Epidemiology of paraneoplastic neurologic syndromes.

Paraneoplastic neurologic syndromes (PNS), initially depicted as seemingly cryptic remote manifestations of malignancy, were first described clinically in the early 20th century, with pathophysiologic correlates becoming better elucidated in the latter half of the century. There remain many questions not only about the pathophysiology but also regarding the epidemiology of these conditions. The continuous discovery of novel autoantigens and related neurologic disease has broadened the association in classical PNS to include conditions such as paraneoplastic cerebellar degeneration. It has also brought into focus several other neurologic syndromes with a putative neoplastic association. These conditions are overall rare, making it difficult to capture large numbers of patients to study, and raising the question of whether incidence is increasing over time or improved identification is driving the increased numbers of cases. With the rise and increasing use of immunotherapy for cancer treatment, the incidence of these conditions is additionally expected to rise and may present with various clinical symptoms. As we enter an era of clinical trial intervention in these conditions, much work is needed to capture more granular data on population groups defined by socioeconomic characteristics such as age, ethnicity, economic resources, and gender to optimize care and clinical trial planning.

The association between paraneoplastic neurological syndromes (PNS) and urothelial carcinoma - A review of the literature.

Paraneoplastic neurological syndromes (PNS) are rare neurological disorders arising from malignancy-triggered autoimmunity, yet their association with urothelial carcinoma remains unclear. This systematic review intends to explore any connection, alongside patient/clinical features and management. A literature search identified 25 cases of bladder and upper tract carcinoma linked to PNS. Overall, while infrequent, a meaningful association between PNS and urothelial carcinoma was found in that 84% of cases met a 'possible'-or-'higher-likelihood' PNS diagnosis. Most cases presented with high-risk PNS phenotypes, predominantly cerebellar syndromes and encephalomyelitis/sensory neuronopathy, ∼17 months within cancer diagnosis/recurrence. Review findings suggest a female preponderance in suspected PNS despite higher male incidence of urothelial cancer. Main treatments consisted of surgery alongside chemotherapy or immunotherapeutics (IVIG and/or corticosteroids), which improved symptoms for a slight majority (60%). Ultimately, while common PNS-associated neoplasms should always first be excluded in suspected PNS, in the absence of alternative causes, urothelial carcinomas do merit clinical consideration.

Paraneoplastic Neurologic Disorders.

PURPOSE OF REVIEW: To provide an overview and highlight recent updates in the field of paraneoplastic neurologic disorders. RECENT FINDINGS: The prevalence of paraneoplastic neurologic disorders is greater than previously reported and the incidence has been rising over time, due to improved recognition in the era of antibody biomarkers. Updated diagnostic criteria that are broadly inclusive and also contain diagnostic risk for clinical presentations (high and intermediate) and diagnostic antibodies (high, intermediate, and low) have replaced the original 2004 criteria. Antibody biomarkers continue to be characterized (e.g., KLHL-11 associated with seminoma in men with brainstem encephalitis). Some paraneoplastic antibodies also provide insight into likely immunotherapy response and prognosis. The rise of immune checkpoint inhibitors as cancer therapeutics has been associated with newly observed immune-mediated adverse effects including paraneoplastic neurological disorders. The therapeutic approach to paraneoplastic neurologic disorders is centered around cancer care and trials of immune therapy. The field of paraneoplastic neurologic disorders continues to be advanced by the identification of novel antibody biomarkers which have diagnostic utility, and give insight into likely treatment responses and outcomes.

Population-Based Epidemiology Study of Paraneoplastic Neurologic Syndromes.

