Paraneoplastic disorders in thymoma patients. J Thorac Oncol. 2014;9:S143-S147. [PMID: 25396312 DOI: 10.1097/jto.0000000000000300]

Hyponatraemia: the importance of obtaining a detailed history and corroborating point-of-care analysis with laboratory testing

We describe a 67-year-old man admitted from a mental health unit with an incidental finding of hyponatraemia on routine blood tests. Laboratory investigations were in keeping with syndrome of inappropriate antidiuretic hormone secretion (SIADH). He had been recently commenced on mirtazapine. During his inpatient stay, he became increasingly confused. Review of a previous admission with hyponatraemia raised the possibility of voltage-gated potassium channel antibody-associated limbic encephalitis, although subsequent investigations deemed this unlikely as a cause of hyponatraemia. Although his sodium levels improved with fluid restriction, serial point-of-care testing proved misleading in monitoring the efficacy of treatment as inconsistencies were seen in comparison with laboratory testing. The cause of hyponatraemia may have been medication-induced SIADH and/or polydipsia. This case highlights the importance of collating detailed histories and laboratory blood testing to guide management in cases of hyponatraemia of unknown aetiology.

A systematic review of paraneoplastic syndromes associated with thymoma: Treatment modalities, recurrence, and outcomes in resected cases

OBJECTIVE

Paraneoplastic syndromes associated with thymomas remain incompletely understood. The objective was to examine the association between surgically resected thymomas and paraneoplastic syndromes over the past half century.

METHODS

A primary PubMed/MEDLINE search was used to identify published articles describing paraneoplastic syndromes associated with thymomas from 1960 to 2019. A secondary search identified additional articles referenced in the articles found in the primary search. Kaplan-Meier and log-rank test were used for time-to-event data analyses.

RESULTS

From 407 articles describing 507 patients, 123 different paraneoplastic syndromes were associated with thymoma. The 5 most common paraneoplastic syndromes were myasthenia gravis, pure red cell aplasia, lichen planus, Good syndrome, and limbic encephalitis. Complete or partial resolution of paraneoplastic syndrome symptoms after surgery was noted in 76% of patients, of whom 21% had a relapse or new paraneoplastic syndrome onset after surgery. The most common adjunctive therapy associated with resolution of paraneoplastic syndrome was corticosteroids (30%). For all patients after surgery, thymoma recurrence was observed in 17% of cases, whereas recurrence of paraneoplastic syndrome was observed in 34% of cases, and both were observed in approximately 11% of cases. The 5- and 10-year overall survivals were 78% and 66%, respectively. Improved overall survival was associated with patients who had total resolution from paraneoplastic syndrome.

CONCLUSIONS

A comprehensive assessment of publications over the past half century suggests that a multimodal treatment approach that includes surgical resection of thymomas is able to achieve paraneoplastic syndrome resolution in a majority of patients. Onset of new paraneoplastic syndromes after surgery is associated with the recurrence of the first paraneoplastic syndrome, and resolution of paraneoplastic syndrome is associated with improved overall survival.

Recurrent Thymoma-Associated Paraneoplastic Encephalitis Resulting From Multiple Antibodies: A Case Report

Few reports describe the clinical course and acute-care management of patients with recurrent multi-antibody paraneoplastic encephalitis. We describe a rare case of a patient having thymoma with multiple paraneoplastic syndromes who was found to have antibodies to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) followed by N-methyl-d-aspartate (NMDA) receptor in the setting of residual thymic tissue. He initially presented to the hospital with severe, rapidly progressive encephalitis with simultaneous antibodies to AMPA and voltage-gated potassium channel complex receptor. Brain magnetic resonance imaging revealed scattered white matter hyperintensities and an enhancing lesion adjacent to the left caudate. Computerized tomography showed an anterior mediastinal mass that was resected and revealed to be a thymoma. He was refractory to treatment with intravenous immunoglobulin, high-dose steroids, and plasmapheresis. He was then started on monthly cyclophosphamide. After 3 cyclophosphamide infusions, he began to show improvement in his alertness, ability to speak, and capacity to follow commands. One month later, he was readmitted to the hospital for new and unusual behavioral outbursts and agitation. He was found to have new anti-NMDA receptor antibodies in his cerebrospinal fluid in the setting of residual hyperplastic thymic tissue that required another resection. He was treated with rituximab and then cyclophosphamide (due to an infusion reaction with rituximab) with positive outcomes. The presence of multiple antibodies may be associated with poor prognosis, requiring prompt recognition and aggressive immunosuppressive treatment. New neurological symptoms should prompt a search for residual pathologic tissue or tumor recurrence causing new autoantibodies and additional paraneoplastic syndromes.

