of high-risk antibodies in PNS patients, while increased number of high-risk antibodies might indicate a poor immunotherapy response. Our findings might help to understand the association of PNS patients' clinical features and high-risk antibodies, as well as to guide clinical practice., 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 © 2025 Wang, Chen, Gao, Guo, Li, He, Jiang, Huang, Chen and Xu.)

Paraneoplastic neurological syndromes (PNS) are mostly immune-mediated, tumor-associated disorders. Earlier the 2004 PNS criteria were used which are now partially outdated due to advances in PNS research and also identification of new phenotypes and antibodies that have transformed the diagnostic approach to PNS; hence, a new criterion was proposed in 2016. They can have multifarious presentations, ranging from behavioral abnormalities to altered sensorium and coma. They can precede, be synchronous with, or follow the diagnosis of malignancy. Treatment depends on the underlying antibody and malignancy. We hereby describe an unusual presentation with dual antibody positivity in a patient who was diagnosed with lung cancer in a hospital in the same presentation., (© Journal of The Association of Physicians of India 2024.)

Background and Objectives: Paraneoplastic neurologic syndrome (PNS) diagnostic criteria were first proposed in 2004 and updated in 2021. The PNS-CARE score, derived from the updated criteria, is a composite model for assigning likelihood for patients with suspected PNS. In this study, we evaluated the utility and applicability of the 2021 PNS-CARE score and present our PNS cohort., Methods: This is a retrospective study. We identified Mayo Clinic patients suspected to have PNS (1/2005-12/2020) and collected relevant information including demographics, PNS presentation, and clinical outcomes. Inclusion criteria were the following: (1) patients with a syndrome consistent with PNS and (2) patients with sufficient information available in charts. Exclusion criteria were the following: (1) evaluation only before 2005, (2) patients not evaluated by neurology, (3) presentation after immune checkpoint inhibitors, and (4) syndromes not included in 2021 criteria. All patients were evaluated for the 2021 and 2004 PNS criteria., Results: We identified 484 patients suspected to have PNS at initial presentation, of whom 212 (44%) were considered to have PNS after completion of evaluation. Among these 212 patients, the most common autoantibodies were PCA1 (Yo)-IgG (17%), KLHL11-IgG (16%), and CRMP5-IgG (14%) and the most common phenotypes were rapidly progressive cerebellar syndrome (29%), brainstem encephalitis (14%), and limbic encephalitis (8%). The 2021 PNS criteria definite/probable categorization (PNS-CARE score ≥ 6) had a sensitivity and specificity of 93% and 100%, respectively, while the 2004 PNS criteria definite categorization had a sensitivity and specificity of 67% and 99%, respectively. We found 15 patients with a PNS-CARE score ≤5 who likely had PNS on our review. The most common presentation among these patients was KLHL11-IgG brainstem encephalitis (7/15, 47%) with likely burned-out testicular tumor., Discussion: Our study validates the PNS-CARE score. A clearer understanding of typical PNS presentation and common underlying malignancies and autoantibodies can aid in earlier and more accurate diagnosis, which is crucial for downstream clinical decisions. Some patients with an intermediate-risk phenotype do not meet probable/definite criteria despite the presence of high-risk antibodies and/or underlying malignancy.

Objective: It is unknown whether delay in diagnosis affects morbidity reportedly in paraneoplastic syndromes (PNS). We aimed to explore various aspects of PNS, including prevalence, clinical characteristics, diagnostic criteria, and treatment outcomes., Methods: We studied n-PNS diagnosis between 2016 to 2023, and included only patients with positive onconeural antibodies, who developed cancer, and exhibited a recognizable PNS phenotype., Results: We identified 12 patients with positive Abs and co-occurring cancer, most prevalent PNS antibodies included anti-GAD65, anti-Recoverin and anti-Yo. The most common phenotypes were limbic encephalitis (n=5, 42%) and encephalomyelitis (n=4,33%). Cancer preceded neurological presentation in 6 cases. Among the 6 patients who initially presented with n-PNS, median time from neurological presentation to oncologic diagnosis was 73 days, as five of them (83%) were diagnosed with cancer during oncological evaluation prompted by the PNS diagnosis or suspicion. Lymphoma was the most frequent cancer (n=3, 25%), followed by lung cancer (n=2, 17%), and ovarian cancer (n=2, 17%). Among patients who received immunotherapy as n-PNS treatment (n=9, 75%), steroids were a part of the management at 78% (n=7). Another immunotherapy used included plasmapheresis (n=5, 55%) and steroid sparing immunosuppressant (n=2, 29%). Four (33%) patients had short term therapeutic benefit with improvement or stabilization at mRS ≤ 4. Median Disability-adjusted life years (DALYs), as disease burden value, was 13 years. Death occurred in 9 of the 12 patients, with most cases deaths attributed to cancer progression. Compering to the expected median survival by type and stage of tumor, from 9 deceased patients, 56% (n=5) died younger than expected. Median survival was 410 days (range 29-2738 days), and 152 days since the appearance of n-PNS (range 8-1434 days). There were no differences in survival between patients who initially presented with n-PNS versus cancer (p=0.39)., Conclusion: In up to 8 years of follow up, there was no difference in mortality among patients who presented initially n-PNS. There was a significant decline in the quality of life, most face substantial disability and functional impairment long term., 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 © 2024 Bar Mucha, Rozenberg, Gutter Kapon, Gorenshtein, Ganelin-Cohen, Ben Hayun, Yarovinsky and Shelly.)

Background and Objectives: To define the clinical and immunologic profile of patients with paraneoplastic neurologic syndromes (PNSs) associated with Merkel cell carcinoma (MCC)., Methods: Retrospective analysis was conducted on patients with suspected MCC-related PNS assessed at the French Reference Center, and cases were identified by a systematic review of the literature (MEDLINE, Embase) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines., Results: A total of 17 patients were identified in our center and 30 in the systematic review, resulting in an overall cohort of 47 patients. The median age was 65 years (range 41-90), and 30 of 46 (65%) were men. Lambert-Eaton myasthenic syndrome (LEMS) (14/47, 29%), rapidly progressive cerebellar syndrome (11/47, 23%), and encephalomyelitis (EM) (8/47, 17%) were the most common associated clinical phenotypes. The most frequently associated neural antibodies (Abs) were voltage-gated calcium channel (VGCC)-Abs (14/45, 31%), followed by Hu-Abs (8/45, 17%) and neurofilament (NF)-Abs (8/45, 17%). Patients with NF-Abs only exhibited CNS disorders (8/8, 100%) and often had antibodies against >1 NF subunit (6/8, 75%). At onset, 26 of 43 patients (60%) had no identifiable primary skin tumor but had lymph node metastasis; these patients were more frequently men (21/26, 80%, vs 7/17, 41%; p = 0.007), had more frequently VGCC-Abs (12/26, 46%, vs 2/17, 11%, p = 0.02) predominantly among those with LEMS, and presented reduced mortality than patients with a known primary tumor (5/25, 20%, vs 8/15, 53%; p = 0.02)., Discussion: MCC-related PNSs present as a heterogeneous clinical spectrum including central and/or peripheral nervous system disorders such as LEMS, RCPS, and EM, mainly associated with VGCC-Abs, NF-Abs, and Hu-Abs. NF-Abs were only seen among patients with CNS disorders. At onset, the absence of a primary skin tumor but presence of lymph node metastasis is frequently observed, and this particular clinical presentation is linked to reduced mortality, highlighting distinctive clinical and immunologic features of MCC-related PNS.

