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

Thymic Imaging Pitfalls and Strategies for Optimized Diagnosis

Thymic imaging is challenging because the imaging appearance of a variety of benign and malignant thymic conditions are similar. CT is the most commonly used modality for mediastinal imaging, while MRI and fluorine 18 fluorodeoxyglucose (FDG) PET/CT are helpful when they are tailored to the correct indication. Each of these imaging modalities has limitations and technical pitfalls that may lead to an incorrect diagnosis and mismanagement. CT may not be sufficient for the characterization of cystic thymic processes and differentiation between thymic hyperplasia and thymic tumors. MRI can be used to overcome these limitations but is subject to other potential pitfalls such as an equivocal decrease in signal intensity at chemical shift imaging, size limitations, unusual signal intensity for cysts, subtraction artifacts, pseudonodularity on T2-weighted MR images, early imaging misinterpretation, flow and spatial resolution issues hampering assessment of local invasion, and the overlap of apparent diffusion coefficients between malignant and benign thymic entities. FDG PET/CT is not routinely indicated due to some overlap in FDG uptake between thymomas and benign thymic processes. However, it is useful for staging and follow-up of aggressive tumors (eg, thymic carcinoma), particularly for detection of occult metastatic disease. Pitfalls in imaging after treatment of thymic malignancies relate to technical challenges such as postthymectomy sternotomy streak metal artifacts, differentiation of postsurgical thymic bed changes from tumor recurrence, or human error with typical "blind spots" for identification of metastatic disease. Understanding these pitfalls enables appropriate selection of imaging modalities, improves diagnostic accuracy, and guides patient treatment. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Prognostic factors in patients with thymoma who underwent surgery

PURPOSE

Thymoma is the most common primary tumor in the anterior mediastinum. The prognostic factors of patients with thymoma still need to be clarified. In this study, we aimed to investigate the prognostic factors of patients with thymoma who received radical resection and establish the nomogram to predict the prognosis of these patients.

MATERIALS AND METHODS

Patients who underwent radical resection for thymoma with complete follow-up data between 2005 and 2021 were enrolled. Their clinicopathological characteristics and treatment methods were retrospectively analyzed. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and compared by the log-rank test. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify the independent prognostic factors. According to the results of the univariate analysis in the Cox regression model, the predictive nomograms were created.

RESULTS

A total of 137 patients with thymoma were enrolled. With a median follow-up of 52 months, the 5-year and 10-year PFS rates were 79.5% and 68.1%, respectively. The 5-year and 10-year OS rates were 88.4% and 73.1%, respectively. Smoking status (P = 0.022) and tumor size (P = 0.039) were identified as independent prognostic factors for PFS. Multivariate analysis showed that a high level of neutrophils (P = 0.040) was independently associated with OS. The nomogram showed that the World Health Organization (WHO) histological classification contributed more to the risk of recurrence than other factors. Neutrophil count was the most important predictor of OS in patients with thymoma.

CONCLUSION

Smoking status and tumor size are risk factors for PFS in patients with thymoma. A high level of neutrophils is an independent prognostic factor for OS. The nomograms developed in this study accurately predict PFS and OS rates at 5 and 10 years in patients with thymoma based on individual characteristics.

Pure Red Cell Aplasia Associated With Thymoma

A 27-year-old male with thymoma presented with recurrent severe anemia which required multiple transfusions. Bone marrow biopsy showed pure red cell aplasia with normal other cell lineages. He was diagnosed with pure red cell aplasia associated with thymoma and treatment with cyclosporine A was begun. After 12 weeks of treatment, his hemoglobin improved to 11.3 g/dL and the patient remained transfusion independent.

Application of Artificial Intelligence in the Diagnosis, Treatment, and Prognostic Evaluation of Mediastinal Malignant Tumors

Artificial intelligence (AI), also known as machine intelligence, is widely utilized in the medical field, promoting medical advances. Malignant tumors are the critical focus of medical research and improvement of clinical diagnosis and treatment. Mediastinal malignancy is an important tumor that attracts increasing attention today due to the difficulties in treatment. Combined with artificial intelligence, challenges from drug discovery to survival improvement are constantly being overcome. This article reviews the progress of the use of AI in the diagnosis, treatment, and prognostic prospects of mediastinal malignant tumors based on current literature findings.

