Diagnosis Of Paraneoplastic Neurological Syndromes Research Articles

Management of Paraneoplastic Syndromes in the Era of Immune Checkpoint Inhibitors.

Our understanding of paraneoplastic neurologic syndromes (PNS) has blossomed over the past few decades. Clinicians have access to more robust diagnostic criteria and have a heightened index of suspicion for these disorders. Nonetheless, treatment, which typically includes immunosuppression, and response to treatment, varies. Due to persistent difficulty in making a definitive diagnosis, we favor empiric treatment when a possible diagnosis of PNS is suspected, and other alternative causes have substantially been excluded (e.g., infections, toxic-metabolic derangements, metastasis, or leptomeningeal disease). Treatment of the underlying cancer, if identified, is the first therapeutic step and can prevent disease worsening and in rare cases, can reverse neurologic symptoms. In addition to anti-cancer treatment, first line immunotherapies, which include corticosteroids, intravenous immunoglobulins (IVIG), or plasma exchange (PLEX) are typically used. If partial or no benefit is seen, second line immunotherapeutic agents such as rituximab are considered. Additionally, the severity of the initial presentation and possible risk for relapse influences the use of the latter agents. Symptomatic management is also an important component in our practice and will depend on the syndrome being treated. One of the more novel entities we are facing currently is the management of immune checkpoint (ICI)-induced PNS. In those cases, current American Society of Clinical Oncology (ASCO) guidelines are followed.

Anti-Ma2 Antibody-Mediated Paraneoplastic Cerebellar Degeneration and Myeloneuropathy Secondary to Lymphoma.

A 61-year-old woman with a history of untreated low-grade B-cell lymphoma presented with blurry vision, unsteadiness, and worsening pain on touching skin of the upper trunk was enrolled. Blurry vision was attributed to oscillopsia from downbeat nystagmus, which later evolved into macrosaccadic oscillations. MRI brain and spine showed mild, longitudinally extensive T2 hyperintensity in the central gray matter of the spinal cord extending from the medulla to T11 level. Serum paraneoplastic panel was negative; however, she had very high titers of anti-Ma2 antibodies in cerebrospinal fluid. The diagnosis of paraneoplastic neurological syndrome was made. Empiric treatment with high dose of intravenous steroids followed by intravenous immunoglobulin infusions did not improve her symptoms. An extensive search for an underlying tumor commenced and was initially unrevealing. However, two-month follow-up positron emission tomography scan showed increased uptake in a right pulmonary nodule, which when biopsied confirmed diagnosis of extranodal marginal zone lymphoma. The final diagnosis was anti-Ma2 antibody-mediated paraneoplastic cerebellar degeneration and myeloneuropathy secondary to lymphoma.

Algorithm to improve the diagnosis of paraneoplastic neurological syndromes associated with SOX1 antibodies.

SOX1 antibodies (SOX1-abs) are associated with paraneoplastic neurological syndromes (PNS) and small cell lung cancer (SCLC). In many clinical laboratories SOX1-abs are determined by commercial line blots without confirmation by cell-based assay (CBA) with HEK293 cells expressing SOX1. However, the diagnostic yield of commercial line blots is low and the accessibility to the CBA, that is not commercially available, limited. Here, we evaluated if the addition of the band intensity data of the line blot and the immunoreactivity in a tissue-based assay (TBA) improve the diagnostic performance of the line blot. We examined serum of 34 consecutive patients with adequate clinical information that tested positive for SOX1-abs in a commercial line blot. Samples were also assessed by TBA and CBA. SOX1-abs were confirmed by CBA in 17 (50%) patients, all (100%) had lung cancer (SCLC in 16) and 15/17 (88%) had a PNS. In the remaining 17 patients the CBA was negative and none had PNS associated with lung cancer. TBA was assessable in 30/34 patients and SOX1-abs reactivity was detected in 15/17 (88%) with positive and in 0/13 (0%) with negative CBA. Only 2 (13%) of the 15 TBA-negative patients were CBA-positive. The frequency of TBA-negative but CBA-positive increased from 10% (1/10) when the band intensity of the line blot was weak to 20% (1/5) in patients with a moderate or strong intensity band. Confirmation by CBA should be mandatory for samples (56% in this series) not assessable (4/34; 12%) or negative in the TBA (15/34; 44%).