Paraneoplastic neurologic syndromes (PNS) are a group of disorders that affect the central and the peripheral nervous system and frequently occur in patients with cancer which usually still is undiagnosed by the time the patient presents the first neurological manifestations. The discovery in the serum and cerebrospinal fluid of PNS patients of antibodies that target tumor antigens that also are normally expressed in the nervous system had a significant impact. First, the research on neuronal antibodies confirmed that most PNS are autoimmune disorders triggered by the underlying cancer supporting the use of immunotherapy to treat them; second, although the first antibodies described recognized intracellular neuronal antigens and therefore they were not pathogenic, these antibodies became robust biomarkers for the strict diagnosis of PNS; and third, the methodological approach used to characterize the first neuronal antibodies paved the way to the identification of antibodies against neuronal surface antigens that are pathogenic and responsible for some PNS and non-paraneoplastic encephalitis. Future studies should address several issues: (1) to improve the efficiency of commercial kits; (2) to provide strict criteria to select which neural antibodies should be used for the diagnosis of PNS; and (3) define in more detail the autoimmune mechanisms responsible for the brain injury in the PNS., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

The association of recognisable neurological conditions with an underlying malignancy is well described. In this review we explore the complex interplay of genetic, environmental and tumour factors which contribute to autoimmunity and paraneoplastic conditions. We review the current understanding of the pathogenesis of well recognised paraneoplastic conditions in children including Opsoclonus myoclonus ataxia syndrome, N-Methyl-D Aspartate receptor encephalitis and limbic encephalitis, and the broad approaches to treatment. Rapid advances in oncological treatment has expanded the arsenal of therapeutic modalities. We explore the broad spectrum of immune therapies in childhood cancer, and the potential neurological complications of these novel therapies, and discuss the fine balance of risk and benefit that these bring., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare with regards to this manuscript., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background and Objectives: Autoimmune encephalitis (AIE) and paraneoplastic neurologic syndromes (PNSs) encompass a heterogeneous group of antibody-associated disorders. Both the number of syndromes and commercially available antibody tests have increased considerably over the past decade. High-quality population-based data on epidemiology of these disorders and real-world performance of antibody tests are needed., Methods: In this nationwide retrospective cohort study, we identified all serum and CSF samples tested for antibodies against intracellular antigens (IAs: Hu [ANNA1], Yo [PCA1], CV2 [CRMP5], Ri [ANNA2], Ma1, Ma2 [Ta], amphiphysin, GAD65, GFAP, KLHL11, CARP VIII) or extracellular antigens (EAs: NMDAR, LGI1, Caspr2, GABA-B-R, GABA-A-R, AMPAR, DPPX, GlyR, mGluR1, VGCC, IgLON5, Tr [DNER]) between January 2016 and December 2021 in the Netherlands. Nationwide coverage was guaranteed for all antibodies except anti-GAD65 and anti-VGCC. We calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV); obtained clinical information about patients who tested positive; assigned diagnosis of AIE/PNS according to diagnostic criteria; and calculated incidence rates for IA, EA, and individual antibody-associated syndromes., Results: In the study period, 2,877 (9.5%) of 30,246 samples, belonging to 1,228 patients, tested positive. Sensitivity and specificity were high (>95%) to very high (>99%) for most tests in both serum and CSF. PPVs for several tests were moderate to poor, especially for serum testing of IA antibodies (25%-80%). Clinical data were available for 940 (76.5%) of 1,228 patients. A total of 578 AIE/PNS diagnoses were made. The incidence rate for AIE/PNS (per million person-years) increased from 4.70 (95% CI 3.72-5.85) in 2016 to 5.76 (4.69-7.00) in 2021. Overall, the incidence rate was 5.57 (5.13-6.05), 2.96 (2.64-3.31) for the EA and 2.61 (2.31-2.94) for the IA subgroup. The 4 most common AIE/PNS types were anti-NMDAR, anti-LGI1, anti-Hu, and anti-GAD65, together comprising almost two-thirds of all diagnoses (364/578, 63.0%)., Discussion: Most commercial antibody tests perform well overall, but important pitfalls remain. Although almost all tests had high specificity, PPV was only modest in the setting of these rare diseases and mass testing. We observe trends toward increasing incidence of antibody-associated AIE/PNS.

Paraneoplastic neurological syndromes (PNS) are rare autoimmune disorders triggered by the presence of a cancer. The autoimmunity is herein directed against proteins expressed both in the tumor and in the nervous system, namely the onconeural antigens, against which are directed specific autoantibodies, each of them characterizing a neurological syndrome. The mechanisms of the immune tolerance breakdown in PNS leading to the production of specific autoantibodies directed against the nervous system and leading to the immune attack begins to be explained. Each syndrome is associated with a specific histo-molecular subtype of tumor suggesting a link between the PNS genesis and oncogenesis. The expression of the onconeural antigen by these tumors is insufficient to explain the immune tolerance breakdown. In some PNS tumors, alterations of the antigen have been identified: mutations, gene copy number variation and overexpression of transcript and protein. But in others PNS, no such molecular alterations of the onconeural antigens have been demonstrated. In these cases, other mechanisms of neoantigen generation that may be involved remain to be deciphered. Cancer outcomes of PNS tumors are also characterized by the high frequency of lymph node metastasis at diagnosis. At the primary tumor site, the antitumor immune reaction seems to be particularly intense and characterized by a prominence of B-cell and Ig-secreting plasma cells that may generate the autoantibody secretion. The immune control mechanisms leading to such organization of the immune attack are not known to date. Renewed research efforts are thus needed to better understand the mechanism of immune tolerance breakdown in each PNS and determine potential targets to meet the therapeutic challenges posed by these rare disorders., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Introduction: On the palliative care ward, we treated a man with a small cell lung cancer who was suffering from vertigo for six years, however the vertigo got stronger the last six months with pronounced coordination disorders. After several examinations, the cause was a paraneoplastic neurologic syndrome (PNS) with Hu-antibodies. PNS are various neurological malfunctions, which occur mostly in certain patterns. The pathogenesis is immune-mediated through a tumor. This is the reason why the treatment of the PNS is within the treatment of the tumor., Competing Interests: Die Autorin und der Autor haben keine Interessenkonflikte im Zusammenhang mit diesem Artikel deklariert., (© 2024 Aerzteverlag medinfo AG.)

Paraneoplastic neurological syndromes occur due to immune-mediated neuronal dysfunction secondary to systemic malignancy, and symptoms can usually be seen before malignancy. There are many subtypes that depend on the antibodies present or the proteins they target. Accurate epidemiological data are lacking as it is difficult to diagnose. We would like to present a case of anti-Yo antibody-associated encephalitis due to breast cancer in a 47-year-old male patient. When we searched the literature, we did not find a case of anti-Yo-associated autoimmune encephalitis due to breast adenocarcinoma in a male patient. For this reason, we find it worth presenting our case., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Ataxia with anti-regulator of G-protein signaling 8 autoantibodies (RGS8-Abs) is an autoimmune disease recently described in four patients. The present study aimed to identify other patients with RGS8-Abs, describe their clinical features, including the link between RGS8-related autoimmune cerebellar ataxia (ACA) and cancer. Patients with RGS8-Abs were identified retrospectively in the biological collections of the French Reference Center for Paraneoplastic Neurological Syndrome and the University of California San Francisco Center for Encephalitis and Meningitis. Clinical data were collected, and cerebrospinal fluid, serum, and tumor pathological samples were retrieved to characterize the autoantibodies and the associated malignancies. Only three patients with RGS8-Abs were identified. All of them presented with a pure cerebellar ataxia of mild to severe course, unresponsive to current immunotherapy regimens for ACA. Two patients presented with a Hodgkin lymphoma of the rare specific subtype called nodular lymphocyte-predominant Hodgkin lymphoma, with very mild extension. Autoantibodies detected in all patients enriched the same epitope on the RGS8 protein, which is an intracellular protein physiologically expressed in Purkinje cells but also ectopically expressed specifically in lymphoma cells of patients with RGS8-related ACA. The present results and those of the four cases previously described suggest that RGS8-Abs define a new paraneoplastic neurological syndrome of extreme rarity found mostly in middle-aged males that associates pure cerebellar ataxia and a particular lymphoma specifically expressing the RGS8 antigen. As in other paraneoplastic ACA with intracellular antigen, the disease course is severe, and patients tend to exhibit a poor response to immune therapy., (© 2024. The Author(s).)

