Immunological function of thymoma and pathogenesis of paraneoplastic myasthenia gravis

Rapid growing mass of the mandible due to an oral metastasis of thymoma: Case report of an extremely rare localization and review of published cases

Background

Cancer metastases in the oral cavity are relatively uncommon, occurring in approximately 1-3% of malignant cases. Thymomas and thymic carcinomas are the two main tumors that can affect the thymus, a lymphatic gland that plays an important role in regulating the immune system. The aims of this paper are (i) to describe an extremely rare case of thymoma metastasis to the oral cavity (ii) report all published cases of thymic tumor metastases to the oral cavity.

Case report

A 62-year-old Italian male patient was referred to the Oral Medicine Department at the Fondazione Policlinico Universitario A. Gemelli - IRCCS, Rome to evaluate a rapidly growing, non-ulcerated swelling in the left buccal mucosa. After clinical examination and radiological examination, an incisional biopsy was performed under local anesthesia. Thus, a final diagnosis of intraoral metastasis of thymoma was achieve.A review of the literature of oral metastases due to thymic tumor was also conducted through a systematic search in accordance with PRISMA guidelines, via PubMed, Scopus and CENTRAL engines. Out of 328 articles retrieved, only two articles reported oral metastasis of thymic tumors; and two reports of ectopic thymic carcinoma of the parotid gland were found.

Conclusions

This paper provides a rare case of oral metastasis of thymoma. The present paper reports an almost undescribed condition. Future reports will be useful in increasing knowledge regarding this area. The oral screening of patients with thymic tumors could be useful, considering the relationship between these diseases and oral disorders.

Identification of Hub Genes and Analysis of their Regulatory miRNAs in Patients with Thymoma Associated Myasthenia Gravis Based on TCGA Database

BACKGROUND

Myasthenia gravis is an autoimmune disease, and 30% of patients with thymoma often have myasthenia gravis. Patients with thymoma-associated MG (TAMG) have many different clinical presentations compared to non-MG thymoma (NMG), yet their gene expression differences remain unclear.

OBJECTIVE

In this study, we analyzed the Differentially Expressed Genes (DEGs) and analyzed their regulatory microRNAs (miRNAs) in TAMG, which will further clarify the possible pathogenesis of TAMG.

METHODS

DEGs were calculated using the RNA-sequencing data of TAMG and NMG downloaded from The Cancer Genome Atlas (TCGA) database. R software was then used to analyze the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of DEGs, while STRING was applied to build the protein-protein interaction (PPI) network and Cytoscape to identify and visualize the hub genes. Immune infiltration significances of hub genes were also explored by using the TIMER database and TCGA database. Upstream microRNAs (miRNAs) of the hub genes were predicted by online software.

RESULTS

We comparatively analyzed the gene expression differences between TAMG and NMG groups. A total of 977 DEGs were identified between the two groups (|log fold change (FC)| >2, adjusted P value <0.050), with 555 down-regulated genes and 422 up-regulated genes. Five top hub genes (CTNNB1, EGFR, SOX2, ERBB2, and EGF) were recognized in the PPI network. Analysis based on the TIMER and TCGA databases suggested that 5 hub genes were correlated with multiple immune cell infiltrations and immune checkpoint-related markers, such as PDCD1, CTLA-4, and CD274, in TAMG patients. Lastly, 5 miRNAs were identified to have the potential function of regulating the hub gene expression.

CONCLUSION

Our study identified 5 hub genes (CTNNB1, EGFR, SOX2, ERBB2, and EGF) and their 5 regulatory miRNAs in TAMG, and the hub genes were correlated with multiple immune cell infiltrations and immune checkpoint-related markers. Our findings could help partially clarify the pathophysiology of TAMG, which could be new potential targets for subsequent clinical immunotherapy.

Identification of Potential Key Genes for the Comorbidity of Myasthenia Gravis With Thymoma by Integrated Bioinformatics Analysis and Machine Learning

Background

Thymoma is a key risk factor for myasthenia gravis (MG). The purpose of our study was to investigate the potential key genes responsible for MG patients with thymoma.

Methods

We obtained MG and thymoma dataset from GEO database. Differentially expressed genes (DEGs) were determined and functional enrichment analyses were conducted by R packages. Weighted gene co-expression network analysis (WGCNA) was used to screen out the crucial module genes related to thymoma. Candidate genes were obtained by integrating DEGs of MG and module genes. Subsequently, we identified several candidate key genes by machine learning for diagnosing MG patients with thymoma. The nomogram and receiver operating characteristics (ROC) curves were applied to assess the diagnostic value of candidate key genes. Finally, we investigated the infiltration of immunocytes and analyzed the relationship among key genes and immune cells.

Results

We obtained 337 DEGs in MG dataset and 2150 DEGs in thymoma dataset. Biological function analyses indicated that DEGs of MG and thymoma were enriched in many common pathways. Black module (containing 207 genes) analyzed by WGCNA was considered as the most correlated with thymoma. Then, 12 candidate genes were identified by intersecting with MG DEGs and thymoma module genes as potential causes of thymoma-associated MG pathogenesis. Furthermore, five candidate key genes (JAM3, MS4A4A, MS4A6A, EGR1, and FOS) were screened out through integrating least absolute shrinkage and selection operator (LASSO) regression and Random forest (RF). The nomogram and ROC curves (area under the curve from 0.833 to 0.929) suggested all five candidate key genes had high diagnostic values. Finally, we found that five key genes and immune cell infiltrations presented varying degrees of correlation.

Conclusions

Our study identified five key potential pathogenic genes that predisposed thymoma to the development of MG, which provided potential diagnostic biomarkers and promising therapeutic targets for MG patients with thymoma.

Non-Coding RNAs in Myasthenia Gravis: From Immune Regulation to Personalized Medicine

Myasthenia gravis (MG) is an antibody-mediated autoimmune disorder characterized by altered neuromuscular transmission, which causes weakness and fatigability in the skeletal muscles. The etiology of MG is complex, being associated with multiple genetic and environmental factors. Over recent years, progress has been made in understanding the immunological alterations implicated in the disease, but the exact pathogenesis still needs to be elucidated. A pathogenic interplay between innate immunity and autoimmunity contributes to the intra-thymic MG development. Epigenetic changes are critically involved in both innate and adaptive immune response regulation. They can act as (i) pathological factors besides genetic predisposition and (ii) co-factors contributing to disease phenotypes or patient-specific disease course/outcomes. This article reviews the role of non-coding RNAs (ncRNAs) as epigenetic factors implicated in MG. Particular attention is dedicated to microRNAs (miRNAs), whose expression is altered in MG patients' thymuses and circulating blood. The long ncRNA (lncRNA) contribution to MG, although not fully characterized yet, is also discussed. By summarizing the most recent and fast-growing findings on ncRNAs in MG, we highlight the therapeutic potential of these molecules for achieving immune regulation and their value as biomarkers for the development of personalized medicine approaches to improve disease care.