OBJECTIVES: Population-based epidemiologic data for paraneoplastic neurologic syndromes (PNSs) in the United States are lacking. Our objective was to evaluate the incidence, prevalence, and associated morbidity of PNS. METHODS: We performed a population-based epidemiology study in Olmsted County, Minnesota, with patients identified between January 1, 1987, and December 31, 2018, using the medical records linkage system of the Rochester Epidemiology Project (REP) who met the definite/probable 2021 PNS criteria and 2004 PNS criteria. Patients with dermatomyositis and myasthenia gravis with underlying tumors were included. Age- and sex-specific population counts were obtained from REP resources for January 1, 2014 (prevalence denominator) and annually for 1987-2018 (incidence denominator). Morbidity was estimated using disability-adjusted life years (DALYs; years lived with disability [YLD] plus years of life lost [YLL]). RESULTS: There were 28 patients with PNS identified (50% female) residing in Olmsted County, Minnesota, with median age at diagnosis of 54.5 (IQR 46.5-69.0) years. All patients had a cancer diagnosis, and 18 (64%) patients were neural autoantibody positive including antineuronal nuclear autoantibody type 1 (ANNA-1/anti-Hu; n = 1), ANNA-2/anti-Ri (n = 1), muscle-type acetylcholine receptor (AChR; n = 6), Purkinje cell cytoplasmic antibody type 1 (PCA-1/anti-Yo; n = 1), kelch-like protein 11 (KLH11; n = 3), collapsin response mediator protein 5 (CRMP-5/anti-CV2; n = 2), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (n = 1), neurofilament light chain (n = 1), leucine zipper 4 (LUZP4; n = 1), and unclassified neural antibodies (n = 1). PNS incidence was 0.6/100,000 person-years and increased over time from 0.4/100,000 person-years (1987-2002) to 0.8/100,000 person-years (2003-2018) (p = 0.06). Prevalence was 5.4/100,000 people. The median follow-up period after PNS diagnosis was 3.1 years (IQR, 1.1-9.9 years). Total disability-adjusted life years (DALYs) for 28 patients with PNS were 472.7 years, based on total years of life lost (YLL) for patients dying between 1987 and 2018 (n = 15) of 445.3 years plus years lived with disability (YLD) 27.4 years. DISCUSSION: PNSs are rare neurologic disorders but are associated with severe morbidity and mortality. The estimated number of prevalent PNS cases in the United States is 17,099, and predicted DALY for all US PNS cases is 292,393 years. Their apparent increasing rate of detection is attributable to increasing physician awareness and availability of serologic testing.

A single center retrospective study of paraneoplastic neurological syndromes with positive onconeural antibodies.

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.

Immunophenotypical characterization of paraneoplastic neurological syndrome patients: a multicentric study.

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.

Evaluating the frequency of positive paraneoplastic antibodies and associated malignancy risk.

OBJECTIVE: To evaluate the association between malignancy and frequently positive paraneoplastic antibodies. METHODS: A retrospective cohort study was carried out for all patients who received paraneoplastic antibody testing in 2013-2014 at a tertiary referral center. Available medical records on included patients were reviewed through July 2020. Patients were divided into antibody positive and negative subgroups. Focused analysis was performed on the subgroup of patients who received testing via a commonly used antibody panel. RESULTS: A total of 1860 patients (the full cohort) received 19,323 antibody testing via panel or individual antibody testing, and were followed-up for a mean period of 36.2 months (range 0-83 months). Altogether 229 antibodies in 196 patients were positive, and 9 (3.9%) in 7 patients were against onconeuronal antigens. The remaining 220 (96.1%) were positive for mostly antibodies against cell surface or synaptic antigens. A total of 1161 patients received Mayo Clinic paraneoplastic antibody panel tests (the panel cohort), and 14.9% (173) of these patients possessed one or more positive antibodies. For the panel cohort, no difference was found between antibody positive and negative groups with respect to the prevalence of previously existing malignancy (15.6% versus 16.6%, p = 0.745) or incidence of new malignancy (4.0% vs. 3.7%, p = 0.848) during the follow-up period. No difference was observed in the incidence of new malignancy during follow-up between the antibody positive and negative groups for the 7 most frequently positive antibodies. CONCLUSIONS: The presence of frequently positive antibodies, mostly to cell surface or synaptic antigens, is not clearly associated with the development of malignancy in the subsequent three years.

Epidemiology of paraneoplastic neurologic syndromes and autoimmune encephalitides in France.

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 (CI95%: 2.9-3.4) compared with an expected incidence rate of 7.1 per million person-years (CI95%: 3.9-11.4). The national observed incidence rate for the antibody-positive AE subgroup increased from 1.4 per million person-years (CI95%: 1.2-1.7) in 2016 to 2.1 per million person-years (CI95%: 1.7-2.4) in 2018, thus surpassing the incidence rate of classical PNS (1.2 per million person-years [CI95%: 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.