Introduction: Anti-neuronal antibodies target antigens produced by tumour cells and cells of nervous system. These antibodies are formed as a result of autoimmune response elicited by the underlying malignancy, when proteins restricted to immune privileged neurons are presented by the tumour. Previous studies have shown presence of anti-neuronal antibodies in systemic lupus erythematosus and neuropsychiatric lupus (NPSLE) but information on individual antibodies and their pathogenic role is lacking., Aims/objective: To assess the frequency of anti-neuronal antibodies in our neuropsychiatric lupus cohort and to assess any significant association with specific neurological syndrome and to see if the antibodies were more likely to occur in active rather than inactive neuropsychiatric lupus., Methodology: This cross-sectional study was conducted in our center from 2019 to 2022. Neuropsychiatric manifestations were defined according to 1999 American College of Rheumatology (ACR) nomenclature and case definitions for neuropsychiatric lupus. Samples were taken from active or inactive NPSLE patients with their informed consent. Testing was done on an anti-neuronal antigen panel which consisted of [Amphiphysin, CV2, GAD 65, PNMA2 (Ma-2/Ta), Ri, Yo, Hu, recoverin, SOX1, titin, Zic, Tr)] by semi-quantitative Line immune assay. Association between the categorical variables and antibody positivity group was established using chi-square/Fisher's exact test as appropriate., Results: 65 patients were recruited, of which 23 (35%) patients had active NPSLE at the time of sample collection. Anti-neuronal antibodies were positive in 13/65 (20%) patients with anti-Gad 65 antibodies having the highest frequency (6.2%) followed by anti CV 2 (3.1%), anti Sox1 (3.1%), anti Amphiphysin (3.1%) anti recoverin (1.5%), anti Yo (1.5%) and anti Zic (1.5%). The panel of anti-neuronal antibodies did not show any specific association with NPSLE features.However, an interesting finding was that, patients with active disease had higher odds of having anti-neuronal antibodies with an OR = 10 (95% CI:2.38 -42) ( p < 0.001) than inactive disease., Conclusion: Anti-neuronal antibodies were more likely to be positive in active neuropsychiatric lupus patients, and these antibodies which are commonly used to diagnose paraneoplastic syndromes may have a potential role in the diagnosis of NPSLE., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives: To investigate the association between human leukocyte antigen (HLA) and paraneoplastic neurological syndromes (PNS) with Hu antibodies, and potential specificities according to clinical presentation and cancer status., Methods: HLA genotypes at four-digit resolution were imputed from available genome-wide association data. Allele carrier frequencies were compared between patients (whole cohort, n = 100, and according to clinical presentation and cancer status) and matched healthy controls (n = 508) using logistic regression controlled by the three main principal components., Results: The clinical presentation of 100 anti-Hu patients involved the central nervous system (28, 28%), the peripheral nervous system (36, 36%) or both combined (36, 36%). Cancer diagnosis was certain in 75 (75%). HLA association analyses revealed that anti-Hu PNS patients were more frequently carriers of DQA1*05:01 (39% vs. 19%, OR = 2.8 [1.74-4.49]), DQB1*02:01 (39% vs. 18%, OR = 2.88 [1.79-4.64]) and DRB1*03:01 (41% vs. 19%, OR = 2.92 [1.80-4.73]) than healthy controls. Remarkably, such DR3 ~ DQ2 association was absent in patients with pure central involvement, but more specific to those manifesting with peripheral involvement: DQA1*05:01 (OR = 3.12 [1.48-6.60]), DQB1*02:01 (OR = 3.35 [1.57-7.15]) and DRB1*03:01 (OR = 3.62 [1.64-7.97]); being even stronger in cases with sensory neuropathy, DQA1*05:01 (OR = 4.41 [1.89-10.33]), DQB1*02:01 (OR = 4.85 [2.04-11.53]) and DRB1*03:01 (OR = 5.79 [2.28-14.74]). Similarly, DR3 ~ DQ2 association was only observed in patients with cancer., Discussion: Patients with anti-Hu PNS show different HLA profiles according to clinical presentation and, probably, cancer status, suggesting pathophysiological differences., (© 2024. The Author(s).)

Objective: This article reviews the clinical presentations, neural antibody associations, and oncologic accompaniments of paraneoplastic neurologic syndromes and neurologic autoimmunity in the context of immune checkpoint inhibitor (ICI) cancer immunotherapy., Latest Developments: Neural antibody discovery has improved the diagnosis of paraneoplastic neurologic syndromes. Neural antibodies also delineate the underlying disease pathophysiology and thus inform outcomes and treatments. Neural antibodies specific for extracellular proteins have pathogenic potential, whereas antibodies specific for intracellular targets are biomarkers of a cytotoxic T-cell immune response. A recent update in paraneoplastic neurologic syndrome criteria suggests high- and intermediate-risk phenotypes as well as neural antibodies to improve diagnostic accuracy in patients with paraneoplastic neurologic syndromes; a score was created based on this categorization. The introduction of ICI cancer immunotherapy has led to an increase in cancer-related neurologic autoimmunity with distinct clinical phenotypes., Essential Points: Paraneoplastic neurologic syndromes reflect an ongoing immunologic response to cancer mediated by effector T cells or antibodies. Paraneoplastic neurologic syndromes can present with manifestations at any level of the neuraxis, and neural antibodies aid diagnosis, focus cancer screening, and inform prognosis and therapy. In patients with high clinical suspicion of a paraneoplastic neurologic syndrome, cancer screening and treatment should be undertaken, regardless of the presence of a neural antibody. ICI therapy has led to immune-mediated neurologic complications. Recognition and treatment lead to improved outcomes., (Copyright © 2024 American Academy of Neurology.)

Gastrointestinal pseudo-obstruction (GIPO) is a phenotype of the paraneoplastic neurological syndrome (PNS). We herein report a case of small-cell lung carcinoma (SCLC) with GIPO elicited by an immune checkpoint inhibitor (ICI). A 75-year-old man with SCLC developed intractable intestinal obstruction after receiving one course of anticancer drugs (durvalumab, etoposide, and carboplatin). The serum anti-Hu antibody (Hu-Ab) was positive, and the patient was diagnosed with GIPO. Corticosteroid treatment did not improve the GIPO, and the patient died. There are few reports of GIPO after ICI treatment in patients with lung cancer, so a further investigation will be required to elucidate the mechanism by which ICIs elicit PNS. Checking for neuronal antibodies may help identify patients with SCLC who are at risk of developing PNS due to ICI treatment.