Thymoma-associated autoimmune encephalitis: Analysis of factors determining prognosis

INTRODUCTION

Autoimmune encephalitis (AE) is a heterogeneous group of inflammatory central nervous system disorders caused by a misdirected immune response against self-antigens expressed in the central nervous system. The thymus is a central organ in the immune system and thymic tumors are thought to be possible initiators of many neurological disorders. Recently, there is growing evidence that thymomas are associated with autoimmune encephalitis.

AIMS

Our study initially explored the characteristics of patients with autoimmune encephalitis combined with thymoma.

METHODS

We used patient data from January 1, 2011 to October 1, 2021 from the PubMed, Web of Science, Ovid, and CNKI platforms to analyze overall demographics, frequency of symptoms and associations, and treatment prognosis outcomes.

RESULTS

A total of 68 patients were included. There were 39 female cases (57.4%). The mean age was 50 years (IQR 40-66 years). All had acute and subacute onset. The clinical manifestations were mostly cognitive changes (70.6%), mental disorders (57.4%), and epilepsy (50.0%). The most common neuronal antibody was alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Magnetic resonance imaging (MRI) abnormalities were present in 81.0% of patients, mostly in the hippocampus, temporal lobe, and some in cortical and subcortical areas. Abnormalities in the electroencephalogram (EEG) in 69.8% of patients. Treatment involved immunotherapy and thymoma treatment, with 79.7% of patients improving after treatment. While 20.3% of patients had a poor prognosis. Further, 14.8% of patients relapsed. Mental disorders, autonomic dysfunction, sleep disturbances, anti-Ma2, and thymoma untreated were more frequent in patients with poor prognosis.

CONCLUSION

Thymoma-associated autoimmune encephalitis is a unique disease entity. Long-term follow-up of chest CT findings is recommended for patients with autoimmune encephalitis.

B3 thymoma mimicking poorly differentiated thyroid carcinoma: Diagnostic pitfalls of anterior mediastinal mass fine needle aspiration

B3 thymoma is a rare malignant type of thymic epithelial neoplasm found in the anterior mediastinum. Diagnosis of thymoma from fine needle aspiration (FNA) can be challenging due to the infrequency of sampling and its morphologic overlap with other entities such as squamous cell carcinoma, lymphoma or thyroid carcinoma. We report a case of B3 thymoma mimicking poorly differentiated thyroid carcinoma. We present its diagnostic pitfalls on cytology specimens, especially where it concerns identifying the correct location of the lesion, discuss the differential diagnosis, and correlation with the corresponding surgical resection specimen. A neck computed tomography angiogram (CTA) revealed a partially calcified 2.1 cm mass inferior to the left thyroid lobe in a 51 yr old woman being evaluated for stroke/TIA symptoms. She was referred for evaluation of the lesion. On the initial FNA and core needle biopsy, the lesion showed high-grade epithelioid cells with abundant lymphocytic infiltration and occasional necrosis, and was diagnosed as a high-grade carcinoma, favored to represent a poorly differentiated thyroid carcinoma considering the location on imaging. The patient subsequently underwent total thyroidectomy, central neck dissection, and thymectomy. Final surgical pathologic diagnosis indicated a type B3 thymoma. Due to the infrequency of sampling, thymoma poses a diagnostic challenge on preoperative FNA or core needle biopsy. Herein, we present a case of B3 thymoma with a preoperative cytologic specimen that consisted of hyperchromatic sheets of epithelioid tumor cells with a background of lymphocytes without definitive follicular cells or colloid. The core needle biopsy and cell block material showed abundant necrosis, intermixed lymphocytes and neoplastic epithelial cells with strong positive staining for pan-keratin and p40. The cytology and core needle biopsy material were interpreted as representing a probable thyroid neoplasm and raised a broad differential including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma with squamous features, metastatic squamous carcinoma, and metastatic carcinoma to a lymph node. The final surgical resection specimen showed a B3 type-thymoma.

Clinical Reasoning: A 59-Year-Old Man With Thymoma and Constitutional Symptoms, Seizures, and Multifocal CNS Lesions