Clinical spectrum and diagnostic pitfalls of neurologic syndromes with Ri antibodies.

OBJECTIVE: To describe the main syndrome and clinical course in a large cohort of patients with anti-Ri-associated paraneoplastic neurologic syndrome (Ri-PNS). METHODS: Twenty-year retrospective nationwide study and systematic review of the literature. RESULTS: Thirty-six patients with complete clinical information were identified (median age 66 years, range: 47-87 years). In this French cohort, the majority were women (78%). At onset, 4 main patterns were observed: cerebellar syndrome (39%), isolated tremor (24%), oculomotor disturbances (17%), and other symptoms (19%). Course was multistep for 78% of cases. At the time the disease reached the plateau phase (median 12 weeks, range: 1-64 weeks; 28% >3 months), 24 (67%) showed an overt cerebellar syndrome, which was isolated in 3 patients, and was most frequently (21/24 cases) part of a multisystem neurologic disease. Patients manifested a variety of movement disorders, including myoclonus (33%), dystonia (17%), either cervical or oromandibular, and parkinsonism (17%). Most patients had cancer (92%), mainly breast cancer (n = 22). Misdiagnoses concerned 22% of patients (n = 8) and included atypical parkinsonism (n = 2), MS (n = 2), Bickerstaff encephalitis (n = 1), hyperekplexia (n = 1), vestibular neuritis (n = 1), and functional neurologic disorder (n = 1). Survival at 12 months was 73% (95% CI [0.54-0.85]), at 24 months 62% (95% CI [0.41-0.78]), and at 36 months 47% (95% CI [0.25-0.65]). There was no major clinical difference between cases retrieved from the systematic review of the literature (n = 55) and the French cohort. CONCLUSIONS: Ri-PNS is a multisystem neurologic syndrome with prominent cerebellum/brainstem involvement. Opsoclonus-myoclonus is less common than expected, and the disorder can mimic neurodegenerative diseases.

Epidemiology of paraneoplastic neurological syndromes: a population-based study.

BACKGROUND: The epidemiology of paraneoplastic neurological syndromes (PNS) remains to be defined. We present here the first population-based incidence study and report the clinical spectrum and antibody profile of PNS in a large area in Northeastern Italy. METHODS: We performed a 9-year (2009-2017) population-based epidemiological study of PNS in the provinces of Udine, Pordenone and Gorizia, in the Friuli-Venezia Giulia region (983,190 people as of January 1, 2017). PNS diagnosis and subgroups were defined by the 2004 diagnostic criteria. Age- and sex-adjusted incidence rates were calculated. RESULTS: We identified 89 patients with a diagnosis of definite PNS. Median age was 68 years (range 26-90), 52% were female. The incidence of PNS was 0.89/100,000 person-years. PNS incidence rates increased over time from 0.62/100,000 person-years (2009-2011), 0.81/100,000 person-years (2012-2014) to 1.22/100,000 person-years (2015-2017). The prevalence of PNS was 4.37 per 100,000. Most common PNS were limbic encephalitis (31%), cerebellar degeneration (28%) and encephalomyelitis (20%). Among antibody (Ab)-positive cases, most frequent specificities included: Yo (30%), Hu (26%), and Ma2 (22%), while the most frequent associated tumors were lung (17%) and breast cancer (16%), followed by lymphoma (12%). PNS developed in 1 in every 334 cancers in our region. Statistically significant associations were observed between cancer type and Ab-specificity (P < 0.001), and between neurological syndrome and Ab-specificity (P < 0.001). CONCLUSIONS: This first population-based study found an incidence of PNS that approximates 1/100,000 person-years and a prevalence of 4/100,000. Moreover, the incidence of PNS is increasing over time, probably due to increased awareness and improved detection techniques.

Paraneoplastic autoimmunity and small-cell lung cancer: Neurological and serological accompaniments.