Objectives: To report an autoimmune paraneoplastic encephalitis characterized by immunoglobulin G (IgG) antibody targeting synaptic protein calmodulin kinase-like vesicle-associated (CAMKV)., Methods: Serum and cerebrospinal fluid (CSF) samples harboring unclassified antibodies on murine brain-based indirect immunofluorescence assay (IFA) were screened by human protein microarray. In 5 patients with identical cerebral IFA staining, CAMKV was identified as top-ranking candidate antigen. Western blots, confocal microscopy, immune-absorption, and mass spectrometry were performed to substantiate CAMKV specificity. Recombinant CAMKV-specific assays (cell-based [fixed and live] and Western blot) provided additional confirmation., Results: Of 5 CAMKV-IgG positive patients, 3 were women (median symptom-onset age was 59 years; range, 53-74). Encephalitis-onset was subacute (4) or acute (1) and manifested with: altered mental status (all), seizures (4), hyperkinetic movements (4), psychiatric features (3), memory loss (2), and insomnia (2). Paraclinical testing revealed CSF lymphocytic pleocytosis (all 4 tested), electrographic seizures (3 of 4 tested), and striking MRI abnormalities in all (mesial temporal lobe T2 hyperintensities [all patients], caudate head T2 hyperintensities [3], and cortical diffusion weighted hyperintensities [2]). None had post-gadolinium enhancement. Cancers were uterine adenocarcinoma (3 patients: poorly differentiated or neuroendocrine-differentiated in 2, both demonstrated CAMKV immunoreactivity), bladder urothelial carcinoma (1), and non-Hodgkin lymphoma (1). Two patients developed encephalitis following immune checkpoint inhibitor cancer therapy (atezolizumab [1], pembrolizumab [1]). All treated patients (4) demonstrated an initial response to immunotherapy (corticosteroids [4], IVIG [2]), though 3 died from cancer., Interpretation: CAMKV-IgG is a biomarker of immunotherapy-responsive paraneoplastic encephalitis with temporal and extratemporal features and uterine cancer as a prominent oncologic association. ANN NEUROL 2024;96:21-33., (© 2024 American Neurological Association.)