Thymic Small Cell Carcinoma Associated With Lambert-Eaton Myasthenic Syndrome

Thymic small cell cancer is a very rare type of thymic epithelial tumor. Lambert-Eaton myasthenic syndrome is a rare paraneoplastic syndrome associated with thymic epithelial tumors. We report an extremely rare case of Lambert-Eaton myasthenic syndrome associated with thymic small cell carcinoma. A 71-year-old man was referred to our institution for a mediastinal tumor and a 2-month history of ptosis, fatigue, and gait disorder. Based on radiologic findings thymoma associated with Lambert-Eaton myasthenic syndrome was diagnosed, and extended thymectomy was performed. After surgery the patient's symptoms had not improved. Anticholinesterase treatment alleviated his symptoms.

The role of thymic tolerance in CNS autoimmune disease

The contributions of the peripheral adaptive and innate immune systems to CNS autoimmunity have been extensively studied. However, the role of thymic selection in these conditions is much less well understood. The thymus is the primary lymphoid organ for the generation of T cells; thymic mechanisms ensure that cells with an overt autoreactive specificity are eliminated before they emigrate to the periphery and control the generation of thymic regulatory T cells. Evidence from animal studies demonstrates that thymic T cell selection is important for establishing tolerance to autoantigens. However, there is a considerable knowledge gap regarding the role of thymic selection in autoimmune conditions of the human CNS. In this Review, we critically examine the current body of experimental evidence for the contribution of thymic tolerance to CNS autoimmune diseases. An understanding of why dysfunction of either thymic or peripheral tolerance mechanisms rarely leads to CNS inflammation is currently lacking. We examine the potential of de novo T cell formation and thymic selection as novel therapeutic avenues and highlight areas for future study that are likely to make these targets the focus of future treatments.

Presence of Multiple Autoimmune Antibodies Involved in Concurrent Myositis and Myocarditis and Myasthenia Gravis Without Thymoma: A Case Report

Inflammatory myositis (IM) and myasthenia gravis (MG) are both immune disorders involving muscle. The concurrent presence of both conditions in the same patient is extremely rare and the diagnosis is important and challenging. Here, we report a case of concurrent myositis and myocarditis and MG without thymoma in a 69-year-old man with progressive proximal muscle weakness and dysphagia. As an atypical finding, the laboratory immunity assay showed the presence of multiple antibodies (acetylcholine receptor-Ab, titin-Ab, M7-Ab, smooth muscle alpha (SMA)-Ab, and citrate acid extract (CAE)-Ab). We predicted that thymoma-associated antibodies (titin-Ab, SMA-Ab, and CAE-Ab) and anti-M7 antibodies play an important role in the concurrent presence of MG and myositis and myocarditis. In this overlap case, immunotherapy was determined to be effective.

Anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor GluR2 encephalitis in a myasthenia gravis patient with complete thymectomy: a case report

Background

Autoimmune encephalitis (AE) is a newly recognized autoimmune disorders in which the targets are proteins or receptors involved in synaptic transmission and neuronal excitability. α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is a subtype of glutamate receptor that mediates most of the fast excitatory neurotransmission in the brain.

Case presentation

A 50-year-old woman presented with subacute onset of memory loss and behavioral changes. High levels of serum (1:1000) and CSF (1:32) antibodies against the AMPAR GluR2 were detected. A wide range of abnormalities in 6–8 Hz low to middle slow waves was found by electroencephalographs, and high-intensity signals on fluid-attenuated inversion recovery in both the medial temporal lobe and hippocampus were identified on brain magnetic resonance images. This patient presented with myasthenia gravis and type B2 thymoma (World Health Organization Thymoma Classification) at age 48. This case was unique in that the patient initiated with the symptom of myasthenia gravis and thymoma two years prior to encephalitis, and a complete thymectomy was performed before AE onset without recurrence of the thymoma when encephalitis occurred.