Autoimmunity in thymic epithelial tumors: a not yet clarified pathologic paradigm associated with several unmet clinical needs

Thymic epithelial tumors (TETs) are rare mediastinal cancers originating from the thymus, classified in two main histotypes: thymoma and thymic carcinoma (TC). TETs affect a primary lymphoid organ playing a critical role in keeping T-cell homeostasis and ensuring an adequate immunological tolerance against "self". In particular, thymomas and not TC are frequently associated with autoimmune diseases (ADs), with Myasthenia Gravis being the most common AD present in 30% of patients with thymoma. This comorbidity, in addition to negatively affecting the quality and duration of patients' life, reduces the spectrum of the available therapeutic options. Indeed, the presence of autoimmunity represents an exclusion criteria for the administration of the newest immunotherapeutic treatments with checkpoint inhibitors. The pathophysiological correlation between TETs and autoimmunity remains a mystery. Several studies have demonstrated the presence of a residual and active thymopoiesis in adult patients affected by thymomas, especially in mixed and lymphocytic-rich thymomas, currently known as type AB and B thymomas. The aim of this review is to provide the state of art in regard to the histological features of the different TET histotype, to the role of the different immune cells infiltrating tumor microenvironments and their impact in the break of central immunologic thymic tolerance in thymomas. We discuss here both cellular and molecular immunologic mechanisms inducing the onset of autoimmunity in TETs, limiting the portfolio of therapeutic strategies against TETs and greatly impacting the prognosis of associated autoimmune diseases.

Germinal centers are associated with postthymectomy myasthenia gravis in patients with thymoma

BACKGROUND AND PURPOSE

Germinal centers (GCs) can be observed in the thymic tissues of patients with thymoma-associated myasthenia gravis (MG). Although an association between thymic GCs and MG has been suggested, it is unknown whether the presence of GCs could predict the development of MG after the resection of thymoma, known as postthymectomy MG.

METHODS

We conducted a retrospective analysis of previously nonmyasthenic patients who underwent surgical removal of the thymoma. All available thymic tissue slides were rereviewed by a pathologist to assess for GCs. Patients were classified into GC-positive and GC-negative groups based on the presence of GCs. The incidence of postthymectomy MG was compared between the two groups, and the risk factors for postthymectomy MG were assessed.

RESULTS

Of the 196 previously nonmyasthenic patients who underwent thymoma resection, 21 were GC-positive, whereas 175 were GC-negative. Postthymectomy MG developed in 11 (5.6%) patients and showed a higher incidence in the GC-positive group than in the GC-negative group (33.3% vs. 2.3%, p < 0.001). No postoperative radiotherapy and the presence of GCs were risk factors for postthymectomy MG in the univariate analysis. In multivariate analysis, invasive thymoma (hazard ratio [HR] = 9.835, 95% confidence interval [CI] = 1.358-105.372), postoperative radiotherapy (HR = 0.160, 95% CI = 0.029-0.893), and presence of GCs (HR = 15.834, 95% CI = 3.742-67.000) were significantly associated with postthymectomy MG.

CONCLUSIONS

Thymic GCs may be a significant risk factor for postthymectomy MG. Even in patients with thymoma who do not show clinical symptoms of MG, postthymectomy MG should be considered, especially if thymic GCs are observed.

GTF2I mutation in micronodular thymoma with lymphoid stroma

AIMS

Micronodular thymoma with lymphoid stroma is a rare subtype of thymoma with characteristic clinical and pathological features. Some of the features, such as indolent nature, principally spindle morphology and no significant association to myasthenia gravis, are shared with type A and AB thymoma, which is closely linked to GTF2I mutation. However, not much is known regarding the molecular genetics of this thymoma subtype. In this study, the GTF2I mutation status was investigated in 16 cases of micronodular thymoma.

METHODS

16 micronodular thymomas were retrieved and the GTF2I mutation was tested by Sanger sequencing. The clinicopathological findings were documented.

RESULTS

GTF2I c.1271T>A p.(Leu424His) mutation within exon 15 was detected in 14 out of 16 tumours (87.5%). Two patients died of other causes while all others remained alive with no evidence of recurrence during the follow-up period ranging from 19 to 188 months (median: 100 months).

CONCLUSIONS

GTF2I mutation status and presence of spindle cell morphology may indicate that type A and AB thymoma, and micronodular thymoma represent a group biologically distinct from type B thymomas, which generally lack this mutation.

Paraneoplastic autoimmune neurologic disorders associated with thymoma

Thymoma is often associated with paraneoplastic neurologic diseases. Neural autoantibody testing is an important tool aiding diagnosis of thymoma and its autoimmune neurologic complications. Autoantibodies specific for muscle striational antigens and ion channels of the ligand-gated nicotinic acetylcholine receptor superfamily are the most prevalent biomarkers. The autoimmune neurologic disorders associating most commonly with thymoma are myasthenia gravis (MG), peripheral nerve hyperexcitability (neuromyotonia and Morvan syndrome), dysautonomia, and encephalitis. Patients presenting with these neurologic disorders should be screened for thymoma at diagnosis. Although they can cause profound disability, they usually respond to immunotherapy and treatment of the thymoma. Worsening of the neurologic disorder following surgical removal of a thymoma may herald tumor recurrence. Prompt recognition of paraneoplastic neurologic disorders is critical for patient management. A multidisciplinary approach is required for optimal management of neurologic autoimmunity associated with thymoma.

The Role of Thymoma and Thymic Hyperplasia as Prognostic Risk Factors for Secondary Generalisation in Adults with Ocular Myasthenia Gravis: A Systematic Narrative Review

Purpose

The conversion of ocular myasthenia gravis (OMG) to generalised myasthenia gravis (GMG) is reported to differ depending on the presence of generalisation risk factors (Mazzoli et al. 2018). Thymic pathology has been recognised as a potential risk factor for generalisation in the literature (Teo et al. 2017). Thymoma and thymic hyperplasia have yet to be examined as a risk factor for generalisation of OMG independently of other risk factors in the literature. Thus, the purpose of this review is to examine the literature to identify whether thymoma and thymic hyperplasia do increase the risk of OMG progressing to GMG.

Methods

A literature search was carried out which employed a systematic approach. The search was undertaken using the following academic libraries: MEDLINE, Embase and Starplus. The search was limited to publications between the years 2001 to 2021. The search yielded 82 studies, which after the screening of titles and abstracts, left 62 studies for further analysis against the inclusion and exclusion criteria.

Results

The review found thymoma to be associated with an increased risk of GMG development. However, there was a scarce amount of literature which investigated thymic hyperplasia. Therefore, a firm conclusion could not be made with regards to thymic hyperplasia and the risk of GMG development.

Conclusions

This review provides evidence for the consideration of thymectomy early after thymomatous OMG diagnosis to prevent GMG conversion. As the review did not collect enough evidence to support the influence of thymic hyperplasia on OMG conversion, further research is required.

Significance of Acetylcholine Receptor Antibody Titers in Acetylcholine Receptor Antibody-Positive Ocular Myasthenia Gravis: Generalization and Presence of Thyroid Autoimmune Antibodies and Thymoma

Objective

To evaluate the association in acetylcholine receptor (AChR) antibody-positive ocular myasthenia gravis (OMG) subjects between AChR antibody titers and conversion to generalized myasthenia gravis (GMG), the presence of thyroid autoimmune antibodies, and the presence of thymoma.

Subjects and Methods

A total of 118 subjects with AChR antibody-positive OMG were included. Demographic data, clinical characteristics, serology tests, presence of thymoma, treatment, and conversion to GMG were retrospectively reviewed. The presence of thyroid autoimmune antibodies was defined as the presence of at least one of the following: (1) thyroid peroxidase antibody; (2) thyroglobulin antibody; (3) thyroid-stimulating hormone receptor antibody. Univariate and multivariate logistic regression analyses were used as methods of evaluating association.