Detection of paraneoplastic antibodies and their significance in paraneoplastic neurologic syndromes: a narrative review.

Paraneoplastic neurological syndromes (PNS) are a group of rare syndromes associated with immunopathological process and tumors. Paraneoplastic autoantibodies are important for the diagnosis of PNS and for searching for underlying tumors. With the development of detection methods and discovery of new autoantibodies, the 2004 guidelines on PNS have recently been updated by a worldwide PNS-Care expert group. For clinicians, proper testing methods and testing results explanation are important for the diagnosis and treatment of PNS. This review aims to review the detection of paraneoplastic autoantibodies and the significance of testing results. We summarize the studies on detection methods, association of autoantibodies and PNS or tumors, particularly the guidelines of PNS. Antibodies are divided into 3 groups in the context of PNS according to the frequency of cancer association regardless of their eventual pathogenic effect. Instead of well-characterized antibodies and partially-characterized antibodies, high-risk antibodies, intermediate risk antibodies and lower risk antibodies were applied. According to the location of recognized antigens, these autoantibodies are divided as anti-intracellular antigen antibodies and neuronal surface antibodies (NSAbs). Tissue-based assays is recommended as screening method for paraneoplastic antibodies. Moreover, this method is helpful to discover new autoantibodies. A combination of a screening method [tissue-based assays (TBA)] and a confirmatory test [immunoblot and cell-based assay (CBA)] can improve sensitivity and specificity of the tests. Many PNSs are associated with specific antineuronal antibodies, but there is considerable diversity. Some autoantibodies are markers of specific neurological syndromes. Paraneoplastic antibodies are often specific for the PNS-associated tumor rather than for a particular neurological syndrome. Diagnosis of PNS depends on integrated analysis of clinical manifestations and auxiliary examinations. During diagnosis, selection of candidate antibodies for testing is challenging due to the varying clinical phenotypes and tumors associated with a given antibody. Broad antibody panels are more likely to capture causative antibodies and should be considered. According to different subtypes of autoantibodies, specific tumors or PNS should be considered. However, antibody titers, including cerebrospinal fluid (CSF) titers, should not be the primary driver of treatment decisions.

An overview on CV2/CRMP5 antibody-associated paraneoplastic neurological syndromes.

Paraneoplastic neurological syndrome refers to certain malignant tumors that have affected the distant nervous system and caused corresponding dysfunction in the absence of tumor metastasis. Patients with this syndrome produce multiple antibodies, each targeting a different antigen and causing different symptoms and signs. The CV2/collapsin response mediator protein 5 (CRMP5) antibody is a major antibody of this type. It damages the nervous system, which often manifests as limbic encephalitis, chorea, ocular manifestation, cerebellar ataxia, myelopathy, and peripheral neuropathy. Detecting CV2/CRMP5 antibody is crucial for the clinical diagnosis of paraneoplastic neurological syndrome, and anti-tumor and immunological therapies can help to alleviate symptoms and improve prognosis. However, because of the low incidence of this disease, few reports and no reviews have been published about it so far. This article intends to review the research on CV2/CRMP5 antibody-associated paraneoplastic neurological syndrome and summarize its clinical features to help clinicians comprehensively understand the disease. Additionally, this review discusses the current challenges that this disease poses, and the application prospects of new detection and diagnostic techniques in the field of paraneoplastic neurological syndrome, including CV2/CRMP5-associated paraneoplastic neurological syndrome, in recent years.

Paraneoplastic Kelch-like protein 11 antibody-associated cerebellar and limbic encephalitis caused by metastatic “burned-out” seminoma – A scar(r)y phenomenon

IntroductionThe diagnosis of paraneoplastic neurologic syndromes is challenging when the primary tumor masquerades as scar tissue (i.e. “burned-out”). MethodsCase report. ResultsA 45-year-old male patient presented with progressive cerebellar symptoms and hearing loss. Initial screening for malignancy and extensive testing of paraneoplastic and autoimmune neuronal antibodies gave negative results. Repeated whole-body FDG-PET CT revealed a single paraaortic lymphadenopathy, metastasis of a regressed testicular seminoma. Anti-Kelch-like protein-11 (KLHL11) encephalitis was finally diagnosed. ConclusionOur case highlights the importance of continued efforts to find an often burned-out testicular cancer in patients with a highly unique clinical presentation of KLHL11 encephalitis.