Paraneoplastic neurological autoimmunity is often associated with small-cell lung cancer (SCLC), a highly malignant neuroendocrine tumor. Paraneoplastic autoimmunity often correlates with longer survival. We describe the paraneoplastic neurological manifestations of patients with SCLC with and without SCLC-predictive autoantibodies and the correlation between autoimmunity and survival. We reviewed the records of 116 patients (51% male) from the Mayo Clinic with histopathologically confirmed SCLC for whom stored serum was available for neural autoantibody testing. Cancer was limited stage in 41%; the median age at diagnosis was 64 years. Paraneoplastic neurological manifestations were recorded in 61% (decreasing frequency: peripheral neuropathy, dysautonomia, cognitive decline, cerebellar ataxia, neuromuscular junction disorder, seizures, cranial neuropathy, movement disorder, brainstem disorder, or myelopathy). Neural autoantibodies, some with pathogenic potential, were detected in the sera of SCLC patients with and without neurological autoimmunity. The most frequent among patients with neurological manifestations were: anti-neuronal nuclear antibody-type 1, voltage-gated calcium channel (VGCC)-N-type, VGCC-P/Q-type, glutamic acid decarboxylase 65 (GAD65), SOX1, and muscle acetylcholine receptor (AChR); while the most common in patients without neurological manifestations were: GAD65, muscle-AChR, and VGCC-P/Q-type. Neither cancer stage at diagnosis nor survival correlated with neurological manifestations or autoantibody-positivity, except for shorter survival in patients with myelopathy. The only predictor of longer survival was limited-stage disease at diagnosis.

Paraneoplastic neurological syndromes: a single institution 10-year case series.

BACKGROUND: Given its rare incidence, there are few epidemiological case series on paraneoplastic neurologic syndromes (PNS). METHODS: We present a 10-year series compiled in the Section of Neuro-Oncology, Yale Cancer Center between 2002 and 2012. RESULTS: Twenty-five cases met the PNS Euro-network criteria for definitive PNS. Most (64%; 16/25) had no known neoplasm. Cerebrospinal fluid pleocytosis declined logarithmically over time. Neuroimaging abnormalities were seen in 88% of cases (15/17), but with delayed onset. Therapeutic benefit correlated strongly to pre-treatment modified Rankin Scale (mRS) (p < 0.01), but not with time elapsed between syndrome onset to treatment (p = 0.8), first immunotherapy modality (corticosteroids: n = 10; IVIG: n = 10; PLEX: n = 3; p = 0.37), or number of immunotherapy modalities provided (p = 0.17). PNS-related mortality was high (24%; 6/25). Nonetheless, 16% (3/18; 7 living patients censored) survived over 6 times the anticipated median expected by tumor type and stage. CONCLUSIONS: PNS are rare, at an estimated incidence of 3.1 cases per million-person-years. Detection of CSF pleocytosis and MRI abnormalities depend on time of analysis. While PNS-related mortality was high, immunotherapy benefit correlated strongly with pre-treatment mRS and long-term survival is possible.

Various clinical features of patients with anti-Hu associated paraneoplastic neurological syndromes: An observational study.

To describe and analyze the clinical features and prognosis of patients with anti-Hu associated paraneoplastic neurological syndromes (PNS).The symptoms, MRI findings, cerebrospinal fluid (CSF) changes, electroencephalogram (EEG) characteristics and prognoses of 9 well-diagnosed anti-Hu associated PNS patients were analyzed.The study enrolled 6 female and 3 male patients. Three patients presented with vertigo and 6 patients exhibited a depressed mood, numbness of the lower limbs, generalized pains, seizures, mental disturbances, and a temporary unilateral hand tremor on initial presentation. Three patients presented with MRI abnormalities localized in the mesial temporal lobe and the thalamus. Abnormal interictal EEG readings were observed in all 5 patients who underwent EEG study. Four patients were found lung cancer (3 during hospitalization, 1 during follow-up). Seven patients were treated with immunotherapy and improved in symptoms. Three patients died during follow-up (2 with lung cancer).The clinical manifestation of anti-Hu associated PNS is diverse and multifocal. EEG may be more sensitive than MRI for early diagnosis of PNS. Long-term follow-up for patients with CT-negative anti-Hu associated PNS is necessary.

Onconeural Antibodies in Acute Psychiatric Inpatient Care.