A 59-year-old man first presented for an episode of left arm numbness. During workup, a thymoma was incidentally discovered and resected. The symptoms in his left arm were attributed to a cardiac pathology. One month later, he began to experience fatigue, weight loss, and anorexia, followed by one generalized tonic-clonic seizure. Workup including toxic and metabolic screening and MRI of the brain were unremarkable. He was started on an antiseizure medication and did well for 2 years, when his symptoms recurred. Repeat MRI of the brain showed multiple cortical T2-weighted fluid-attenuated inversion recovery (T2/FLAIR) hyperintense lesions without enhancement or diffusion restriction. Further workup included spinal MRI, CT of the chest/abdomen/pelvis, CSF studies, and autoimmune/paraneoplastic panels in CSF and serum, all of which were unremarkable. Serum testing was positive for striational antibodies, acetylcholine receptor (AChR)-binding antibodies, and AChR-modulating antibodies. He received high-dose steroids and plasma exchange with resolution of his symptoms and has since been stable on mycophenolate mofetil. This presentation highlights the rare association between thymoma and encephalitis. Prompt identification and treatment is critical. This article discusses the diagnostic approach to this rare presentation including essential features of the clinical presentation, appropriate workup, pertinent differential diagnoses, and key points for the treatment of these patients.

Case report: Complex paraneoplastic syndromes in thymoma with nephrotic syndrome, cutaneous amyloidosis, myasthenia gravis, and Morvan’s syndrome

Background

Apart from myasthenia gravis (MG), thymoma is associated with a wide spectrum of autoimmune paraneoplastic syndromes (PNSs). Here, we report on a rare case presenting with four different PNSs, namely, MG, membranous nephropathy, cutaneous amyloidosis, and Morvan’s syndrome associated with thymoma.

Case presentation

A middle-aged man was frequently hospitalized because of nephrotic syndrome (stage I membranous nephropathy), cutaneous amyloidosis, and MG with acetylcholine receptor (AChR) antibody and titin antibody positivity. Chest CT showed a thymic mass in the left anterior mediastinum, and he received intravenous immunoglobulin (IVIG), methylprednisolone pulse therapy, thoracoscopic thymoma resection, and radiotherapy. Postoperative pathological examination revealed a type B2 thymoma. During the perioperative stage, his electrocardiogram (ECG) showed myocardial infarction-like ECG changes; however, his levels of cardiac enzymes and troponin were normal, and he had no symptoms of precardiac discomfort. Six months after thymectomy, his nephrotic syndrome and MG symptoms were relieved; however, he presented with typical manifestations of Morvan’s syndrome, including neuromyotonia, severe insomnia, abnormal ECG activity, and antibodies against leucine-rich glioma-inactivated 1 (LGI1) and γ-amino-butyric acid-B receptor (GABABR). His symptoms did not improve after repeated IVIG and steroid therapies. Finally, he received low-dose rituximab, and his symptoms gradually resolved.

Conclusion

This case serves to remind us that apart from MG, thymoma is also associated with other autoimmune PNSs such as membranous nephropathy, cutaneous amyloidosis, and Morvan’s syndrome. Autoimmune PNSs can present concurrently with or after surgical or medical therapy for thymoma. For Morvan’s syndrome post-thymectomy with LGI1 antibody positivity, B-cell depletion therapy such as intravenous rituximab is an effective treatment.

Effect of myasthenia gravis on the surgical outcomes of patients with thymoma

BACKGROUND

Myasthenia gravis (MG) is the most common paraneoplastic syndrome in thymoma. However, the association between MG and postoperative outcomes is controversial. Therefore, we examined the effect of MG on the surgical outcomes of patients with thymoma.

METHODS

This study enrolled 145 consecutive patients with thymoma who underwent surgical resection at our institution between January 2000 and December 2020. The patients were classified into thymoma with MG (MG group) and without MG (non-MG group). Data about characteristics of patients, surgical outcomes, and prognostic factors were compared between the two groups.

RESULTS

Of 145 patients, 47 (32%) presented with MG and 98 (68%) did not. There was no significant difference in terms of the incidence of postoperative complications, overall survival (OS), and recurrence-free survival (RFS) between the two groups. The deaths were not caused by thymoma. Among the patients aged >60 years, the MG group had a lower survival rate than the non-MG group. In the univariate analysis, age ≥60 years was a poor prognostic factor for OS, whereas in the multivariate analysis, Masaoka stage III and IV classifications were poor prognostic factors for RFS.

CONCLUSION

The incidence of postoperative complications did not differ between patients with thymoma and without MG. In the MG group, age ≥60 years was a poor prognostic factor for OS. The postoperative follow-up of patients aged ≥60 years with thymoma with MG should focus on not only recurrence but also progression of diseases other than thymoma.

Identification of Immune-Related Hub Genes in Thymoma: Defects in CD247 and Characteristics of Paraneoplastic Syndrome

Background: Thymomas (Ts) and thymic carcinomas (TCs) are rare primary tumors of the mediastinum. Paraneoplastic syndrome (PNS) is an important feature of thymoma, which presents great challenges to clinicians.