Conclusions

Thymoma was reported to be associated with paraneoplastic neurological disease. This is the first time a thymectomy has been applied in a myasthenia gravis patient with thymoma two years prior to the onset of anti-AMPAR2 encephalitis. This case highlights the complexity of autoimmune encephalitis associated with thymoma.

Review of paraneoplastic syndromes in children

Paraneoplastic syndromes are defined as clinical syndromes that are not related to direct tumor invasion or compression but are secondary to tumor secretion of functional peptides/hormones or related to immune cross-reactivity with normal host tissue. Paraneoplastic syndromes have a wide range of presentations and can present before the primary malignancy or tumor recurrence is diagnosed. They can mimic non-neoplastic processes, making detection, diagnosis and treatment difficult. However, they can also provide clues to the presence of an underlying malignancy. In this paper, we reviewed a range of paraneoplastic syndromes that can occur in children including: (1) neurologic (opsoclonus-myoclonus, limbic, anti-N-methyl-d-aspartate [NMDA] and anti-Ma2 encephalitis and myasthenia gravis); (2) endocrine (neuroendocrine tumors, hypercalcemia, SIADH [syndrome of inappropriate antidiuretic hormone secretion], osteomalacia/rickets and ROHHAD [rapid onset of obesity, hypoventilation, hypothalamic dysfunction and autonomic dysregulation]); and (3) dermatologic/rheumatologic syndromes (hypertrophic osteoarthropathy and paraneoplastic pemphigus). Familiarity with these syndromes can aid in early diagnosis, treatment and imaging optimization.

Non-Myasthenia Gravis Immune Syndromes and the Thymus: Is There a Role for Thymectomy?

Thymectomy has long been considered, performed, and discussed for many different nonmyasthenic immune syndromes. Thymectomy is now an established treatment for MG, and has been performed for other immune syndromes with varying degrees of improvement. Although numerous reports document immune syndromes' association with thymoma, few address the role of thymectomy in symptom resolution. This review assesses thymectomy in the various nonmyasthenic immune syndromes for which it has been tried. Based on this review, it seems appropriate to revisit a more active role for thymectomy in pure red cell aplasia, pemphigus, rheumatoid arthritis, autoimmune hemolytic anemia, and ulcerative colitis.

Clinical and laboratory features of seventy-eight UK patients with Good's syndrome (thymoma and hypogammaglobulinaemia)

Good’s syndrome (thymoma and hypogammaglobulinaemia) is a rare secondary immunodeficiency disease, previously reported in the published literature as mainly individual cases or small case series. We use the national UK‐Primary Immune Deficiency (UKPID) registry to identify a large cohort of patients in the UK with this PID to review its clinical course, natural history and prognosis. Clinical information, laboratory data, treatment and outcome were collated and analysed. Seventy‐eight patients with a median age of 64 years, 59% of whom were female, were reviewed. Median age of presentation was 54 years. Absolute B cell numbers and serum immunoglobulins were very low in all patients and all received immunoglobulin replacement therapy. All patients had undergone thymectomy and nine (12%) had thymic carcinoma (four locally invasive and five had disseminated disease) requiring adjuvant radiotherapy and/or chemotherapy. CD4 T cells were significantly lower in these patients with malignant thymoma. Seventy‐four (95%) presented with infections, 35 (45%) had bronchiectasis, seven (9%) chronic sinusitis, but only eight (10%) had serious invasive fungal or viral infections. Patients with AB‐type thymomas were more likely to have bronchiectasis. Twenty (26%) suffered from autoimmune diseases (pure red cell aplasia, hypothyroidism, arthritis, myasthenia gravis, systemic lupus erythematosus, Sjögren’s syndrome). There was no association between thymoma type and autoimmunity. Seven (9%) patients had died. Good’s syndrome is associated with significant morbidity relating to infectious and autoimmune complications. Prospective studies are required to understand why some patients with thymoma develop persistent hypogammaglobulinaemia.