Results

AChR antibody titers were determined in all subjects with a median of 3.33 (0.46-141.09) nmol/L. The median follow-up period was 14.5 (3-113) months. At the final follow-up time-point, 99 subjects (83.90%) remained with a diagnosis of pure OMG, while 19 subjects (16.10%) had converted to GMG. An AChR antibody titer ≥8.11 nmol/L was associated with the conversion to GMG (odds ratio (OR) 3.66, 95% CI: 1.19-11.26; p = 0.023). Of the 79 subjects with available thyroid autoimmune antibodies data, 26 subjects (32.91%) displayed the presence of thyroid autoimmune antibodies. An AChR antibody titer ≥2.81 nmol/L was associated with the presence of thyroid autoimmune antibodies (OR 6.16, 95% CI: 1.79-21.22; p = 0.004). Finally, of the 106 subjects with available thoracic computed tomography (CT) data, only 9 subjects (8.49%) demonstrated the presence of thymoma. An AChR antibody titer ≥15.12 nmol/L was associated with the presence of thymoma (OR 4.97, 95% CI: 1.10-22.48; p = 0.037).

Conclusion

AChR antibody titers should be considered in AChR antibody-positive OMG patients. Those with AChR antibody titers ≥8.11 nmol/L, who are at a greater risk of conversion to GMG, should be closely monitored and encouraged to be aware of early clinical signs of life-threatening GMG. In addition, serum thyroid autoimmune antibodies and thoracic CT screening for thymoma should be performed in AChR antibody-positive OMG patients, particularly in those with AChR antibody titers ≥2.81 nmol/L and ≥15.12 nmol/L, respectively.

Identification of Potential Serum Protein Biomarkers in Thymoma with Myasthenia Gravis After Docetaxel Treatment

INTRODUCTION

Myasthenia gravis (MG) is a devastating acquired autoimmune disease that can seriously affect the patient's quality of life. It is also a common complication of thymoma. Previous studies have shown that docetaxel alleviates myasthenic symptoms in thymoma with MG (TMG). However, little is known about the protein expression profiles and biomarkers for efficacy after docetaxel treatment.

METHODS

We recruited 9 healthy controls and 30 patients with TMG for the serum proteomics study with data-independent acquisition (DIA) technology. We further recruited additional 30 patients for the key protein validation by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We identified 43 proteins by trend analysis and analyzed the interaction between these proteins and MG pathogenic proteins from the DisGNET database and the correlation analysis with clinical data of patients with TMG. Among these, KRAS and SELP were screened out and validated. KRAS and SELP increased in patients with TMG and decreased significantly after docetaxel treatment.

CONCLUSIONS

Our study revealed that the serum proteins were differentially expressed after docetaxel treatment, suggesting their important role in patients with TMG, as well as the critical role of KRAS and SELP as biomarkers in evaluating the efficacy of docetaxel treatment.

Comparison of Short-Term Post-Thymectomy Outcomes by Time-Weighted Dosages of Drug Requirements between Thymoma and Non-Thymoma Myasthenia Gravis Patients

(1) Background: Early thymectomy is suggested in all clinically indicated myasthenia gravis (MG) patients. However, short-term clinical response after thymectomy in MG patients has been limitedly described in the literature. This study aimed to compare the 5-year post-thymectomy outcomes between thymoma (Th) and non-thymoma (non-Th) MG patients. (2) Methods: MG patients aged ≥18 years who underwent transsternal thymectomy and had tissue histopathology reports in Songklanagarind Hospital between 2002 and 2020 were enrolled in a retrospective review. The differences in the baseline demographics and clinical characteristics between ThMG and non-Th MG patients were studied. We compared the time-weighted averages (TWAs) of daily required dosages of pyridostigmine, prednisolone or azathioprine to efficiently maintain daily living activities and earnings between the MG patient groups during 5 consecutive years following thymectomy. Post-thymectomy clinical status, exacerbations or crises were followed. Descriptive statistics were used for analysis with statistical significance set at p < 0.05. (3) Results: ThMG patients had significantly older ages of onset and shorter times from the MG diagnosis to thymectomy. Male gender was the only significant factor associated with ThMG. TWAs of the daily MG treatment drug dosages required showed no differences between the groups. Additionally, the rates of exacerbations and crises were not different, but decremental trends were shown in both groups after the thymectomies. (4) Conclusions: The daily dosage requirements of MG treatment drugs were not different. There was a trend of decreasing adverse event rates despite no statistically significant differences during the first 5 years after thymectomy in ThMG and non-ThMG patients.

Risk factors for postoperative myasthenia gravis in patients with thymoma without myasthenia gravis: A systematic review and meta-analysis

INTRODUCTION

According to the principle, thymomas combined with myasthenia gravis (MG) require surgical treatment. However, patients with non-MG thymoma rarely develop MG and early- or late-onset MG after surgery is called postoperative MG (PMG). Our study used a meta-analysis to examine the incidence of PMG and risk factors.

METHODS

Relevant studies were searched for in the PubMed, EMBASE, Web of Science, CNKI,and Wanfang databases. Investigations that directly or indirectly analyzed the risk factors for PMG development in patients with non-MG thymoma were included in this study. Furthermore, risk ratios (RR) with 95% confidence intervals (CI) were pooled using meta-analysis, and fixed-effects or random-effects models were used depending on the heterogeneity of the included studies.

RESULTS

Thirteen cohorts containing 2,448 patients that met the inclusion criteria were included. Metaanalysis revealed that the incidence of PMG in preoperative patients with non-MG thymoma was 8%. Preoperative seropositive acetylcholine receptor antibody (AChR-Ab) (RR = 5.53, 95% CI 2.36 - 12.96, P<0.001), open thymectomy (RR =1.84, 95% CI 1.39 - 2.43, P<0.001), non-R0 resection (RR = 1.87, 95% CI 1.36 - 2.54, P<0.001), world health organization (WHO) type B (RR =1.80, 95% CI 1.07 - 3.04, P= 0.028), and postoperative inflammation (RR = 1.63, 95% CI 1.26 - 2.12, P<0.001) were the risk factors for PMG in patients with thymoma. Masaoka stage (P = 0.151) and sex (P = 0.777) were not significantly associated with PMG.

DISCUSSION

Patients with thymoma but without MG had a high probability of developing PMG. Although the incidence of PMG was very low, thymectomy could not completely prevent the occurrence of MG. Preoperative seropositive AChR-Ab level, open thymectomy, non-R0 resection, WHO type B, and postoperative inflammation were risk factors for PMG.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022360002.

Concurrent de novo Thymoma-associated Paraneoplastic Type 1 Autoimmune Hepatitis and Pure Red Cell Aplasia after Thymectomy: A Case Report and Literature Review

The precise manipulation of immune tolerance is the holy grail of immunotherapies for both autoimmunity and cancer immunity. Thymomas are well known to be associated with autoimmune diseases. The exact mechanism by which autoreactivity is induced after thymectomy remains to be elucidated. We herein present the case of a 50-year-old lady with concurrent de novo type 1 autoimmune hepatitis (AIH) and pure red cell aplasia (PRCA), 1 month after undergoing a successful total thymectomy for combined squamous cell carcinoma and thymoma (Masaoka stage II). Corticosteroids yielded short-term effects for both AIH and PRCA. Literature on thymoma-associated AIH, an extremely rare immune-related comorbidity, was also reviewed.