CRMP5 Antibodies-Diagnostic Challenges.

CRMP5-associated paraneoplastic neurological syndromes (PNS) are rare, and only few studies describe larger cohorts of patients with CRMP5 antibodies. We have included 24 patients with CRMP5 antibodies and compared clinical findings with diagnostic findings from two different line assays (Ravo and Euroimmun), staining of cerebellar sections and results of a newly developed cell-based assay for detection of CRMP5 antibodies, CRMP5-CBA. We found that peripheral neuropathy and cerebellar ataxia together with lung cancer were the most common diagnoses associated with CRMP5 antibodies. CRMP5-CBA was easy to perform, identified all relevant cases for CRMP5-associated PNS and is therefore a valuable add-on for verification of CRMP5 positivity in diagnosis of PNS.

Clinical characteristics of anti-CV2 antibody-associated neurological diseases

This study reviewed the clinical data of patients who were hospitalized in the Department of Neurology of Henan Provincial People's Hospital from January 2017 to October 2020. A total of 46 patients with positive serum anti-CV2 antibody were included. The average age of the patients was (54±15) years old, with a male to female ratio of 1.88∶1. Twenty-six patients were diagnosed with paraneoplastic neurological syndrome (PNS). The most malignant tumors were thymoma, small cell lung cancer, and prostate cancer. The most common PNS included myasthenia gravis, subacute cerebellar degeneration, and subacute/chronic sensorimotor neuropathies. Twenty non-PNS patients exhibited subacute/old cerebral infarction, Parkinson's disease, Alzheimer's disease, and so on. Among them, brain magnetic resonance imaging (MRI) of 10 cases showed different degrees of white matter demyelination, some of which were accompanied by brain atrophy. The current study found that the positive predictive value of anti-CV2 antibody for the diagnosis of PNS was 56.5%, which was relatively weak. As an accompanying antibody, it may be a coincidence, and it may also be related to the involvement of family members in the pathological process of the diseases.

Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.

ObjectiveThe contemporary diagnosis of paraneoplastic neurologic syndromes (PNSs) requires an increasing understanding of their clinical, immunologic, and oncologic heterogeneity. The 2004 PNS criteria are partially outdated due to advances in PNS research in the last 16 years leading to the identification of new phenotypes and antibodies that have transformed the diagnostic approach to PNS. Here, we propose updated diagnostic criteria for PNS.MethodsA panel of experts developed by consensus a modified set of diagnostic PNS criteria for clinical decision making and research purposes. The panel reappraised the 2004 criteria alongside new knowledge on PNS obtained from published and unpublished data generated by the different laboratories involved in the project.ResultsThe panel proposed to substitute “classical syndromes” with the term “high-risk phenotypes” for cancer and introduce the concept of “intermediate-risk phenotypes.” The term “onconeural antibody” was replaced by “high risk” (>70% associated with cancer) and “intermediate risk” (30%–70% associated with cancer) antibodies. The panel classified 3 levels of evidence for PNS: definite, probable, and possible. Each level can be reached by using the PNS-Care Score, which combines clinical phenotype, antibody type, the presence or absence of cancer, and time of follow-up. With the exception of opsoclonus-myoclonus, the diagnosis of definite PNS requires the presence of high- or intermediate-risk antibodies. Specific recommendations for similar syndromes triggered by immune checkpoint inhibitors are also provided.ConclusionsThe proposed criteria and recommendations should be used to enhance the clinical care of patients with PNS and to encourage standardization of research initiatives addressing PNS.