Background: Brachial amyotrophic diplegia (BAD) is typically linked to a neurodegenerative etiology such as amyotrophic lateral sclerosis (ALS). Clinical and serological characterizations of paraneoplastic neurologic syndromes resembling BAD are limited., Methods: A retrospective chart review of patients with BAD-like presentations was conducted. Clinical/paraclinical features of paraneoplastic BAD and neurodegenerative BAD cases were compared., Results: Between 2017 and 2023, 13 cases of BAD were identified, of these 10 were neurodegenerative BAD (ALS variant), and 3 cases associated with paraneoplastic autoimmunity. An additional paraneoplastic BAD case diagnosed in 2005 was included. LUZP4-IgG was detected in all four paraneoplastic cases, with coexisting KLHL11-IgG in three cases and ANNA1 (anti-Hu)-IgG in one case. Out of the four paraneoplastic cases, two patients had seminoma, while the remaining two had limited cancer investigation. Three patients exhibited bi-brachial weakness as the initial symptom before the onset of brainstem symptoms or seizures. Compared to BAD patients with a neurodegenerative etiology, a higher proportion of paraneoplastic cases had ataxia (75% vs 0%, p = 0.011). Other clinical features only detected in the paraneoplastic BAD group were vertigo (n = 2), hearing loss (n = 2) and ophthalmoplegia (n = 2). Electrodiagnostic studies in these patients revealed cervical myotome involvement, supportive of motor neuronopathy. All paraneoplastic cases but none of the neurodegenerative BAD cases exhibited inflammatory cerebrospinal fluid (CSF) findings (lymphocytic pleocytosis and/or supernumerary oligoclonal bands; p = 0.067). Despite the administration of immunotherapy and/or cancer treatment, none of the paraneoplastic patients reported clinical improvement., Discussion: BAD or bi-brachial neurogenic weakness is a rare phenotypic presentation associated with paraneoplastic autoimmunity. Co-existing features of brainstem dysfunction or cerebellar ataxia should prompt further paraneoplastic evaluation. Common serological and cancer associations among these cases include LUZP4-IgG and KLHL11-IgG, along with testicular germ cell tumors, respectively., (© 2024. Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose of Review: The increasing recognition and diagnosis of autoimmune encephalitis (AE) and paraneoplastic neurological syndromes (PNS) is partly due to neural autoantibody testing and discovery. The past two decades witnessed an exponential growth in the number of identified neural antibodies. This review aims to summarize recent rare antibody discoveries in the context of central nervous system (CNS) autoimmunity and evaluate the ongoing debate about their utility., Recent Findings: In the last 5 years alone 15 novel neural autoantibody specificities were identified. These include rare neural antibody biomarkers of autoimmune encephalitis, cerebellar ataxia or other movement disorders, including multifocal presentations., Summary: Although the clinical applications of these rare antibody discoveries may be limited by the low number of positive cases, they still provide important diagnostic, prognostic, and therapeutic insights., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background and Purpose: Paraneoplastic neurological autoimmunity is well described with small-cell lung cancer, but information is limited for other neuroendocrine neoplasms (NENs)., Methods: Adult patients with histopathologically confirmed non-pulmonary NENs, neurological autoimmunity within 5 years of NEN diagnosis, and neural antibody testing performed at the Mayo Clinic Neuroimmunology Laboratory (January 2008 to March 2023) were retrospectively identified. Control sera were available from patients with NENs without neurological autoimmunity (116)., Results: Thirty-four patients were identified (median age 68 years, range 31-87). The most common primary tumor sites were pancreas (nine), skin (Merkel cell, eight), small bowel/duodenum (seven), and unknown (seven). Five patients received immune checkpoint inhibitor (ICI) therapy before symptom onset; symptoms preceded cancer diagnosis in 62.1% of non-ICI-treated patients. The most frequent neurological phenotypes (non-ICI-treated) were movement disorders (12; cerebellar ataxia in 10), dysautonomia (six), peripheral neuropathy (eight), encephalitis (four), and neuromuscular junction disorders (four). Neural antibodies were detected in 55.9% of patients studied (most common specificities: P/Q-type voltage-gated calcium channel [seven], muscle-type acetylcholine receptor [three], anti-neuronal nuclear antibody type 1 [three], and neuronal intermediate filaments [two]), but in only 6.9% of controls. Amongst patients receiving cancer or immunosuppressive therapy, 51.6% had partial or complete recovery. Outcomes were unfavorable in 48.3% (non-ICI-treated) and neural autoantibody positivity was associated with poor neurological outcome., Discussion: Neurological autoimmunity associated with non-pulmonary NENs is often multifocal and can be treatment responsive, underscoring the importance of rapid recognition and early treatment., (© 2024 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Purpose of Review: We summarize the recent discoveries on genetic predisposition to autoimmune encephalitis and paraneoplastic neurological syndromes (PNS), emphasizing clinical and pathophysiological implications., Recent Findings: The human leukocyte antigen (HLA) is the most studied genetic factor in autoimmune encephalitis and PNS. The HLA haplotype 8.1, which is widely known to be related to systemic autoimmunity, has been only weakly associated with a few types of autoimmune encephalitis and PNS. However, the strongest and most specific associations have been reported in a subgroup of autoimmune encephalitis that comprises antileucine-rich glioma-inactivated 1 (LGI1) limbic encephalitis, associated with DRB1∗07 : 01 , anticontactin-associated protein-like 2 (CASPR2) limbic encephalitis, associated with DRB1∗11 : 01 , and anti-IgLON5 disease, associated with DRB1∗10 : 01∼DQA1∗01∼DQB1∗05 . Non-HLA genes have been poorly investigated so far in autoimmune encephalitis, mainly in those lacking HLA associations such as anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, with only a few genome-wide association studies (GWAS) reporting equivocal results principally limited by small sample size., Summary: Genetic predisposition seems to be driven mostly by HLA in a group of autoimmune encephalitis characterized by being nonparaneoplastic and having predominantly IgG4 autoantibodies. The contribution of non-HLA genes, especially in those diseases lacking known or strong HLA associations, will require large cohorts enabling GWAS to be powerful enough to render meaningful results., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background and Objectives: Dysautonomia has been associated with paraneoplastic neurological syndrome (PNS)-related mortality in anti-Hu PNS, but its frequency and spectrum remain ill-defined. We describe anti-Hu patients with dysautonomia, estimate its frequency, and compare them to patients without dysautonomia., Methods: Patients with anti-Hu antibodies diagnosed in the study centre (1990-2022) were retrospectively reviewed; those with autonomic signs and symptoms were identified., Results: Among 477 anti-Hu patients, 126 (26%) had dysautonomia (the only PNS manifestation in 7/126, 6%); gastrointestinal (82/126, 65%), cardiovascular (64/126, 51%), urogenital (24/126, 19%), pupillomotor/secretomotor (each, 11/126, 9%), and central hypoventilation (10/126, 8%). Patients with isolated CNS involvement less frequently had gastrointestinal dysautonomia than those with peripheral (alone or combined with CNS) involvement (7/23, 30% vs. 31/44, 70% vs. 37/52, 71%; P = 0.002); while more frequently central hypoventilation (7/23, 30% vs. 1/44, 2.3% vs. 2/52, 4%; P < 0.001) and/or cardiovascular alterations (18/23, 78% vs. 20/44, 45% vs. 26/52, 50%; P = 0.055). Median [95% CI] overall survival was not significantly different between patients with (37 [17; 91] months) or without dysautonomia (28 [22; 39] months; P = 0.78). Cardiovascular dysautonomia (HR: 1.57, 95% CI [1.05; 2.36]; P = 0.030) and central hypoventilation (HR: 3.51, 95% CI [1.54; 8.01]; P = 0.003) were associated with a higher risk of death, and secretomotor dysautonomia a lower risk (HR: 0.28, 95% CI [0.09; 0.89]; P = 0.032). Patients with cardiovascular dysautonomia dying ≤ 1 year from clinical onset had severe CNS (21/27, 78%), frequently brainstem (13/27, 48%), involvement., Discussion: Anti-Hu PNS dysautonomia is rarely isolated, frequently gastrointestinal, cardiovascular and urogenital. CNS dysfunction, particularly brainstem, associates with lethal cardiovascular alterations and central hypoventilation, while peripheral involvement preferentially associates with gastrointestinal or secretomotor dysautonomia, being the latest more indolent., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Background: The clinical spectrum of melanoma-associated neurological autoimmunity, whether melanoma-associated paraneoplastic neurological syndromes (PNS) or induced by immune checkpoint inhibitors (ICI), is not well characterized. We aim to describe the clinical spectrum of melanoma-associated neurological autoimmunity., Methods: A systematic review of the literature combined with patients from French databases of paraneoplastic neurological syndromes was conducted. All melanoma patients with a possible immune-mediated neurologic syndrome were included and classified according to whether they had previously been exposed to ICI (ICI-neurotoxicity) or not (ICI-naïve) at first neurological symptoms., Results: Seventy ICI-naïve (literature: n = 61) and 241 ICI-neurotoxicity patients (literature: n = 180) were identified. Neuromuscular manifestations predominated in both groups, but peripheral neuropathies were more frequent in ICI-neurotoxicity patients (39.4% vs 21.4%, p = 0.005) whereas myositis was more frequent in ICI-naïve patients (42.9% vs 18.7%, p < 0.001). ICI-naïve patients had also more frequent central nervous system (CNS) involvement (35.7% vs 23.7%, p = 0.045), classical paraneoplastic syndrome (25.7% vs 5.8%, p < 0.001), and more frequently positive for anti-neuron antibodies (24/32, 75.0% vs 38/90, 42.2%, p = 0.001). Although more ICI-neurotoxicity patients died during the acute phase (22/202, 10.9% vs 1/51, 2.0%, p = 0.047), mostly myositis patients (14/22, 63.6%), mortality during follow-up was higher in ICI-naïve patients (58.5% vs 29.8%, p < 0.001). There was no significant difference in the frequency of life independence (mRS ≤ 2) in the surviving patients in both groups (95.5% vs 91.0%, p = 0.437)., Conclusions: Melanoma-associated PNS appear remarkably rare. The clinical similarities observed in neurological autoimmunity between ICI-treated and ICI-naïve patients, characterized predominantly by demyelinating polyradiculoneuropathy and myositis, suggest a potential prior immunization against melanoma antigens contributing to ICI-related neurotoxicity., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Rationale: Paraneoplastic neurological syndrome with anti-Hu antibody (Hu-PNS) is a neurological disorder that occur in patients with malignancy. The syndrome has a wide range of presentations and can present before diagnosis of primary malignancy. Familiarity with these paraneoplastic neurological syndromes can help early recognition and take appropriate regimens., Patients Concerns: Diagnosis and treatment of Hu-PNS., Diagnoses: This is retrospective study that analyzed the clinical data of this case. Through retrospective analysis and targeted antibody screening, serum anti-Hu antibody was detected. Subsequent spinal imaging revealed a mass in the paraspinal region, which was confirmed as ganglioneuroblastoma by pathologic examination., Interventions: The child was treated with a course of intravenous immunoglobulin and radical surgical operation without chemotherapy., Outcomes: The neurological symptoms were gradually improved and no signs indicate disease progression or tumor recurrence., Lessons: Hu-PNS has rarely been reported in children with ganglioneuroblastomas. They can mimic non-neoplastic processes, making detection and diagnosis difficult. Serum and/or cerebrospinal fluid onconeural antibody can strongly indicate occult cancers. Early detection of paraneoplastic neurological syndromes can help take appropriate regimens and improve prognosis., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background and Objectives: While patients with paraneoplastic autoimmune encephalitis (AE) with gamma-aminobutyric-acid B receptor antibodies (GABA B R-AE) have poor functional outcomes and high mortality, the prognosis of nonparaneoplastic cases has not been well studied., Methods: Patients with GABA B R-AE from the French and the Dutch Paraneoplastic Neurologic Syndromes Reference Centers databases were retrospectively included and their data collected; the neurologic outcomes of paraneoplastic and nonparaneoplastic cases were compared. Immunoglobulin G (IgG) isotyping and human leukocyte antigen (HLA) genotyping were performed in patients with available samples., Results: A total of 111 patients (44/111 [40%] women) were enrolled, including 84 of 111 (76%) paraneoplastic and 18 of 111 (16%) nonparaneoplastic cases (cancer status was undetermined for 9 patients). Patients presented with seizures (88/111 [79%]), cognitive impairment (54/111 [49%]), and/or behavioral disorders (34/111 [31%]), and 54 of 111 (50%) were admitted in intensive care unit (ICU). Nonparaneoplastic patients were significantly younger (median age 54 years [range 19-88] vs 67 years [range 50-85] for paraneoplastic cases, p < 0.001) and showed a different demographic distribution. Nonparaneoplastic patients more often had CSF pleocytosis (17/17 [100%] vs 58/78 [74%], p = 0.02), were almost never associated with KTCD16-abs (1/16 [6%] vs 61/70 [87%], p < 0.001), and were more frequently treated with second-line immunotherapy (11/18 [61%] vs 18/82 [22%], p = 0.003). However, no difference of IgG subclass or HLA association was observed, although sample size was small (10 and 26 patients, respectively). After treatment, neurologic outcome was favorable (mRS ≤2) for 13 of 16 (81%) nonparaneoplastic and 37 of 84 (48%) paraneoplastic cases ( p = 0.03), while 3 of 18 (17%) and 42 of 83 (51%) patients had died at last follow-up ( p = 0.008), respectively. Neurologic outcome no longer differed after adjustment for confounding factors but seemed to be negatively associated with increased age and ICU admission. A better survival was associated with nonparaneoplastic cases, a younger age, and the use of immunosuppressive drugs., Discussion: Nonparaneoplastic GABA B R-AE involved younger patients without associated KCTD16-abs and carried better neurologic and vital prognoses than paraneoplastic GABA B R-AE, which might be due to a more intensive treatment strategy. A better understanding of immunologic mechanisms underlying both forms is needed.