Epigenetics of Thymic Epithelial Tumors

Thymic epithelial tumors (TETs) arise from the epithelial cells of the thymus and consist in the 1% of all adult malignancies, despite the fact that they are the most common lesions of the anterior mediastinum. TETs can be divided mainly into thymomas, thymic carcinomas, and the rarest ad aggressive neuroendocrine forms. Despite the surgical resection is quite resolving, the diagnosis of TETs is complicated by the absence of symptoms and the clinical presentation aggravated by several paraneoplastic disorders, including myasthenia gravis. Thus, the heterogeneity of TETs prompts the search for molecular biomarkers that could be helpful for tumor characterization and clinical outcomes prediction. With these aims, several researchers investigated the epigenetic profiles of TETs. In this manuscript, we narratively review the works investigating the deregulation of epigenetic mechanisms in TETs, highlighting the need for further studies combining genetic, epigenetic, and expression data to better characterize the different molecular subtypes and identify, for each of them, the most relevant epigenetic biomarkers of clinical utility.

Is there a Need to Change the Basic Principles of Histology? Educational, Functional and Embryological Perspective

Although it is not an easy task to classify cells into different types, or in turn cell types into tissue types, a clear, understandable, didactically and clinically relevant tissue classification is indispensable for undergraduate medical education, expert discussions in biomedical research as well as for clinical practice. From the earliest discovery of the light microscope on, tissue classification has been a dynamic process. Historically, it was not a rare occurrence that different textbooks offered different tissue classifications. Nowadays, classifications have almost become uniform – the most common is the histological classification into four basic tissue types (epithelial, connective, muscle, nervous), which is recognized by the majority of modern histology and pathology textbooks. The reason is that, with some exceptions, this classification seems to be the most relevant not only for educational purposes but also from an embryological perspective and clinical-histopathological practice. Recently, attempts have been made to abandon this established classification and replace it with a new one. Any new classification, which would improve the presently used is welcomed. However, if the proposed innovation does not satisfy the needs of modern education and clinical practice, it should be handled with great caution or reconsidered.

Unique correlation between GTF2I mutation and spindle cell morphology in thymomas (type A and AB thymomas)

AIM

Recent study has revealed frequent GTF2I mutation in thymomas, with the frequency being highest in types A and AB, followed by B1, B2, B3 and thymic carcinoma. This has led to the conclusion that GTF2I mutation correlates with more indolent histology subtype and better prognosis. In our study, the GTF2I mutation was tested in thymic epithelial tumours to investigate the relation between the mutation status and histology subtype.

METHODS

The GTF2I mutation was tested in 111 thymic epithelial tumours by Sanger sequencing. Correlations between GTF2I mutation status and clinicopathological parameters were evaluated.

RESULTS

There were 16 cases of type A, including atypical type, 37 type AB, 13 B1, 23 B2, 9 B3, 6 micronodular type, 2 metaplastic type and 5 thymic carcinomas. GTF2I mutation was seen in 78.6% of type A and 83.9% of type AB, while it was not expressed in type B, metaplastic type or thymic carcinoma (p<0.001). 75% of micronodular type also showed the mutation. Both thymoma histotype and stage were significantly associated with GTF2I mutation by univariate analysis. The presence of GTF2I mutation showed a trend towards a favourable prognosis, but this is likely due to their strong association with more indolent histologic subtypes (types A and AB).

CONCLUSIONS

GTF2I mutation appears unique in type A and AB thymomas, including those with atypical features and micronodular type, all of which share spindle cell morphology, indicating they represent a group biologically distinct from type B thymomas.

An unusual presentation of thymoma: dysgeusia, ulcerative colitis, keratoconjunctivitis sicca, autoimmune retinopathy and myasthenia gravis

A 41-year-old female presented with dysgeusia, dry eyes, nyctalopia with progressive visual field constriction (due to autoimmune retinopathy) and gastrointestinal symptoms (due to ulcerative colitis). She was subsequently admitted to intensive care with a myasthenic crisis, and CT of the thorax demonstrated a thymoma.Following thymectomy and adjuvant radiotherapy, she has remained in complete remission from her ulcerative colitis and myasthenia gravis, her retinopathy has stabilised and there has been no thymoma recurrence over a 10-year postoperative period. There was a brief relapse of her dysgeusia (causing weight loss) and dry eye symptoms 3 years after her surgery, which resolved 8 months later. While the association of thymomas with paraneoplastic syndromes (PNS) is well established, it is unusual to present with multiple PNS, and some of these have only been documented in sparse case reports to date. Thymectomy played a crucial role in improvement and stabilisation of her PNS.

Pure Red Cell Aplasia and Other Haematological Diseases Associated With Thymoma: A Case Series and Systematic Review

Background: Thymoma-associated haematological diseases (HDs), such as pure red cell aplasia (PRCA) and Good's syndrome, are extremely rare, and due to the paucity of large-scale studies, the characteristics, remission after thymectomy, and long-term evaluation remain undetermined.

Methods: We retrospectively assessed patients with thymoma and associated HDs from Jan 2005 to Dec 2020. All patients received thymectomy and/or additional treatments for HDs. A comparison with thymoma-associated myasthenic gravis (MG), and a systematic review from PubMed/MEDLINE and Embase were conducted.

Results: In the median follow-up of 56 months, 130 patients were enrolled. Patients with thymoma-associated MG (n = 46) and HDs [n = 8; PRCA (n = 5), PRCA and Good's syndrome (n = 2) and autoimmune haemolytic anaemia (n = 1)] were evaluated. Patients with MG had a significantly higher remission rate after thymectomy (50 vs. 17%; p = 0.0378) as compared to those with other autoimmune diseases. Two of seven patients with PRCA experienced remission with thymectomy alone, and an additional two patients achieved remission with thymectomy plus immunosuppressive therapy (IST). In the systematic review, 60 studies (case reports, n = 46; case series including the present study, n = 14) were evaluated. Forty-four percent of patients were diagnosed with PRCA after thymoma, and 61% achieved remission with thymectomy plus IST; however, Good's syndrome was unaffected.

Conclusions: Our study indicates that patients with thymoma-associated autoimmune diseases other than MG have a lower remission rate than those with MG. Remission of thymoma-associated PRCA can be achieved by thymectomy and IST. This study provides insight into extremely rare but puzzling autoimmune manifestations.

The efficacy and safety of immunotherapy in thymic epithelial tumors: more effective, more risky: a systematic review

Background

Thymic epithelial tumors (TETs) are rare malignant neoplasms originating from thymic epithelial cells. The current treatment for localized TETs is surgical removal. However, 20-30% of thymomas and 70-80% of thymic carcinomas are unresectable, recurrent, or metastatic at the time of detection. The standard therapy for these patients is chemotherapy, but the effect is limited. With a deeper understanding of tumor immunity, immunotherapy for various cancers has rapidly developed. Antibodies against cytotoxic T-lymphocyte antigen-4, programmed death-1, and programmed death-ligand 1 have been approved for the treatment of many solid tumors. Compared with traditional treatments, these immune checkpoint inhibitors (ICIs) have better efficacy and lower toxicity. Recently, ICIs have been used more enthusiastically in the treatment of TETs. However, due to the unique biological characteristics of the thymus, immunotherapy usually causes severe immune-related adverse events (irAEs). Most previous studies on immunotherapy in TETs had small sample sizes and reported diverse conclusions.