Best practices for the management of thymic epithelial tumors: A position paper by the Italian collaborative group for ThYmic MalignanciEs (TYME)

Thymic epithelial tumors (TETs) are a heterogenous group of rare tumors, with a complex histopatological classification. Furthermore, the recent introduction of the first TNM staging system, that is scheduled to replace the Masaoka-Koga system, may create further difficulties in TET management, that remains challenging. Several guidelines for treatment of TETs are available and provide recommendations based mainly on non randomized trials and retrospective or limited series. Often the lack of evidence leads to formulation of indications based on expert opinions. As for other rare cancers it is crucial to create networks to coordinate the work among centres involved in treatment of these diseases in order to offer the best diagnostic and therapeutic tools. For this purpose, in 2014 a network named TYME (ThYmic MalignanciEs), was founded in Italy with the aim of improving care and research in TETs. In September 2017 a panel of multidisciplinary experts from TYME network and from other Italian centres strongly involved in TET diagnosis and treatment convened a first Italian Expert meeting together with representatives of association for patients affected by rare thoracic cancers Tu.To.R, to explore how these tumors are managed in the different centres of Italy compared to ESMO guidelines. In this paper we summarize the issues discussed during that meeting and we propose recommandations based on Masaoka Koga and the new TNM staging system.

Morvan's syndrome-is a pathogen behind the curtain?

Morvan's syndrome is a rare syndrome of likely autoimmune etiology characterized by peripheral nerve hyperexcitability, dysautonomia, insomnia, and fluctuating delirium with prominent hallucinations. Since its first mention in 1890, less than 100 cases have been described in literature. The largest existing review includes details of 29 cases. This case series describes 4 cases (M = 4) of Morvan's syndrome which presented between May and November 2017 to a single tertiary care referral teaching hospital in north India. All the four patients manifested behavioral abnormalities, sleep disturbances, hallucinations, autonomic dysfunction, and clinical signs of peripheral nerve hyperexcitability, mostly as myokymia. Two of the patients had Anti-CASPR2 (contactin-associated protein 2) antibodies. Three of them had electromyography features of peripheral nerve hyperexcitability and only one had elevated cerebrospinal fluid protein level. We hypothesize that Morvan's syndrome and other less characterized autoimmune encephalitis/peripheral nervous system syndromes may have infectious triggers. A possible viral trigger may result in generation of autoantibodies which result in the typical manifestations. We base these hypotheses on the finding of four cases of an orphan disease within a short period of time in a limited geographical distribution.

Paraneoplastic Syndromes and Thymic Malignancies: An Examination of the International Thymic Malignancy Interest Group Retrospective Database

INTRODUCTION

Thymic epithelial tumors (TETs) are associated with paraneoplastic/autoimmune (PN/AI) syndromes. Myasthenia gravis is the most common PN/AI syndrome associated with TETs.

METHODS

The International Thymic Malignancy Interest Group retrospective database was examined to determine (1) baseline and treatment characteristics associated with PN/AI syndromes and (2) the prognostic role of PN/AI syndromes for patients with TETs. The competing risks model was used to estimate cumulative incidence of recurrence (CIR) and the Kaplan-Meier method was used to calculate overall survival (OS). A Cox proportional hazards model was used for multivariate analysis.

RESULTS

A total of 6670 patients with known PN/AI syndrome status from 1951 to 2012 were identified. PN/AI syndromes were associated with younger age, female sex, thymoma histologic type, earlier stage, and an increased rate of total thymectomy and complete resection status. There was a statistically significant lower CIR in the group with a PN/AI syndrome than in the group without a PN/AI syndrome (10-year CIR 17.3% versus 21.2%, respectively [p = 0.0003]). The OS was improved in the group with a PN/AI syndrome compared to the group without a PN/AI syndrome (median OS 21.6 years versus 17.0 years, respectively [hazard ratio = 0.63, 95% confidence interval: 0.54-0.74, p < 0.0001]). However, in the multivariate model for recurrence-free survival and OS, PN/AI syndrome was not an independent prognostic factor.