Methods: The present study uses the weighted gene co-expression network analysis (WGCNA) to identify possible immunologic mechanisms of thymoma. RNA sequencing data from thymoma samples were downloaded from the TCGA. Core genes were taken from the module that is closely related to the WHO’s stage of classification. Enhanced analysis using the online database “Metascape” and an overall survival (OS) analysis were carried out via the Kaplan–Meier method. The hub genes were obtained from the protein–protein interaction (PPI) network. In addition, we jointly analyzed multiple sets of PNS data related to thymomas from other sources to verify the correlation between thymomas and PNS. The impact of hub genes on the prognosis of PNS was evaluated via the ROC curve, with simultaneous analysis of immune infiltration by CIBERSORT.

Findings: The 14 immune hub genes closely related to thymomas were found to be jointly involved in the T-cell receptor signaling pathway. Compared to the normal thymus and type B1/B2 thymoma, there is a lower number of T-cells in type A/B3 thymoma and thymic carcinoma. The expression of genes related to the T-cell receptor signaling pathway appeared defective. The low expression of CD247 and the decrease in the number of mature T-cells are common features among thymomas, specific pulmonary fibrosis, rheumatoid arthritis, and systemic lupus erythematosus.

Diagnostic Challenges in the Cytology of Thymic Epithelial Neoplasms

Simple Summary

Thymic epithelial neoplasms, including thymoma, thymic carcinoma, and thymic neuroendocrine neoplasms, constitute the majority of anterior mediastinal masses. Fine needle aspirations (FNA) of mediastinal masses are infrequently encountered and are highly challenging to interpret. Thymic neoplasms display a significant degree of histologic diversity and have overlapping morphologic features with tumors from other sites. However, when properly interpreted alongside ancillary studies and radiologic findings, FNAs can yield clinically actionable results. This review aims to illustrate the usefulness and diagnostic pitfalls of thymic FNAs to assist pathologists in analyzing these specimens.

Abstract

Thymic epithelial neoplasms are rare tumors that constitute the majority of anterior mediastinal masses. They are classified as thymomas, thymic carcinomas, and thymic neuroendocrine neoplasms. Biopsy diagnosis is not common, and most tumors are surgically resected. Biopsy, including cytology, is indicated when a non-surgical entity is suspected or in cases of locally advanced disease. Smears of thymomas consist of round or spindle epithelial cells admixed with varying amounts of lymphocytes depending on the type of thymoma. Smears of thymic carcinoma and thymic neuroendocrine neoplasms are often indistinguishable from corresponding tumor types from other organs. Accurate cytological diagnosis can be difficult due to the histological diversity of thymomas, as well as the morphological features that certain thymic tumors share with similar tumors from other organs. However, fine needle aspiration (FNA) of anterior mediastinal masses can provide clinically actionable information and can be used to determine whether lesions require surgical, systemic, or local noninvasive treatments. Ancillary studies, namely, immunocytochemical stains, flow cytometry, and radiology, are important tools in the evaluation of thymic aspirates. This review discusses the utility and limitations of thymic FNAs and illustrates the diagnostic features and pitfalls of these specimens.

Pure White Cell Aplasia and Immune Thrombocytopenia after Thymoma Resection: A Case Report and Review of the Literature

We report a case of pure white cell aplasia (PWCA) postthymoma resection in a 74-year-old male presenting with a 2-week history of fevers, night sweats, and severe febrile neutropenia. His pure white cell aplasia was treated with intravenous immunoglobulin (IVIg), granulocyte colony-stimulating factor (G-CSF), prednisone, and cyclosporine with a mixed response. He also developed immune thrombocytopenia, which responded well to a short course of eltrombopag. With continued cyclosporine treatment, his platelet counts were stable after stopping eltrombopag. The patient's cyclosporine treatment was complicated by renal failure, resulting in cessation of cyclosporine. His PWCA and immune thrombocytopenia significantly worsened after stopping cyclosporine, and unfortunately, he died from multiorgan failure and sepsis.