Methods

We collected relevant studies in PubMed during the last five years and analyzed the available data to discuss the efficacy and safety of ICIs in TETs.

Results

According to 14 previous studies in the past five years, all TETs showed expression of programmed death-ligand 1, while thymic carcinomas showed 100% expression. The best median progression-free survival (mPFS) among the five studies was 6.5 months, and the best median overall survival (mOS) was 24.9 months. In addition, the most common irAEs were myasthenic symptoms, liver enzyme elevation, and elevated creatine phosphokinase levels.

Conclusions

ICIs can be used in TET treatment, especially for thymic carcinomas, in the absence of standard second-line treatment. However, more attention should be paid to irAEs.

STAT3 activation in thymic epithelial tumors: correlation with cyclin D1, JAK3, and clinical behavior

OBJECTIVES

Thymic epithelial tumors are the most common adult mediastinal tumors; however, their growth mechanism remains relatively unknown. Among the JAK/STAT pathway-related proteins, which control various intracellular events, STAT3 is deeply involved in cell proliferation. Constitutive activation of STAT3 and the resulting overexpression of cyclin D1 have been confirmed in various tumors, but have not been thoroughly investigated in thymic epithelial tumors. In this study, we immunohistochemically examined STAT3 activation, cyclin D1 expression, and JAK3 activation in thymic epithelial tumors and statistically analyzed their correlation with clinicopathological features.

METHODS

Formalin-fixed paraffin-embedded specimens of 94 thymic epithelial tumors surgically resected at Kyorin University Hospital between 2005 and 2018 were included in this study. pSTAT3, cyclin D1, and pJAK3 were immunohistochemically examined, and the correlation with histology, Masaoka stage, and survival time was statistically analyzed.

RESULTS

Cyclin D1 was found to be significantly overexpressed in the STAT3-activated group. This phenomenon was associated with histology and Masaoka stage. JAK3 was also activated in thymic epithelial tumors; however, JAK3 and STAT3 activation were not always correlated. Using survival time analysis, the STAT3-activated group, cyclin D1-expressed group, and JAK3-activated group had significantly lower progression-free survival times than those for both the non-activated and non-expressed groups.

CONCLUSIONS

STAT3 activation may promote cyclin D1 overexpression in thymic epithelial tumors, and intracellular signaling pathways other than JAK3 may be involved in STAT3 activation. STAT3 activation, cyclin D1 overexpression, and JAK3 activation are biomarker candidates that indicate clinically poor prognosis.

Clinical features and prognostic impact of coexisting autoimmune disease other than myasthenia gravis in resected thymomas: analysis of a Japanese multi-institutional retrospective database

OBJECTIVES

The purpose of this study was to clarify the prevalence, clinical features and survival of patients with thymoma and non-myasthenia gravis autoimmune disease (NMAD) using a nationwide cohort.

METHODS

The Japanese Association for Research on the Thymus nationwide database, which includes data from 32 institutions, was examined to clarify the prevalence and characteristics of NMAD associated with thymomas and elucidate the prognostic impact of NMAD for thymoma patients.

RESULTS

Among the 2423 patients with thymomas who were surgically treated between 1991 and 2010, 114 (4.7%) were identified with NMAD. The most frequently observed NMAD was pure red cell aplasia (PRCA) in 44 (1.8%), followed by hypogammaglobulinaemia (0.5%) and rheumatic arthritis (0.5%). Twenty-eight percent of patients with NMAD had concomitant myasthenia gravis. The presence of NMAD was not an independent prognostic factor for overall survival (OS) irrespective of the type of NMAD [PRCA+: hazard ratio (HR) 1.99, 95% confidence interval 0.74-4.47; PRCA- NMAD: HR 1.28, 0.30-3.56]; however, there were more cases with advanced age and disease of the thymoma amongst PRCA+ patients and these showed a worse OS than patients with PRCA- NMAD (P < 0.001), who had an OS similar to those without NMAD (P = 0.489). The 10-year OS rates in PRCA+, PRCA- NMAD and NMAD- groups were 45.5%, 97.4% and 89.5%, respectively. The main causes of death in PRCA+ patients were the progression of thymoma and other diseases including pneumonia.

CONCLUSIONS

Although the presence of NMAD itself did not significantly affect survival after surgery for thymoma, the type of NMAD was associated with different clinical features and prognosis. The NMAD+ thymomas should be separately categorized according to the presence or absence of PRCA.

Thymoma pathology and myasthenia gravis outcomes

INTRODUCTION

There is limited evidence regarding the impact of World Health Organization (WHO) subtype of thymoma on post-thymectomy outcome of thymoma-associated myasthenia gravis (TAMG). The objective was to determine if the pathological subtypes of thymoma were associated with post-thymectomy outcomes of myasthenia gravis (MG), in patients with TAMG.

METHODS

We performed a retrospective study of consecutive patients with TAMG who attended the neuromuscular clinic between January 2018 and December 2019 with a minimum follow-up of 1 y after thymectomy. Outcome measures were MG Impairment Index (MGII), single-simple question (SSQ), Myasthenia Gravis Foundation of America post-intervention status (MGFA PIS) and non-responder MG status at last assessment.

RESULTS

Ninety-five patients were included; mean age at onset was 48.1 ± 12.1 y; 54(56.8%) were females. Thirteen patients developed MG post-thymectomy. The most common thymoma was WHO type B2 in 39 (41.1%). Most patients (40, 42.1%) had Masaoka stage II thymoma. There was no association of thymoma subtypes or Masaoka stage of disease with age, gender, MG phenotype, serology, post-thymectomy onset, interval from onset to thymectomy, MGII, SSQ, MGFA PIS, or non-responder status. Associations were found between positive serology and lower MGII (11.1 ± 14.2 vs 23 ± 12.9, P = .050), thymic follicular hyperplasia (TFH) and higher SSQ (89.3 ± 11.7 vs 80.1 ± 20.2, P-.043), and lack of recurrence and higher SSQ (84.1 ± 18 vs 72.5 ± 20, P = .037).

DISCUSSION

The WHO pathological subtype of thymoma did not correlate with MG outcomes. However, positive acetylcholine antibody serology, presence of TFH, and non-recurrence of thymoma predict a favorable outcome.

Risk factors for developing post-thymectomy myasthenia gravis in patients with thymoma

BACKGROUND

Thymectomy is required for the treatment of thymoma-associated myasthenia gravis (MG). However, MG may develop only after thymectomy, a condition known as post-thymectomy MG. This study aimed to investigate the risk factors for post-thymectomy MG in patients with thymoma.

METHODS

We retrospectively identified 235 patients with thymoma who underwent thymectomy at a single hospital from January 2008 to December 2017: 44 with preoperatively diagnosed MG were excluded, leaving 191 patients in the final analysis. Univariable survival analyses using Cox proportional hazards regression model and Kaplan-Meier estimate were conducted to identify risk factors for post-thymectomy MG.