DISCUSSION

Previously, there have been mixed data regarding the prognostic role of PN/AI syndromes for patients with TETs. Here, using the largest data set in the world for TETs, PN/AI syndromes were associated with favorable features (i.e., earlier stage and complete resection status) but were not an independent prognostic factor for patients with TETs.

Thymoma-associated panencephalitis: a newly emerging paraneoplastic neurologic syndrome

Recently, a few case reports of thymoma-associated panencephalitis (TAPE) have brought to light a disease entity that has not been fully characterized. Literature review of TAPE reveals an array of associated neuronal antibodies, with varied responses to thymomectomy with or without immunotherapy. This report describes a case of TAPE and proposes that the GABA_A receptor antibody is a potential target antigen driving the immune process in this disease entity. Treatment-wise, early thymomectomy consistently improves the overall course of disease. Further study of such cases will be critical in clarifying the mechanisms of disease, improving early diagnosis, and developing targeted approaches to treatment.

Netrin-1 receptor antibodies in thymoma-associated neuromyotonia with myasthenia gravis

OBJECTIVE

To identify cell-surface antibodies in patients with neuromyotonia and to describe the main clinical implications.

METHODS

Sera of 3 patients with thymoma-associated neuromyotonia and myasthenia gravis were used to immunoprecipitate and characterize neuronal cell-surface antigens using reported techniques. The clinical significance of antibodies against precipitated proteins was assessed with sera of 98 patients (neuromyotonia 46, myasthenia gravis 52, thymoma 42; 33 of them with overlapping syndromes) and 219 controls (other neurologic diseases, cancer, and healthy volunteers).

RESULTS

Immunoprecipitation studies identified 3 targets, including the Netrin-1 receptors DCC (deleted in colorectal carcinoma) and UNC5A (uncoordinated-5A) as well as Caspr2 (contactin-associated protein-like 2). Cell-based assays with these antigens showed that among the indicated patients, 9 had antibodies against Netrin-1 receptors (7 with additional Caspr2 antibodies) and 5 had isolated Caspr2 antibodies. Only one of the 219 controls had isolated Caspr2 antibodies with relapsing myelitis episodes. Among patients with neuromyotonia and/or myasthenia gravis, the presence of Netrin-1 receptor or Caspr2 antibodies predicted thymoma (p < 0.05). Coexisting Caspr2 and Netrin-1 receptor antibodies were associated with concurrent thymoma, myasthenia gravis, and neuromyotonia, often with Morvan syndrome (p = 0.009). Expression of DCC, UNC5A, and Caspr2 proteins was demonstrated in paraffin-embedded thymoma samples (3) and normal thymus.

CONCLUSIONS

Antibodies against Netrin-1 receptors (DCC and UNC5a) and Caspr2 often coexist and associate with thymoma in patients with neuromyotonia and myasthenia gravis.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that antibodies against Netrin-1 receptors can identify patients with thymoma (sensitivity 21.4%, specificity 100%).

Fatal Morvan Syndrome Associated With Myasthenia Gravis

INTRODUCTION

Morvan syndrome is a rare and complex autoimmune disorder affecting multiple sites of neuraxis.

CASE REPORT

We present fulminant Morvan syndrome, developing on a background of chronic myasthenia gravis. A 54-year-old gentleman presented with fluctuating ophthalmoplegia and proximal muscles weakness of 7 years duration that remitted with pyridostigmine and prednisolone. He developed insomnia of 2 months duration, worsening of myasthenic symptoms and respiratory distress, dysautonomia, encephalopathy, and peripheral nerve hyperexcitability. Antibodies against contactin-associated protein (CASPR) 2 were detected in serum. Computed tomography of thorax showed a thymic mass. He received intravenous methyl prednisolone and plasmapheresis. Antibodies against CASPR and thymic lesion reduced with immunotherapy. However, he developed persistent hypotension and expired after 11 weeks of hospital stay.

CONCLUSIONS

Clinical clues for diagnosis of Morvan syndrome and therapeutic changes faced by the treating team are highlighted in this report. Increased awareness and prompt testing for CASPR2 antibody is warranted so that early immunotherapy can be initiated.