Paraneoplastic neurological disorders associated with onconeural antibodies often appear with neuropsychiatric symptoms. To study the prevalence of onconeural antibodies in patients admitted to acute psychiatric inpatient care, the serum of 585 such patients was tested for antibodies targeting MOG, GLRA1B, DPPX, GRM1, GRM5, DNER, Yo, ZIC4, GAD67, amphiphysin, CV2, Hu, Ri, Ma2, and recoverin. Only one sample was positive (antirecoverin IgG). The present findings suggest that serum onconeural antibody positivity is rare among patients acutely admitted for inpatient psychiatric care. The clinical implications of this finding are discussed.

Autoimmune Encephalitides: A Broadening Field of Treatable Conditions.

BACKGROUND: Neurology has been continuously transforming by the refinement of molecular diagnostics and the development of disease-modifying treatments. The discovery of new antibody markers has elucidated the pathogenesis, provided the means of diagnostics, and offered cure or treatment for several immune-mediated neurological and neuropsychiatric disorders. The identification of pathogenic and marker autoantibodies has also facilitated defining the associated phenotypic spectra and the overlap among the phenotypes linked to individual immune markers. REVIEW SUMMARY: This survey presents the list of currently known autoimmune encephalitis entities along with the associated marker autoantibodies, highlights the phenotypic and immune pathogenic relationships, calls attention to the recently described rare syndromes, discusses the biological significance of the autoantibodies and targeted molecules, points out the potential postinfectious origin of immune pathogenesis in several of the disorders, and directs the readers to the latest diagnostic guidelines as well as to the generally used treatment approaches. CONCLUSIONS AND FUTURE DIRECTIONS: Owing to the successful and usually combined use of various methods to detect serum and cerebrospinal fluid autoantibodies on rodent brain sections, in primary neuronal cell culture, in immune precipitation, and cell-based assays, or in other antigen-specific immune assays (Western blot, enzyme-linked immunosorbent assay, and radioimmune assay), the subgroup of antibody marker-negative autoimmune encephalopathy syndromes is contracting, whereas the numbers of entities within the overall group are expanding. Recognition of the correct diagnosis is becoming increasingly rewarding not only for neurologists, but also for pediatric neurologists and psychiatrists.

Incidence and spectrum of paraneoplastic neurological syndromes: single center study.

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer. They are much less common, but are nevertheless important because they cause severe neurological morbidity and mortality. The present cases were studied to characterize the clinical features of patients of suspected PNS and to study their association with different types of tumors. In this study conducted from a super speciality teaching institute from South India, forty five (incidence-0.25%) patients were diagnosed with PNS based on the clinical data. They were subdivided into two groups patients with central nervous system (CNS) manifestations and those with neuromuscular manifestations. Immunological markers were assessed in a subset of patients. Majority of them (75.6%) were above 40 years. There was no sex predilection and a chronic presentation was common (42.2%). While more than half had involvement of peripheral nervous system (64.4%), CNS manifestations were present in 16 (35.6%) cases. Immunological markers were present in 10 out of 14 (58.8%) patients. Classic PNS was seen 22 cases (48.9%), while 23 (51.1%) were non classical. Most common tumor was lung cancer followed by myeloma and breast carcinoma. Present study construed that, in patients with neurological syndromes of unknown cause, search should be focused for occult malignancy based on the phenotype and onconeural antibodies, targeting the lung and breast in particular.

Paraneoplastic neurologic disorders in small cell lung carcinoma: A prospective study.