RESULTS

Post-thymectomy MG developed in 4.2% (8/191) of the patients with thymoma between 18 days and 108 mo after surgery. Hazard ratios (HRs) of pre- and postoperative anti-acetylcholine receptor antibody (AChR-Ab) titers were 2.267 (P = .002) and 1.506 (P < .001), respectively. Patients with extended thymectomy had a low chance of post-thymectomy MG (HR 0.035, P = .007). Larger thymoma (HR, 1.359; P = .005) and type A or AB thymoma according to World Health Organization histological classification (HR, 11.92; P = .021) were associated with higher chances of post-thymectomy MG. Within the subgroup of preoperatively AChR-Ab seropositive patients, post-thymectomy MG developed in 22.2% (6/27).

CONCLUSIONS

Pre- and postoperative AChR-Ab levels should be measured in patients with thymoma. A large thymoma and partial thymectomy appear to be associated with a higher probability of post-thymectomy MG.

Immunodeficiency and thymoma in Good syndrome: Two sides of the same coin

Good Syndrome is a rare clinical entity first described as the conjunction of thymoma and hypogammaglobulinemia, and more recently depicted as a complex disease integrating a medical history of thymoma with humoral immunodeficiency (more accurately stated: hypogammaglobulinemia) with or without cellular immunodeficiency, recurrent infections, autoimmunity, paraneoplastic syndromes and diverse aberrations in the immunological profile. This condition has an ominous prognosis with a high mortality rate secondary to recalcitrant infectious diseases. Understanding the possible discordances in clinical presentation and the temporal relationship between manifestations and immunological alterations is key to prevent misdiagnosis and complications. To this end, here we provide two illustrative patients with Good Syndrome that share common clinical manifestations and yet show unique and opposed immunological profiles, thereby highlighting the pivotal interest of a comprehensive immunological profiling in these patients. We conducted a thorough review of existing literature on the elusive molecular mechanisms underlying the syndrome and provide a clinical assessment algorithm to facilitate the management of these challenging patients.

Invasive Thymoma with Right Upper Lobe Endobronchial Lesion and Autoimmune Enteropathy

Thymomas are slow-growing neoplasia arising from the epithelial cells of the thymus that usually present with respiratory symptoms, superior vena cava syndrome, or parathymic syndromes. Approximately 30% of thymomas develop myasthenia gravis. An additional 5% of patients with thymomas have other systemic syndromes, including rheumatoid arthritis, thyroiditis, red cell aplasia, systemic lupus erythematosus, and Cushing syndrome. Rarely, patients can present with diarrhea due to thymoma-associated autoimmune gastrointestinal pathologies that include Good syndrome (acquired hypogammaglobulinemia), thymoma- associated multiorgan autoimmunity, and autoimmune enteropathy. We present an uncommon and interesting case of an invasive metastatic thymoma with right upper lobe endobronchial lesion and autoimmune enteropathy in a 27-year-old female. The novelty of this case lay in the findings of extensive metastatic thymoma with right upper lobe endobronchial disease and autoimmune diarrhea.

Coexistence of Pure Red Cell Aplasia and Autoimmune Haemolytic Anaemia Associated with Thymoma

Thymoma is an uncommon neoplasia derived from the epithelial cells of the thymus, which leads to immune dysregulation and is associated with a series of autoimmune diseases. However, the concurrence of these disease entities is rare, and the exact mechanisms of these diseases are still unclear. We have admitted several cases who were diagnosed with thymoma, autoimmune haemolytic anaemia, and pure red cell aplasia. These cases were the first to report the concurrence of these three disorders. After thymectomy, anaemia improved, haemolytic cells decreased, and haemoglobin was normalized.

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.

Risk Factors for the Exacerbation of Myasthenic Symptoms After Surgical Therapy for Myasthenia Gravis and Thymoma

Extended thymectomy is employed for patients with myasthenia gravis (MG) and/or thymoma with elevated serum antiacetylcholine receptor antibody (AchR) titers. However, MG symptoms occasionally worsen in post-thymectomy patients. We explored the risk factors for exacerbation of MG symptoms after surgical therapy for patients with MG and/or thymoma with an elevated AchR titer. We retrospectively analyzed 90 patients suffering from MG and/or thymoma with an elevated AchR titer who underwent thymectomy in our institute. Patients were classified into Improved, Unchanged, and Exacerbated groups by assessing their postoperative myasthenic symptoms, amount of medication, and incidence of myasthenic crisis. Risk factors for postoperative exacerbation of myasthenic symptoms were assessed by comparing the Exacerbated with the Improved and Unchanged groups. Of the 90 patients, 29 were classified into the Improved group, 47 into the Unchanged group, and 14 into the Exacerbated group. The presence of thymoma and Masaoka stage were significantly different between the Exacerbated and Improved/Unchanged groups. Although preoperative AchR titers did not significantly differ among the groups, the perioperative AchR titers in the Exacerbated group were significantly higher than those in the other groups (P = 0.003). A multiple logistic regression analysis with stepwise forward selection showed that advanced-stage thymoma was a risk factor for postoperative exacerbation of myasthenic symptoms (P = 0.007). Patients with advanced-stage thymoma have a relative risk for exacerbation of myasthenic symptoms after surgical therapy.

The Cancer Genome Atlas dataset-based analysis of aberrantly expressed genes by GeneAnalytics in thymoma associated myasthenia gravis: focusing on T cells

Background

Myasthenia gravis (MG) is a group of autoimmune disease which could be accompanied by thymoma. Many differences have been observed between thymoma-associated MG (TAMG) and non-MG thymoma (NMG). However, the molecular difference between them remained unknown. This study aimed to explore the differentially expressed genes (DEGs) between the two categories and to elucidate the possible pathogenesis of TAMG further.

Methods

DEGs were calculated using the RNA-Sequencing data from 11 TAMG and 10 NMG in The Cancer Genome Atlas (TCGA) database. GeneAnalytics was performed to characterize the associations between DEGs and tissues and cells, diseases, gene ontology (GO) terms, pathways, phenotypes, and drug/compounds, respectively. Genes related to T cells were sorted out using LifeMapDiscovery Cells and Tissues Database. Genes directly related to the phenotype of autoimmune diseases that were identified by VarElect were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

Results

The expression level of 169 genes showed a significant difference between the two groups, with 94 up-regulated and 75 down-regulated. Overexpression of six genes (ATM, SFTPB, ANKRD55, BTLA, CCR7, TNFRSF25), which are expressed in T cells and directly related to autoimmune disease through VarElect, was identified. The overexpression of soluble BTLA (sBTLA) (P=0.027), CCR7 (P=0.0018), TNFRSF25 (P=0.0013) and ANKRD55 (P=0.0026) was validated by RT-qPCR in thymoma tissues from our center.

Conclusions

Overexpression of sBTLA, CCR7, TNFRSF25 and ANKRD55 was identified and validated by RT-qPCR, which could partly explain the underlying pathogenesis in TAMG.

Thymic epithelial tumor complicated by immunological abnormalities: results from a single-center retrospective study in China

Background

To describe the clinical manifestations, immunological features, treatments, and outcomes of patients with thymic epithelial tumor (TET) complicated by immunological abnormalities, and to improve knowledge on immunological abnormalities in this rare disease.

Methods

Patients with pathologically confirmed TET at Beijing Chaoyang Hospital between January 2013 and May 2018 were included in this study, and clinical data were analyzed retrospectively. Immunological abnormalities were classified into two groups as follows: Good syndrome (GS) and autoimmune disease (AD).