Myf5 and Myogenin in the development of thymic myoid cells - Implications for a murine in vivo model of myasthenia gravis

Myasthenia gravis (MG) is caused by autoantibodies against the neuromuscular junction of striated muscle. Most MG patients have autoreactive T- and B-cells directed to the acetylcholine receptor (AChR). To achieve immunologic tolerance, developing thymocytes are normally eliminated after recognition of self-antigen-derived peptides. Presentation of muscle-specific antigens is likely achieved through two pathways: on medullary thymic epithelial cells and on medullary dendritic cells cross-presenting peptides derived from a unique population of thymic myoid cells (TMC). Decades ago, it has been hypothesized that TMC play a key role in the induction of immunological tolerance towards skeletal muscle antigens. However, an experimental model to address this postulate has not been available. To generate such a model, we tested the hypothesis that the development of TMC depends on myogenic regulatory factors. To this end, we utilized Myf5-deficient mice, which lack the first wave of muscle cells but form normal skeletal muscles later during development, and Myogenin-deficient mice, which fail to form differentiated myofibers. We demonstrate for the first time that Myf5- and Myogenin-deficient mice showed a partial or complete, respectively, loss of TMC in an otherwise regularly structured thymus. To overcome early postnatal lethality of muscle-deficient, Myogenin-knockout mice we transplanted Myogenin-deficient fetal thymuses into Foxn1(nu/nu) mice that lack their own thymus anlage. We found that the transplants are functional but lack TMC. In combination with established immunization strategies (utilizing AChR or Titin), this model should enable us in the future testing the hypothesis that TMC play an indispensable role in the development of central tolerance towards striated muscle antigens.

Paraneoplastic Neurological Syndromes and Glutamic Acid Decarboxylase Antibodies

IMPORTANCE

Little is known of glutamic acid decarboxylase antibodies (GAD-abs) in the paraneoplastic context. Clinical recognition of such cases will lead to prompt tumor diagnosis and appropriate treatment.

OBJECTIVE

To report the clinical and immunological features of patients with paraneoplastic neurological syndromes (PNS) and GAD-abs.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective case series study and immunological investigations conducted in February 2014 in a center for autoimmune neurological disorders. Fifteen cases with GAD65-abs evaluated between 1995 and 2013 who fulfilled criteria of definite or possible PNS without concomitant onconeural antibodies were included in this study.

MAIN OUTCOMES AND MEASURES

Analysis of the clinical records of 15 patients and review of 19 previously reported cases. Indirect immunofluorescence with rat hippocampal neuronal cultures and cell-based assays with known neuronal cell-surface antigens were used. One hundred six patients with GAD65-abs and no cancer served as control individuals.

RESULTS

Eight of the 15 patients with cancer presented as classic paraneoplastic syndromes (5 limbic encephalitis, 1 paraneoplastic encephalomyelitis, 1 paraneoplastic cerebellar degeneration, and 1 opsoclonus-myoclonus syndrome). When compared with the 106 non-PNS cases, those with PNS were older (median age, 60 years vs 48 years; P = .03), more frequently male (60% vs 13%; P < .001), and had more often coexisting neuronal cell-surface antibodies, mainly against γ-aminobutyric acid receptors (53% vs 11%; P < .001). The tumors more frequently involved were lung (n = 6) and thymic neoplasms (n = 4). The risk for an underlying tumor was higher if the presentation was a classic PNS, if it was different from stiff-person syndrome or cerebellar ataxia (odds ratio, 10.5; 95% CI, 3.2-34.5), or if the patient had coexisting neuronal cell-surface antibodies (odds ratio, 6.8; 95% CI, 1.1-40.5). Compared with the current series, the 19 previously reported cases had more frequent stiff-person syndrome (74% vs 13%; P = .001) and better responses to treatment (79% vs 27%; P = .005). Predictors of improvement in the 34 patients (current and previously reported) included presentation with stiff-person syndrome and the presence of a thymic tumor.

CONCLUSIONS AND RELEVANCE

Patients with GAD-abs must be screened for an underlying cancer if they have clinical presentations different from those typically associated with this autoimmunity or develop classic PNS. The risk for cancer increases with age, male sex, and the presence of coexisting neuronal cell-surface antibodies.