The Diagnostic Value of Onconeural Antibodies Depends on How They Are Tested

Detection of onconeural antibodies is important because establishes a definitive diagnosis of paraneoplastic neurological syndrome (PNS). The recommended method for diagnosis of onconeural antibodies is by immunohistochemistry on rodent brain sections and confirmation of results by immunoblot. However, in many diagnostic laboratories samples are only tested with commercial line blots. In this study we inquired whether this change in diagnostic methodology (line blot alone vs. combined immunohistochemistry and line blot) would affect the results. Among 439 samples examined by immunohistochemistry and a commercial line blot (Euroimmun, Lübeck, Germany) 96 (22%) were positive by line blot, and their clinical information was reviewed. Onconeural antibodies were detected by both assays in 46/96 (48%) patients (concordant group) whereas 50 (52%) were only positive by line blot (discordant group). In the concordant group 42/46 (91%) patients had a definite diagnosis of PNS whereas in the discordant group only 4/50 (8%) had PNS (p < 0.00001). None of the 14 patients with ZIC4 antibodies and 1/13 (8%) with Yo antibodies demonstrated only by line blot had PNS. These findings show a robust diagnostic value of combined diagnostic techniques, and both should be used to demonstrate onconeural antibodies, If antibody testing is performed only with line blot assay, positive bands should be confirmed by rodent brain immunohistochemistry. For ZIC4 or Yo antibody testing, line blot positivity with negative immunohistochemistry has no diagnostic significance, and for the rest of onconeural antibodies the predictive diagnostic value is low.

Anti-Ri-associated paraneoplastic ophthalmoplegia-ataxia syndrome in a woman with breast cancer: a case report and review of the literature

BackgroundBreast cancer is the most common cancer in women. However, in the management of breast cancer, paraneoplastic neurological syndromes represent a diagnostic and therapeutic challenge. The diagnosis of paraneoplastic neurological syndromes is difficult due to the heterogeneity of symptoms, the timing of presentation, and the absence of antibodies, and it generally occurs before the diagnosis of breast cancer in 80% of patients who develop paraneoplastic neurological syndromes. We describe a 72-year-old woman with subacute ophthalmoplegia-ataxia syndrome who was subsequently diagnosed as having breast cancer and anti-Ri antibodies.Case presentationA 72-year-old post-menopausal Caucasian woman, with a positive medical history for diabetes mellitus and hypertension, presented with a 3-month onset of blurred vision, diplopia, and progressive gait disturbance. Serological tests were positive for well-characterized onconeural antibodies (anti-Ri). A whole-body computed tomography scan revealed a nodular opacity under her left nipple and axillary adenopathy. A biopsy of her left breast was performed, and histological examination showed ductal carcinoma. She underwent a superoexternal quadrantectomy with left axillary dissection. The final diagnosis showed infiltrating ductal carcinoma of the breast (T1c N1 M0, stage IIA) associated with paraneoplastic ophthalmoplegia-ataxia syndrome. At a 6-month follow-up, she showed no clinical or instrumental evidence of neoplastic recurrence with partial clinical improvement of neurological symptoms, such as ataxia and diplopia.ConclusionThe diagnosis of paraneoplastic neurological syndromes is often late, as in this patient, but treatment at an early stage may provide a good prognosis. Furthermore, this is one of several cases of an anti-Ri paraneoplastic neurological syndrome not associated with myoclonus, which reinforces the belief that opsoclonus myoclonus syndrome is not pathognomonic of the associated anti-Ri paraneoplastic neurological syndromes.

Optic neuritis as the initial clinical presentation of limbic encephalitis: a case report

BackgroundLimbic encephalitis is characterized by rapid onset of working memory deficit, mood changes, and often seizures. The condition has a strong paraneoplastic association, but not all cases are invariably due to tumors.Case presentationWe present a case of limbic encephalitis in a Chinese patient who initially presented to our hospital with optic neuritis and no other neurological symptoms. The diagnosis was made radiologically, and cognitive and neurological symptoms did not occur until 5 months later. Extensive investigations for autoimmune, infective, and neoplastic causes were all negative. A working diagnosis of paraneoplastic neurological syndrome was made, and the patient is being managed with high-dose steroid therapy according to the Optic Neuritis Treatment Trial protocol during relapses, as well as with tumor surveillance.ConclusionsThis case highlights ocular symptoms as important clues for diagnosing neurological diseases, as well as autoimmune encephalitis as an important differential diagnosis in the management of “idiopathic” optic neuritis in the Chinese population.

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.