Results

Fifty-nine TET patients were enrolled; twenty-two patients (37.3%) had immune dysfunction. There were no gender, age, or histological type differences between groups with or without immunological abnormalities. Six patients had GS, of whom four patients were diagnosed after thymectomy. Recurrent respiratory infections, particularly opportunistic infections, were the most common manifestation. Three GS patients developed a second cancer (50%; P=0.011). Anti-infective therapy and immunoglobulin supplements effectively treated GS. Seventeen patients developed ADs, including myasthenia gravis (MG) (n=13), Hashimoto's thyroiditis (n=4), Sjogren's syndrome (n=1), rheumatoid arthritis (n=1), pemphigus (n=1), and Evans syndrome (n=1). One patient developed both MG and GS and 4 patients presented with two ADs. Three AD cases occurred after thymectomy. Pemphigus and 80% (8/10) of MG cases were resolved following thymectomy.

Conclusions

There is a strong association between immunological abnormalities and TET, which may present at any time point during the disease, even after thymectomy. In addition to infection, GS patients are more likely to develop a second cancer. Thymectomy may produce favorable outcomes for MG in this study, while surgery does not improve immunodeficiency in GS patients.

Genome‑wide DNA methylation profile of thymomas and potential epigenetic regulation of thymoma subtypes

The aim of the present study was to examine the whole-genome DNA methylation status of thymomas and identify differences in thymoma DNA methylation profiles. DNA methylation profiles of tissues (n=12) were studied using the Infinium MethylationEPIC BeadChip microarray (850K) and analyzed in relation to gene expression data. Functional annotation analysis of DNA methylation between the different groups was performed using the online tool GeneCodis3. In order to assess the diagnostic value of candidate DNA methylation markers, receiver operation characteristic (ROC) analysis was performed using the pROC package. A total of 10,014 CpGs were found to be differentially methylated (Δβ>0.2) between two thymoma types (type A and B). Combination analysis showed that 36 genes had differentially methylated CpG sites in their promoter region. ‘Pathways in cancer’, ‘focal adhesion’ and ‘regulation of actin cytoskeleton’ were the most enriched KEGG pathways of differentially methylated genes between tumor and controls. Among the 29 genes that were hypomethylated with a high expression, zinc finger protein 396 and Fraser extracellular matrix complex subunit 1 had the largest area under the curve. The present results may provide useful insights into the tumorigenesis of thymomas and a strong basis for future research on the molecular subtyping of epigenetic regulation in thymomas.

Changing pattern of secondary cancers among patients with malignant thymoma in the USA

BACKGROUND

The risk of developing secondary cancers (SCs) among patients with malignant thymoma in the US has not been estimated in the more recent time period. Methods: We extracted demographic and treatment data from the SEER database to estimate the standardized incidence ratios (SIRs). Results: Of 1570 patients with thymoma 211 (13.4%) had SCs. The overall risk of developing SCs was higher among patients with thymoma (SIR: 1.54, 95% CI: 1.34-1.76). The SIRs for cancers of lung, esophagus, sigmoid colon, soft tissue and heart, kidney, NHL and leukemia was significantly higher as compared to the general US population. Conclusions: Patients with thymoma are at modestly elevated risk of developing SCs as compared to the general US population. Although the overall risk has not changed after 14 additional years of follow up, the distribution of SCs has significantly broadened, with increased diversity across type and anatomic location of SCs.

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.

Epstein-Barr virus in tumor-infiltrating B cells of myasthenia gravis thymoma: an innocent bystander or an autoimmunity mediator?

The thymus plays a key role in myasthenia gravis (MG), a B cell-mediated autoimmune disorder affecting neuromuscular junction. Most MG patients have thymic abnormalities, including hyperplasia and thymoma, a neoplasm of thymic epithelial cells. Epstein-Barr virus (EBV) is associated with autoimmune diseases and tumors. Recently, we showed EBV persistence and reactivation in hyperplastic MG thymuses, suggesting that EBV might contribute to intra-thymic B cell dysregulation in MG patients. Here, we investigated EBV involvement in thymoma-associated MG, by searching for EBV markers in MG (n=26) and non-MG (n=14) thymomas. EBV DNA and EBV-encoded small nuclear RNA (EBER) 1 transcript were detected in 14/26 (53.8%) and 22/26 (84.6%) MG thymomas, and only in 3 of 14 (21.4%) non-MG thymomas. Latent EBNA2 and late gp350/220 lytic transcripts were undetectable in all, but one, thymomas, and early lytic BZLF1 transcript was absent in all samples, suggesting that early infection events and EBV reactivation were very rare in thymomas. EBER1 and 2-positive cells were detected in MG, but not in non-MG, thymomas, as well as cells expressing EBV latency proteins (EBNA1, LMP1, LMP2A), that were mainly of B cell phenotype, indicating EBV association with MG rather than with thymoma. Toll-like receptor (TLR) 3 transcriptional levels were higher in MG than non-MG thymomas and positively correlated with EBER1 levels, suggesting a role for EBERs in TLR3 activation. Our findings show that EBV is commonly present in thymoma-infiltrating B cells of myasthenic patients, indicating a contribution of EBV to B cell-mediated autoreactivity in MG associated with thymic tumor.

Significance of B10 cell in patients with thymoma complicated with myasthenia gravis

A subset of regulatory B cells in humans has been identified as B10 cell which has the function of secreting interleukin-10. We evaluated the significance of B10 cell in patients with thymoma complicated with myasthenia gravis. In this study, 156 patients diagnosed with thymoma were enrolled, FCM was used to detected the percentage of Breg/CD19⁺B cells and CD19⁺B cells/PBMC, ELISA to evaluate the serum concentration of the relevant immunological markers; purified CD19⁺B cells in tissues by MACS; gene and protein expressions of CD19 and IL-10 by Real-time PCR and Western-Blot; double immunofluorescence staining to detect the distribution of CD19 and IL-10 in thymus tissues. Thymoma patients without MG mainly display the types A and AB of thymoma, whereas the thymoma patients with MG mainly display type B (B1, B2 and B3) thymoma; AChR-Ab in Tm + MG group was the highest, with the progress of the disease, the percentage of Breg/CD19⁺B cells increased and B10/CD19⁺B cells decreased (p < 0.05); ROC curve showed that B10 had the greatest significance for the clinical directivity of Tm+MG and cut-off point = 0.55%; in accordance with the Con, Tm and Tm+MG group, the content of CD19⁺IL-10⁺B10 cells increased gradually (p < 0.05); meanwhile, the gene and protein expression levels of CD19 and IL-10 gradually increased in the same way. It is concluded that with the progress of thymoma, the infiltration of Breg in tumour tissue increases; however, as the severity of MG increases, the function of Breg (B10 cell) in peripheral blood decreases and the cut-off point is 0.55%.