OBJECTIVE: To determine the frequency and range of paraneoplastic neurologic disorders (PNDs) and neuronal antibodies in small cell lung carcinoma (SCLC). METHODS: Two hundred sixty-four consecutive patients with biopsy-proven SCLC were recruited at the time of tumor diagnosis. All patients underwent full neurologic examination. Serum samples were taken prior to chemotherapy and analyzed for 15 neuronal antibodies. Thirty-eight healthy controls were analyzed in parallel. RESULTS: PNDs were quite prevalent (n = 24, 9.4%), most frequently Lambert-Eaton myasthenic syndrome (3.8%), sensory neuronopathy (1.9%), and limbic encephalitis (1.5%). Eighty-seven percent of all patients with PNDs had antibodies to SOX2 (62.5%), HuD (41.7%), or P/Q VGCC (50%), irrespective of their syndrome. Other neuronal antibodies were found at lower frequencies (GABAb receptor [12.5%] and N-type VGCC [20.8%]) or very rarely (GAD65, amphiphysin, Ri, CRMP5, Ma2, Yo, VGKC complex, CASPR2, LGI1, and NMDA receptor [all <5%]). CONCLUSIONS: The spectrum of PNDs is broader and the frequency is higher than previously appreciated, and selected antibody tests (SOX2, HuD, VGCC) can help determine the presence of an SCLC.

Purkinje cell cytoplasmic antibody type 1 (anti-Yo) autoimmunity in a child with Down syndrome.

IMPORTANCE: Purkinje cell cytoplasmic antibody type 1 (PCA-1)-IgG (or anti-Yo) is characteristically detected in women with gynecological or breast adenocarcinoma. We describe 2 unique scenarios occurring in 1 patient: PCA-1 paraneoplastic autoimmunity in a child, and a paraneoplastic neurological disorder in the context of Down syndrome. OBSERVATIONS: A child with Down syndrome and a history of adrenocortical carcinoma resected at age 1 year presented at age 7 years with cerebellar ataxia of subacute onset. Paraneoplastic serological and cerebrospinal fluid evaluations revealed PCA-1. Serological and biochemical studies also supported a diagnosis of subclinical autoimmune hypothyroidism. Extensive serum, urine, and radiological testing did not reveal a new or recurrent neoplasm. Neurological improvements after standard immunotherapy were lacking. CONCLUSIONS AND RELEVANCE: Solid organ neoplasms are uncommon among patients with Down syndrome, but organ-specific autoimmune diseases are common. In our patient, Down syndrome-related impaired T regulatory lymphocyte function (previously reported) may have resulted in both enhanced immunity against an undetected solid neoplasm and paraneoplastic neurological (PCA-1) autoimmunity.

Paraneoplastic disorders of the central and peripheral nervous systems.

Paraneoplatic neurologic syndromes (PNS) have been seminally defined as acute or subacute neurological syndromes resulting from nervous system dysfunction that is remote from the site of a malignant neoplasm or its metastases. However, in respect to our current understanding of their pathogenesis we may redefine these disorders as cancer-related dysimmune neurologic syndromes. We first deal with the epidemiology and the pathogenesis of PNS, then the different classic PNS are reviewed with clinical features according to the associated onconeuronal antibodies. Finally, therapeutic approaches are discussed.

Paraneoplastic neurological disorders in children with benign ovarian tumors.

AIM: Paraneoplastic neurological diseases (PND) are rare, but potentially treatable disorders. Paraneoplastic encephalitis is rapidly emerging as an important but likely under-recognized condition in children. The aim of this study was to assess the prevalence and spectrum of PND in children with benign ovary tumor and the long-term outcome. PATIENTS AND METHODS: We retrospectively reviewed the charts of all female patients below 18years of age diagnosed with a benign ovarian tumor proven by pathology between January 1993 and December 2010. All the clinical symptoms developed within 5years of tumor diagnosis and the related investigations were recorded. RESULTS: There were total 133 children and adolescents with benign ovarian tumors, mostly mature teratoma. Six patients (4.5%) had neuropsychiatric manifestations and all but one were beyond age 10years. The most common neuropsychiatric presentations were depression or low mood (84%), headache (50%), mutism (50%), hypoventilation (50%), seizures (30%), hallucination (30%), vomiting and hypersalivation (30%). Three patients (2.2%) had serious PND including acute disseminated encephalomyelitis in 1 and anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in 2. Although all of three improved after tumor removal, one without immunotherapy had neurological sequelae and prolonged ICU stay. CONCLUSION: The prevalence of PND in benign ovary tumor is not so uncommon in children. It is important to survey ovary tumors in female adolescents with subacute presentation of multiple-level involvement of neuraxis where no clear alternate diagnosis is possible. Treatment of serious PND associated with ovary tumors should include immunotherapy in addition to tumor removal.