Objective: This study aimed to explore the clinical characteristics and temporal disease course of patients with autoimmune encephalitis (AE) and paraneoplastic neurological syndrome (PNS) in Sweden., Methods: Thirty-seven antibody-positive AE and PNS cases were identified in the Healthcare region Mid Sweden between 2015 and 2019. Clinical data were collected through a retrospective review of electronic health records. Patients were divided into three subgroups based on antibody type: neuronal surface antibodies (NSAbs), onconeural antibodies, and anti-GAD65 antibodies., Results: Nineteen patients had NSAbs, 11 onconeural antibodies, and seven anti-GAD65 antibodies. Anti-LGI1 and anti-NMDAR were the most frequently detected NSAbs, with anti-NMDAR cases having an older-than-expected age distribution (median age 40, range 17-72). Only 11 of 32 (30%) of patients had findings suggesting encephalitis on initial MRI, but 28 of 31 (90%) had pathological findings on initial cerebrospinal fluid analysis. All patients but one had abnormal EEG findings. Median time to immunotherapy was comparable among the three subgroups, whereas patients with anti-LGI1, anti-CASPR2, and anti-IgLON5 had an eightfold longer time to immunotherapy than anti-NMDAR and anti-GABA-B (p = .0016). There was a seasonal variation in onset for patients with non-tumor-related NSAbs and anti-GAD65 antibodies, with most patients (72%) falling ill in spring or summer., Conclusion: Swedish patients with AE and PNS had similar clinical characteristics as previously described cohorts from other geographical regions except for anti-NMDAR encephalitis, with older onset than expected. The onset of non-tumor-related AE occurred predominantly in the warm seasons, and AE with a more insidious onset was associated with delayed treatment initiation., (© 2024 The Authors. Brain and Behavior published by Wiley Periodicals LLC.)

Paraneoplastic disorders of the peripheral nervous system are immune-mediated neurological syndromes associated with tumors. Several clinical phenotypes have been associated with these disorders. Sensory neuronopathy is the most well-known clinical phenotype, and is caused by neuronal cell injury to the dorsal root ganglia. Symptoms of the peripheral nervous system usually lead to the discovery of tumors. Antineuronal antibodies are occasionally identified in the serum and/or cerebrospinal fluid of these patients. The prevalence of small-cell lung cancer is notable in these patients. Early tumor resection, coupled with the initiation of immunotherapy, may prove effective in improving and stabilizing clinical symptoms.

Background and Objectives: Paraneoplastic neurologic syndromes (PNSs) are remote neurologic immune-related effects of tumors. The clinical characteristics of pediatric PNSs remain unclear. We retrospectively examined the clinical characteristics of cases of pediatric PNSs and assessed the performance of the 2021 diagnostic criteria in children., Methods: Patients hospitalized in the Beijing Children's Hospital between June 2015 and June 2023 and fulfilling the description of definite by 2004 diagnostic criteria of PNSs were included. A retrospective analysis of clinical characteristics was conducted, and the 2021 diagnostic criteria were applied to rediagnostic stratification., Results: Among the 42 patients included, the most common neurologic syndrome was opsoclonus-myoclonus syndrome (OMS) (62%), followed by rapidly progressive cerebellar syndrome (26%). Most tumors were neuroblastomas (88%), with few being ovarian teratomas (10%). Approximately 71% (30/42) of patients were classified as definite and 24% (10/42) as probable according to the 2021 criteria. All cases judged as probable exhibited rapidly progressive cerebellar ataxia with neuroblastoma. For OMS, chemotherapy was administered based on the tumor's risk stage, accompanied by regular infusion of IV gamma globulin and oral steroids following tumor diagnosis. Twenty-one patients underwent regular follow-ups over 4.92 (0.58-7.58) years. The initial hospitalization recorded a median score of 12 (7-14) on the Mitchell and Pike OMS rating scale, decreasing to 0 (0-5) at the final follow-up. In cases of rapidly progressive cerebellar syndrome, a similar therapeutic regimen was used. Nine patients underwent regular follow-ups over 4.42 (1.17-7.50) years. The mean modified Rankin scale score at first hospitalization was 4 (3-4), reducing to 1 (0-4) at the final follow-up. Only 17% (5/30) of patients across both groups exhibited poor response to this regimen. Among these 5 patients, 4 belonged to the low-risk group (without chemotherapy)., Discussion: OMS followed by rapidly progressive cerebellar ataxia are the most common forms of PNSs in children and are associated with neuroblastoma. An aggressive approach with multiple immunotherapies may improve the prognosis of neuroblastoma-associated PNSs. The 2021 criteria perform well in pediatric PNSs. However, we propose upgrading the classification of antibody-negative rapidly progressive cerebellar ataxia with neuroblastoma to definite diagnosis. This adjustment aims to further improve the diagnostic efficacy of this diagnostic criterion in childhood.

Background: Recently, the paraneoplastic neurologic syndrome (PNS) diagnostic criteria have received a major update with a new score system over the past 16 years. We aimed to evaluate the diagnostic performance and clinical utility in China., Methods: An eligible cohort of 113 Chinese patients diagnosed with PNSs from the Second Affiliated Hospital School of Medicine Zhejiang University and published data were enrolled retrospectively. Data including clinical phenotype, antibody type, the presence of cancer, and duration of follow-up were reviewed and re-evaluated to classify the diagnostic levels for the 2004 and 2021 PNS criteria. The performances of these 2 criteria were compared. The critical parameters of antibody and cancer for the updated criteria were further explored., Results: The cohort consisted of 69 males and 44 females with a median age of 60 years. Limbic encephalitis (23, 20.4%), anti-Hu antibody (32, 28.3%), and small-cell lung cancer (32, 28.3%) were the most common clinical phenotype, detected antibody, and concomitant cancer, respectively. A total of 97 (85.8%) patients were diagnosed with definite PNS according to the 2004 criteria: only 42.3% (41/97) fulfilled the 2021 criteria, while the remaining 40, 14, and 2 re-diagnosed with probable PNS, possible PNS, and non-PNS. The requirement of cancers consistent with antibody and phenotype increased the specificity and thus greatly enhanced the accuracy of the 2021 criteria., Conclusion: The updated criteria for PNS emphasized the consistency between cancer phenotype and antibody and showed a better diagnostic value. A better diagnostic yield could benefit disease management., 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 © 2022 Cai, Qiao, Lai, Zheng, Yang, Fang, Shen, Zhang and Ding.)