Genomic Analysis of Thymic Epithelial Tumors Identifies Novel Subtypes Associated with Distinct Clinical Features

Purpose: To reconcile the heterogeneity of thymic epithelial tumors (TET) and gain deeper understanding of the molecular determinants of TETs, we set out to establish a clinically relevant molecular classification system for these tumors.Experimental Design: Molecular subgrouping of TETs was performed in 120 patients from The Cancer Genome Atlas using a multidimensional approach incorporating analyses of DNA mutations, mRNA expression, and somatic copy number alterations (SCNA), and validated in two independent cohorts.Results: Four distinct molecular subtypes of TETs were identified. The most commonly identified gene mutation was a missense mutation in General Transcription Factor II-I (GTF2I group), which was present in 38% of patients. The next group was identified by unsupervised mRNA clustering of GTF2I wild-type tumors and represented TETs enriched in expression of genes associated with T-cell signaling (TS group; 33%). The remaining two groups were distinguished by their degree of chromosomal stability (CS group; 8%) or instability (CIN group; 21%) based upon SCNA analyses. Disease-free survival and overall survival were favorable in the GTF2I group and unfavorable in the CIN group. These molecular subgroups were associated with TET histology and clinical features including disease-free survival. Finally, we demonstrate high expression of PD1 mRNA and correlation of PD1 and CD8A in the TS subgroup.Conclusions: Molecular subtyping of TETs is associated with disease-free and overall survival. Classification of TETs by a molecular framework could aid in the refinement of staging and in the discovery and development of rational treatment options for patients with TETs. Clin Cancer Res; 23(16); 4855-64. ©2017 AACR.

[Thymoma and autoimmune diseases]

The association between thymoma and autoimmunity is well known. Besides myasthenia gravis, which is found in 15 to 20% of patients with thymoma, other autoimmune diseases have been reported: erythroblastopenia, systemic lupus erythematosus, inflammatory myopathies, thyroid disorders, Isaac's syndrome or Good's syndrome. More anecdotally, Morvan's syndrome, limbic encephalitis, other autoimmune cytopenias, autoimmune hepatitis, and bullous skin diseases (pemphigus, lichen) have been reported. Autoimmune diseases occur most often before thymectomy, but they can be discovered at the time of surgery or later. Two situations require the systematic investigation of a thymoma: the occurrence of myasthenia gravis or autoimmune erythroblastopenia. Nevertheless, the late onset of systemic lupus erythematosus or the association of several autoimmune manifestations should lead to look for a thymoma. Neither the characteristics of the patients nor the pathological data can predict the occurrence of an autoimmune disease after thymectomy. Thus, thymectomy usefulness in the course of the autoimmune disease, except myasthenia gravis, has not been demonstrated. This seems to indicate the preponderant role of self-reactive T lymphocytes distributed in the peripheral immune system prior to surgery. Given the high infectious morbidity in patients with thymoma, immunoglobulin replacement therapy should be considered in patients with hypogammaglobulinemia who receive immunosuppressive therapy, even in the absence of prior infection.

A case of relapsing encephalitis positive for gamma aminobutyric acid (GABA)A receptor antibody associated with Type B3 thymoma

A 87-year-old female presented with subacute progression of cognitive decline. Fluid-attenuated inversion recovery images of brain MRI showed multifocal high-intensity lesions. Thoracic CT image revealed the presence of thymoma, and serum autoantibody screening showed positivity for anti-gamma aminobutyric acid (GABA)_A receptor antibody. Histopathological analysis confirmed type B3 thymoma after thymectomy. The patient received both plasmapheresis and intravenous methylprednisolone therapy, and showed remarkable amelioration of clinical symptoms and MRI abnormal high intensity. However, after 2 month from the clinical recovery, the patient showed recurrence of brain lesions and intravenous methylprednisolone monotherapy was performed. Continuation of oral steroid therapy was required to maintain the quienscent state of inflammation within the central nervous system. Anti-GABA_A receptor antibody is a recently discovered novel autoantibody associated with autoimmue encephalitis. Due to the limited number of literature reported, clinical course and therapeutic response of GABA_A receptor antibody encephalitis remains elusive. Here we reported a rare case of GABA_A receptor antibody encephalitis with type B3 thymoma. Clinical, radiological and therapeutic courses described in our report highlight the importance of immunotherapy for treatment of the disease.

Clinical features of patients with Myasthenia gravis from the Henan province, China

INTRODUCTION

Myasthenia gravis (MG) occurs globally, and many studies have indicated that there are regional differences in epidemiology, biomarkers, and prognosis of MG.

METHODS

A total of 478 patients with MG who visited hospitals in the Henan Province between January 2010 and February 2014 were included. Age, gender, age at onset, serum antibody, thymus pathology, treatment information, and Myasthenia Gravis Foundation of America (MGFA) classification were assessed.

RESULTS

Compared with previous reports from other areas, we found some differences in MG patients from Henan. The proportion of childhood MG in our study was lower than other reports of Oriental patients with MG. There seems to be an association between onset age, muscle involvement, and acetylcholine receptor antibody levels. Thymectomy improved the symptoms in 78.5% of thymectomy-treated patients.

CONCLUSIONS

These differences are likely related to geographical, environmental, and ethnic differences. Understanding these differences will help us to define more specific treatment.

Thymoma and thymic carcinomas

Thymomas (Ts) and thymic carcinomas (TCs) are rare tumours of the mediastinum with an incidence rate of 1.7/million per year in Europe. Histological classification is based on rate of non-malignant-appearing thymic epithelial cells and proportions of lymphocytes (A, AB, B1, B2, B3, and C), while staging system concerns localisation of the involved areas. Surgery is the mainstay of treatment with a 10-year survival of 80%, 78%, 75%, and 42% for stages I, II, III and IV, respectively, with an R0 resection. Radiotherapy has a role in selected cases (stage III patients or R1-2 residual) and platinum-based chemotherapy remains the standard of care for patients with advanced disease. A multimodality approach would be advisable when surgery is not recommended. Since molecular aberrations are poorly understood and few responses are reported, targeted therapies are yet being studied. In this review, we describe key aspects of clinical management for Ts and TCs.

Poly-autoimmunity in patients with myasthenia gravis: A single-center experience

We evaluated the co-occurrence of autoimmune diseases (ADs) in a large population of myasthenia gravis (MG) patients from a single center. Our survey included 984 patients, 904 with anti-acetylcholine receptor antibodies and 80 with anti-muscle specific kinase antibodies. The anti-acetylcholine receptor positive population included patients with early-onset (age at onset ≤ 50 years), late-onset and thymoma-associated disease. Follow-up ranged 2-40 years. Two-hundred and fourteen ADs were diagnosed in 185 patients; 26 of them had two or more ADs in association with MG. Thyroid disorders were the most common and, together with vitiligo and thrombocytopenia, occurred in all disease subsets. Otherwise, there was a broad variability with partial overlap among patient groups. The highest rate of ADs was observed in early-onset patients, while clusters, i.e. 2 or more ADs other than MG in the same individual, were more common among thymoma cases. Thirty-four diseases were diagnosed at the same time, 88 occurred before and 92 after the onset of MG. On multivariate analysis, immunosuppressive treatment was the only independent variable which negatively influenced the risk of developing other ADs in our cohort.

Expression of cell cycle and apoptosis regulators in thymus and thymic epithelial tumors

The human thymus supports the production of self-tolerant T cells with competent and regulatory functions. Various cellular components of the thymic microenvironment such as thymic epithelial cells (TEC) and dendritic cells play essential roles in thymic T cell differentiation. The multiple cellular events occurring during thymic T cell and TEC differentiation involve proteins regulating cell cycle and apoptosis. Dysregulation of the cell cycle and apoptosis networks is involved in the pathogenesis of thymic epithelial tumors (TET) which are divided into two broad categories, thymomas and thymic carcinomas. The present review focuses on the usefulness of the analysis of the expression patterns of major cell cycle and apoptosis regulators in order to gain insight in the histophysiology of thymus and the histopathology, the clinical behavior and the biology of TET.