Autoantibodies in Paraneoplastic Neurological Syndrome

Paraneoplastic neurological syndromes (PNS) are caused by immune responses against neuronal antigens expressed by the tumor. Based on the immunological pathomechanisms and responsiveness of treatments, onconeuronal antibodies are divided into two categories: 1) antibodies against neural intracellular antigens and 2) antibodies against neuronal surface or synaptic antigens. The recent discovery of onconeuronal antibodies have radically changed concepts of CNS autoimmunity, including PNS. The recognition of PNS provides a foundation for the early detection of underlying tumors and initiations of prompt treatments, which can result in substantial improvement. We here review the characteristic onconeuronal antibodies, including anti-Hu, anti-Ma2, and anti-N-methyl-D-aspartate receptor, and discuss the algorithm for the diagnosis of PNS.

The Utility of FDG-PET/CT in Clinically Suspected Paraneoplastic Neurological Syndrome: A Literature Review and Retrospective Case Series

Paraneoplastic neurological syndrome (PNS) describes a spectrum of rare, heterogeneous neurological conditions associated with an underlying malignancy. Diagnosis of PNS is inherently difficult, with frequent misdiagnosis and delay. The literature suggests an underlying immune-mediated pathophysiology, and patients are usually tested for the presence of onconeural antibodies. With direct tumor therapy being the most effective method of stabilizing patients, there is a strong emphasis on detecting underlying tumors. The sensitivity of conventional CT imaging is often inadequate in such patients. While FDG-PET imaging has already been shown to be effective at detecting these tumors, FDG-PET/CT, combining both structural and functional imaging in a single study, is a more recent technique. To study the utility of FDG-PET/CT, we conducted a systematic literature review and a retrospective study. We identified 41 patients who underwent imaging for clinically suspected PNS at the regional PET-CT and neurosciences center based at the Royal Preston Hospital between 2007 and 2014 and compared the results to conventional investigations. Five patients had FDG-PET/CT tracer avidity suspicious of malignant disease, and four of these were subsequently diagnosed with cancer. Sensitivity and specificity were calculated to be 100 and 97.3%, respectively, with positive predictive value 80% and negative predictive value 100%. This compares to a sensitivity and specificity of 50 and 100%, respectively, for CT and 50 and 89%, respectively, for onconeural antibodies. These findings are in line with previous studies and support the diagnostic accuracy of FDG-PET/CT for the detection of underlying malignancy.

PARANEOPLASTIC DAMAGE TO THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM IN BREAST CANCER: A CASE REPORT

Paraneoplastic neurological syndrome involves the concurrent development of cancer and neurologicaldiseases. Breast cancer is the second most common cancer associated with paraneoplastic damage to the central and peripheral nervous system. Autoimmune genesis of the disease is characterized by the presence of highly specific onconeural antibodies, which selectively affect neurons in the brain cord, spinal cord and spinal ganglia, and cause the onset of neurological symptoms within 2 years before cancer is detected. Six well-characterized onconeural antibodies detected in the blood serum of breast cancer patients can be used for the laboratory diagnosis of paraneoplastic neurological syndrome. Of them, anti-Hu, anti-CV2 and anti-amphiphysin antibodies cause polyneuropathy most often. Anti-Yo antibody is usually associated with cerebellar degeneration. Multiple neuronal autoantibodies can be simultaneously detected in a patient. Removal of the tumor may lead to stabilization and even partial regression of the neurological symptoms in 70 % of patients. Therefore, the surgical treatment of cancer should consider not only the tumor extension, but also the severity and progression of neurological deficit. We present a case of paraneoplastic cerebellar degeneration and paraneoplastic polyneuropathy in a 50-year-old woman with the neurological symptoms appeared 5 months before breast infiltrating ductal carcinoma was detected. The current approaches to the diagnosis of paraneoplastic neurological syndrome, as well as feasibility of radical removal of the tumor due to progression of neurological deficit were discussed.

ANNA-1 Paraneoplastic Encephalomyelitis Presenting as Rapidly Progressing Dementia in a Man With Undiagnosed Small Cell Lung Cancer

ANNA-1 Paraneoplastic Encephalomyelitis Presenting as Rapidly Progressing Dementia in a Man With Undiagnosed Small Cell Lung Cancer

Aquaporin-4 IgG autoimmune syndrome and immunoreactivity associated with thyroid cancer.