Autoimmune encephalitis with antibodies against the gamma-aminobutyric acid-B receptor is a relatively rare disease. We report a case with characteristic symptoms of limbic encephalitis associated with combined small cell lung carcinoma. The brain magnetic resonance imaging showed bilateral temporal lesions and the photoemission tomography revealed regional heterogenous metabolism across the brain. The double labeling of anti-gamma-aminobutyric acid-B receptor autoantibodies both in the tissues of neuroendocrine and small cell neoplasia was a unique feature of this patient., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Paraneoplastic neurological syndromes (PNS) are rare immune-mediated disorders, and the detection of onconeural antibodies is helpful for PNS diagnosis. The aim of this study was to investigate the clinical characteristics of patients with PNS with positive onconeural antibodies in a single center in Hubei, China. We retrospectively analyzed the clinical characteristics of 54 patients with positive onconeural antibodies from January 2016 to September 2020. Among 780 patients with suspected PNS, 54 (6.9%) had positive onconeural antibodies. Of those 54 patients, 28 (51.8%) were diagnosed with definite PNS and 13 (24.1%) with possible PNS. Eighteen (33.3%) patients were confirmed with cancer. Ten PNS syndromes were detected among the 28 patients with definite PNS, and they had either classical (12/28, 42.8%) or non-classical syndromes (17/28, 60.7%). Peripheral neuropathy (9/28, 32.1%), subacute cerebellar degeneration (4/28, 14.3%), and limbic encephalitis (4/28, 14.3%) were the most common PNS syndromes. The anti-CV2/CRMP5-antibody was observed most frequently. Lung cancer was the most common tumor type. For patients with possible PNS, peripheral neuropathy was the most common PNS syndrome, and the anti-Tr-antibody was the most frequent onconeural antibody. Immunotherapy was effective in treating PNS. The anti-CV2/CRMP5-antibody was the most subsequently observed antibody. The manifestations of PNS are diverse and include peripheral neuropathy, subacute cerebellar degeneration, and limbic encephalitis. In patients with PNS, lung cancer was the most common tumor., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objective: This study was undertaken to describe a novel biomarker of germ cell tumor and associated paraneoplastic neurological syndrome (PNS)., Methods: Archival sera from patients with germ cell tumor-associated PNS were evaluated. We identified a common autoantigen in a human testicular cancer cell line (TCam-2) by Western blot and mass spectrometry. Its identity was confirmed by recombinant-protein Western blot, enzyme-linked immunosorbent assay (ELISA), and cell-based assay. Autoantibody specificity was confirmed by analyzing assorted control sera/cerebrospinal fluid., Results: Leucine zipper 4 (LUZP4)-immunoglobulin G (IgG) was detected in 28 patients' sera, 26 of whom (93%) were men. The median age at neurological symptom onset was 45 years (range = 28-84). Median titer (ELISA) was 1:300 (1:50 to >1:6,400, normal value < 1:50). Coexistent kelchlike protein 11-IgG was identified in 18 cases (64%). The most common presenting phenotype was rhombencephalitis (17/28, 61%). Other presentations included limbic encephalitis (n = 5, 18%), seizures and/or encephalitis (n = 2, 7%), and motor neuronopathy/polyradiculopathy (n = 4, 14%). The most common malignancy among cancer-evaluated PNS patients was seminoma (21/27, 78%). Nine of the 21 seminomas detected by whole-body fluorodeoxyglucose positron emission tomography scan (43%) were extratesticular. Both female patients had ovarian teratoma. Regressed testicular germ cell tumors were found in 4 patients. Exposure of T-cell-dendritic-cell cocultures from chronic immunosuppression-naïve LUZP4-IgG-seropositive patients to recombinant LUZP4 protein evoked a marked increase in CD69 expression on both CD4+ and CD8+ T cells when compared to vehicle-exposed and healthy control cultures., Interpretation: LUZP4-IgG represents a novel serological biomarker of PNS and has high predictive value for germ cell tumors. The demonstrated antigen-specific T-cell responses support a CD8+ T-cell-mediated cytotoxic paraneoplastic and antitumor potential. ANN NEUROL 2021;89:1001-1010., (© 2021 American Neurological Association.)

Paraneoplastic neurological syndromes (PNS) are a group of rare and severe immune-mediated disorders that affect the nervous system in patients with cancer. The best way to diagnose a paraneoplastic neurological disorder is to identify anti-onconeural protein antibodies that are specifically associated with various cancers. The aim of this multicentric study was to clinically and immunologically characterize patients with PNS and study their association with cancer. Patients suspected to have PNS were enrolled from various clinical centres and were characterized immunologically. This study population consisted of 112 patients. Onset of PNS was mainly subacute (76 %). PNS patients had various neurological disorders and symptoms. PNS developed before the diagnosis of cancer in 28 definite PNS patients and in six suspected PNS patients. The most frequent autoantibodies detected in PNS patients were anti-Hu and anti-Yo. One definite PNS patient with cerebellar syndrome had anti-Tr antibody and seven patients had atypical antibodies. The literature associates these antibodies with various neurological disorders and cancers. Our observations confirm the important role of autoantibodies in PNS and their importance for the early diagnosis of cancer in PNS patients.

Importance: Recognizing the presenting and immunopathological features of Kelch-like protein-11 immunoglobulin G seropositive (KLHL11 IgG+) patients may aid in early diagnosis and management., Objective: To describe expanding neurologic phenotype, cancer associations, outcomes, and immunopathologic features of KLHL11 encephalitis., Design, Setting, and Participants: This retrospective tertiary care center study, conducted from October 15, 1998, to November 1, 2019, prospectively identified 31 KLHL11 IgG+ cases in the neuroimmunology laboratory. Eight were identified by retrospective testing of patients with rhomboencephalitis (confirmed by tissue-based-immunofluorescence and transfected-cell-based assays)., Main Outcomes and Measures: Outcome variables included modified Rankin score and gait aid use., Results: All 39 KLHL11 IgG+ patients were men (median age, 46 years; range, 28-73 years). Initial clinical presentations were ataxia (n = 32; 82%), diplopia (n = 22; 56%), vertigo (n = 21; 54%), hearing loss (n = 15; 39%), tinnitus (n = 14; 36%), dysarthria (n = 11; 28%), and seizures (n = 9; 23%). Atypical neurologic presentations included neuropsychiatric dysfunction, myeloneuropathy, and cervical amyotrophy. Hearing loss or tinnitus preceded other neurologic deficits by 1 to 8 months in 10 patients (26%). Among patients screened for malignancy (n = 36), testicular germ-cell tumors (n = 23; 64%) or testicular microlithiasis and fibrosis concerning for regressed germ cell tumor (n = 7; 19%) were found in 83% of the patients (n = 30). In 2 patients, lymph node biopsy diagnosed metastatic lung adenocarcinoma in one and chronic lymphocytic leukemia in the other. Initial brain magnetic resonance imaging revealed T2 hyperintensities in the temporal lobe (n = 12), cerebellum (n = 9), brainstem (n = 3), or diencephalon (n = 3). Among KLHL11 IgG+ patients who underwent HLA class I and class II genotyping (n = 10), most were found to have HLA-DQB1*02:01 (n = 7; 70%) and HLA-DRB1*03:01 (n = 6; 60%) associations. A biopsied gadolinium-enhancing temporal lobe lesion demonstrated T cell-predominant inflammation and nonnecrotizing granulomas. Cerebellar biopsy (patient with chronic ataxia) and 2 autopsied brains demonstrated Purkinje neuronal loss and Bergmann gliosis, supporting early active inflammation and later extensive neuronal loss. Compared with nonautoimmune control peripheral blood mononuclear cells, cluster of differentiation (CD) 8+ and CD4+ T cells were significantly activated when patient peripheral blood mononuclear cells were cultured with KLHL11 protein. Most patients (58%) benefitted from immunotherapy and/or cancer treatment (neurological disability stabilized [n = 10] or improved [n = 9]). Kaplan-Meier curve demonstrated significantly higher probability of wheelchair dependence among patients without detectable testicular cancer. Long-term outcomes in KLHL11-IgG+ patients were similar to Ma2 encephalitis., Conclusions and Relevance: Kelch-like protein-11 IgG is a biomarker of testicular germ-cell tumor and paraneoplastic neurologic syndrome, often refractory to treatment. Described expanded neurologic phenotype and paraclinical findings may aid in its early diagnosis and treatment.

The recent discovery of several neuronal autoantibodies linked to neurologic syndromes that are fully or partially responsive to immunosuppressive therapy has revolutionized neuroimmunology and expanded the scope of classical paraneoplastic and antibody-related syndromes. A great deal of understanding of the techniques of neuronal antibody testing, the sensitivity and specificity of serum and cerebrospinal fluid sampling, and the value of the specific type and titer of each antibody is imperative. This article provides an overview of neuronal antibody and paraneoplastic panel testing with emphasis on how to differentiate clinically relevant from clinically irrelevant results and the downstream implications of those results., Competing Interests: Disclosure Dr H. Abboud is a consultant for Biogen, Genentech, Sanofi Genzyme, Celgene, Alexion, and Viela Bio. He receives research support from Novartis, Genentech, and Celgene. The other authors have nothing to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To determine the observed and expected incidence rates of paraneoplastic neurologic syndromes (PNSs) and autoimmune encephalitides (AEs) diagnosed in France between 2016 and 2018, we conducted a population-based epidemiologic study., Methods: Observed incidence rates were stratified by sex, age groups, region of care, year of diagnosis, and disease subgroups. National expected incidence rates were calculated based on rates obtained in the area directly adjacent to the Reference Center using a mixed Poisson model and compared with observed incidence rates., Results: Six hundred thirty-two patients with definite PNS or AE met the inclusion criteria. The observed incidence rate of definite PNS and AE in France was 3.2 per million person-years (CI 95% : 2.9-3.4) compared with an expected incidence rate of 7.1 per million person-years (CI 95% : 3.9-11.4). The national observed incidence rate for the antibody-positive AE subgroup increased from 1.4 per million person-years (CI 95% : 1.2-1.7) in 2016 to 2.1 per million person-years (CI 95% : 1.7-2.4) in 2018, thus surpassing the incidence rate of classical PNS (1.2 per million person-years [CI 95% : 1.0-1.5]) of 2018., Conclusions: There was a significant widespread year-to-year increase in the incidence of diagnoses registered with the Reference Center for all subgroups of PNS and AE studied. The national observed incidence rate is likely underestimated due to underdiagnosis and underreporting., (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

A 66-year-old woman with small-cell lung cancer and cancer-associated retinopathy with anti-recoverin antibodies presented with subacute paraplegia associated with recurrence of lung cancer. Although a spinal cord MRI did not show any visible lesion, the neurological symptoms and cerebrospinal fluid findings indicated myelitis. Anti-CV2/CRMP5 antibodies were also positive and the patient was diagnosed with paraneoplastic myelopathy. After medication with prednisolone, her neurological symptoms improved and she survived over three years without recurrence of neurological symptoms. In general, paraneoplastic myelopathy is refractory against immunotherapy but in this case, immunotherapy was successful and resulted in long-term survival. We recommend examining anti-neuronal antibodies and choose and continue the appropriate immunotherapy.

Autoantibodies related to central nervous system (CNS) diseases propel research on paraneoplastic neurological syndrome (PNS). This syndrome develops autoantibodies in combination with certain neurological syndromes and cancers, such as anti-HuD antibodies in encephalomyelitis with small cell lung cancer and anti-Yo antibodies in cerebellar degeneration with gynecological cancer. These autoantibodies have roles in the diagnosis of neurological diseases and early detection of cancers that are usually occult. Most of these autoantibodies have no pathogenic roles in neuronal dysfunction directly. Instead, antigen-specific cytotoxic T lymphocytes are thought to have direct roles in neuronal damage. The recent discoveries of autoantibodies against neuronal synaptic receptors/channels produced in patients with autoimmune encephalomyelitis have highlighted insights into our understanding of the variable neurological symptoms in this disease. It has also improved our understanding of intractable epilepsy, atypical psychosis, and some demyelinating diseases that are ameliorated with immune therapies. The production and motility of these antibodies through the blood-brain barrier into the CNS remains unknown. Most of these recently identified autoantibodies bind to neuronal and glial cell surface synaptic receptors, potentially altering the synaptic signaling process. The clinical features differ among pathologies based on antibody targets. The investigation of these antibodies provides a deeper understanding of the background of neurological symptoms in addition to novel insights into their basic neuroscience.

Introduction: Encephalitis with gamma-aminobutyric acid (GABA)-B receptor antibodies (GABA-B receptor encephalitis) is known to have underlying neoplastic condition in half of the cases; however, there could be an additional event that could work as a trigger factor. Here, we report a patient with GABA-B receptor encephalitis associated with small cell lung cancer, which was probably triggered by enterovirus encephalitis., Case Report: A 53-year-old man was admitted for a seizure, following fever and headache for 3 days. Status epilepticus developed on the following day. Brain magnetic resonance imaging (MRI) was normal. Cerebrospinal fluid (CSF) study revealed lymphocyte-dominant pleocytosis, and enterovirus was detected by polymerase chain reaction test in CSF later. The patient recovered after 2 weeks of treatment. Another 2 weeks later, he showed confusion and seizure without fever. Follow-up CSF study revealed no abnormalities; however, MRI showed a lesion with vasogenic edema on the right posterior hippocampus. GABA-B receptor antibodies were found in the serum and CSF. The chest computed tomography revealed a mass on his right upper lung, which was confirmed as a small cell lung cancer. GABA-B receptor encephalitis associated with small cell lung cancer was diagnosed, and intravenous immunoglobulin and methylprednisolone were infused. Following treatment, seizures and delirium stopped, and the patient recovered to a near normal state. Follow-up MRI performed 2 months later showed that the hippocampal lesion had disappeared., Conclusion: In cases of infectious encephalitis with an atypical recurrent course, the possibility of newly onset autoimmune encephalitis should be considered.

Purpose: Merkel cell carcinoma is highly sensitive to both radiation and immunotherapy. Moreover, concurrent radioimmunotherapy may capitalize on anti-tumor immune activity and improve Merkel cell treatment response, although an enhanced immune system may cross-react with native tissues and lead to significant sequelae., Methods: Here we present a case study of a patient with metastatic Merkel cell carcinoma treated with radiotherapy concurrent with pembrolizumab., Results: After radioimmunotherapy, the patient developed sensory neuropathy, visual hallucinations, and mixed motor neuron findings. Neurologic dysfunction progressed to profound gastrointestinal dysmotility necessitating parenteral nutrition and intubation with eventual expiration., Conclusion: This case represents a unique autoimmune paraneoplastic neurologic syndrome, likely specific to neuroendocrine tumors and motivated by concurrent radioimmunotherapy. Recognition of the potential role of radioimmunotherapy may provide an advantage in anticipating these severe sequelae.

Background: Myelin oligodendrocyte glycoprotein (MOG) is an important marker on the surface of oligodendrocytes and is associated with many demyelinating diseases. Recently, MOG-IgG-associated encephalomyelitis (MOG-EM) has been proposed as a disease entity with a preliminary diagnosis standard. Some patients with lung cancer have been reported to be seropositive for onconeural antibodies; however, lung cancer cases with MOG-EM have not been previously reported., Methods: We report the case of a patient with lung adenocarcinoma with multiple intracranial lesions found during molecular targeted therapy., Results: The patient tested positive for MOG antibody in her cerebrospinal fluid, and the therapeutic effect of steroids was excellent., Conclusion: This is the first reported case of MOG-EM coincident with lung cancer in a patient with multiple intracranial lesions. When patients present with a history of malignant tumors or suspected paraneoplastic neurological syndrome, clinicians should also be alert to the presence of other autoimmune antibodies such as MOG-IgG to avoid treatment delay., Competing Interests: Decalartion of Competing interest The authors declare that they have no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Anti-GAD65 antibodies have been identified in both acute/subacute seizures (limbic encephalitis and extralimbic encephalitis) and chronic isolated epilepsy. The evidence of high serum titers and intrathecal synthesis play a fundamental role in diagnosis but poorly correlate with disease severity or response to therapies. It remains controversial whether anti-GAD65 Abs are the pathogenic entity or only serve as a surrogate marker for autoimmune disorders mediated by cytotoxic T cells. Unlike other immune-mediated epilepsy, although multiple combinations of therapeutics are used, the efficacy and prognosis of patients with GAD65-epilepsy patients are poor. Besides, GAD65-epilepsy is more prone to relapse and potentially evolve into a more widespread CNS inflammatory disorder. This article reviews the recent advances of GAD65-epilepsy, focusing on the diagnosis, epidemiology, pathophysiology, clinical features, and treatment, to better promote the recognition and provide proper therapy for this condition., Competing Interests: Declaration of Competing Interest None of the authors has any conflict of interest to disclose., (Copyright © 2020 Elsevier B.V. All rights reserved.)