Tumor cells can express so-called onconeural antigens, which are normally restricted to mature neurons and glial cells in the CNS.1 The detection of neural-reactive immunoglobulin G (IgG) aids the diagnosis of paraneoplastic neurologic syndromes (PNS)1; however, the diagnostic utility and potential pathogenicity of autoantibodies vary between neurologic diseases. By contrast, anti-aquaporin-4 (AQP4) IgG from patients with neuromyelitis optica spectrum disorder (NMOSD) is a specific biomarker for NMOSD.2 AQP4 is the most abundant water channel in the CNS, particularly abundant on astrocytes, forming the glia limitans of the blood–brain barrier.3 There is compelling evidence that AQP4-IgG reactivity and pathogenicity is restricted to the CNS, probably through an impaired blood–brain barrier.2,3 The clinical features of NMOSD include inflammation of the optic nerve, spinal cord, and specific brain areas coinciding with sites of high AQP4 expression.2,3 Some cases of NMOSD thus far reported may reflect a paraneoplastic immune response.4 Acknowledgment: The authors thank The Lundbeck Foundation, The Region of Southern Denmark, and The University of Southern Denmark for support; and the Owens group for discussion. F.P. is supported by Bundesministerium fur Bildung und Forschung (Competence Network Multiple Sclerosis).

(18)F-FDG PET/CT in the evaluation of patients suspected of paraneoplastic neurological syndrome

This study aimed to determine the diagnostic impact of (18)F-FDG PET/CT based on the clinical features of paraneoplastic neurological syndrome (PNS). Multicenter retrospective and longitudinal study of patients with suspicion of PNS. The clinical picture was classified into classic (CS) and non-classic syndrome (NCS). After the follow-up, the definitive or possible diagnosis of PNS was established. The pictures that did not match any of the previous criteria were categorized as non-classifiable. The state of the onco-neural antibodies was studied. The PET/CT was classified as positive or negative for the detection of malignancy. The relationship between PET/CT findings and the final diagnosis was determined. The differences between variables (Pearson test X(2)) and the relationship between the results of the PET/CT and the final diagnosis were analyzed. A total of 64 patients were analyzed, classifying 30% as CS and 42% as NCS. After the follow-up, 20% and 16% of subjects were diagnosed as possible and definitive PNS, respectively. Positive onco-neural antibodies were found in 13% of the patients. A definitive diagnosis of PNS was associated with a positive PET/CT (P=.08). A significant relation between antibodies expression and final diagnosis of neoplasia (P=.04) was demonstrated. The PET/CT correctly localized malignancy in 5/7 cases of invasive cancer. The PET/CT showed a higher percentage of positive results in patients with definitive diagnosis of PNS. Despite the low prevalence of malignancy in our series, the PET/CT detected malignancy in a significant proportion of patients with invasive cancer.

18F-FDG PET/CT in the evaluation of patients suspected of paraneoplastic neurological syndrome

ObjectiveThis study aimed to determine the diagnostic impact of 18F-FDG PET/CT based on the clinical features of paraneoplastic neurological syndrome (PNS). Material and methodsMulticenter retrospective and longitudinal study of patients with suspicion of PNS.The clinical picture was classified into classic (CS) and non-classic syndrome (NCS). After the follow-up, the definitive or possible diagnosis of PNS was established. The pictures that did not match any of the previous criteria were categorised as non-classifiable. The state of the onconeural antibodies was studied.The PET/CT was classified as positive or negative for the detection of malignancy. The relationship between PET/CT findings and the final diagnosis was determined. The differences between variables (Pearson test X2) and the relationship between the results of the PET/CT and the final diagnosis was analysed. ResultsA total of 64 patients were analysed, classifying 30% as CS and 42% as NCS. After the follow-up, 20% and 16% of subjects were diagnosed as possible and definitive PNS, respectively. Positive onconeural antibodies were found in 13% of the patients.A definitive diagnosis of PNS was associated with a positive PET/CT (p=.08). A significant relation between antibodies expression and final diagnosis of neoplasia (p=.04) was demonstrated.The PET/CT correctly localised malignancy in 5/7 cases of invasive cancer. ConclusionsThe PET/CT showed a higher percentage of positive results in patients with definitive diagnosis of PNS. Despite the low prevalence of malignancy in our series, the PET/CT detected malignancy in a significant proportion of patients with invasive cancer.