[Mediastinal Tumors]

If mediastinal tumours cause symptoms these are related to their anatomical localization or a paraneoplastic syndrome. The differential diagnosis is based on the clinical situation with finding the lesion, and, furthermore, taking into account the age and sex of the patient, and the mediastinal compartment where the lesion is located. Cross-sectional radiographic diagnostic is essential for defining the therapeutic strategy. The anterior mediastinum is dominated by thymic tumours, mediastinal lymphomas, germ cell tumours and ectopic mediastinal poiters. The middle mediastinal compartment is the most frequent place of mediastinal cystic tumours, whereas the posterior mediastinum is the domain of neurogenic tumours. For selected cases a tissue biopsy is required. Surgery is the mainstay for most mediastinal tumours. Median sternotomy is the most frequent conventional surgical technique while minimally invasive surgery with thoracoscopic and above all robot assisted operation techniques are increasingly frequent. Combined chemotherapy and modern radiotherapy are essential components of the comprehensive treatment for mediastinal tumours.

Gastroparesis, Thymoma, and Asymptomatic Myasthenia: A Rare Clinical Scenario

Background: Paraneoplastic gastroparesis is a gastrointestinal syndrome that rarely precedes a tumor diagnosis. To increase awareness of this rare clinical entity, we present a case of severe gastroparesis, which was later proven to be associated with a thymoma. Case report: A 55-year old man had the sudden onset of severe abdominal cramps and abdominal distension, early satiety with postprandial nausea, acid regurgitation, belching, and flatulence. He lost about 20 pounds. The physical and imaging examination revealed stomach distension, gastroparesis, and the presence of a solid mass in the anterior mediastinum. Radical surgery was performed to remove the thymoma and, given the high value of Mib-1, the patient was submitted to postoperative chest radiation therapy. After thymectomy, a diagnosis of paraneoplastic myasthenia gravis with subacute autonomic failure was made. Conclusion: Autoimmune gastroparesis should be considered as a potential paraneoplastic syndrome in patients with thymoma, myasthenia gravis, and delayed gastric emptying in the absence of mechanical obstruction.

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.

Thymoma-Related Paraneoplastic Syndrome Mimicking Reactive Arthritis

Background and Objectives: Thymomas are associated with a high frequency of paraneoplastic manifestations. Paraneoplastic syndrome (PNS) with thymoma presents a challenge to clinicians because of the need to decipher the association between the presenting symptoms and the underlying tumor. The condition most commonly noted in patients with PNS with thymoma is myasthenia gravis. Other common autoimmune diseases that may present as PNS include systemic lupus erythematosus, pure red cell aplasia, and Good syndrome. Seventy-six percent of patients with PNS-associated thymoma experience resolution of PNS after curing thymoma. Materials and Methods: A 37-year-old man with a two-month fever accompanied by polyarthritis accidently found thymoma after contrast computed tomography scans of his chest. He accepted Video assisted thoracoscopic surgery with resection of thymoma. Results: Fever and polyarthritis resolved after operation but recurred in five days due to cytomegalovirus viremia, which might be predisposed by previous antibiotics treatment before the diagnosis of thymoma. Conclusion: Patients with a thymoma also have a high frequency of PNS, and the most frequent condition found in patients with PNS-associated thymoma is myasthenia gravis. Fever with polyarthritis has been rarely reported as a symptom of PNS-associated thymoma. Here we reported an unusual case of PNS mimicking reactive arthritis with thymoma, as diagnosed based on the patient’s clinical progression, imaging examination, and laboratory tests. The patient died of his comorbidities, and his death may have been related to long-term antibiotic use and consequent intestinal dysbiosis. This challenging case may help to inform clinicians of the need for detailed work-up of fever with unknown origin in the presence of chronic polyarthritis to prevent the overdiagnosis of inflammatory arthritis or rheumatic disease and avoid further comorbidities. Detailed work-up should include the patient’s history of infections, inflammation, and malignant or nonmalignant tumors.

Thymoma associated with severe pancytopenia and Good's syndrome: case report

We report a rare case of thymoma associated with pancytopenia and Good's syndrome. The patient was a previously healthy 60-year-old female who presented to the emergency department with a severe headache. Her initial work up was significant for a parenchymal hemorrhage and severe pancytopenia. A CAT scan of her chest, abdomen, and pelvis demonstrated a large mediastinal mass and core biopsy confirmed thymoma. Bone marrow aspirate was hypocellular. Initial multidisciplinary discussion recommended immunosuppressive therapy to treat her aplastic anemia prior to resection. However, she remained transfusion-dependent from her pancytopenia and required prolonged admission. Ultimately, the patient was unable to undergo immunosuppressive therapy due to persistent infection. Hematology/oncology believed that the initial response to immunosuppressive therapy would further compromise her immune function and would be detrimental for the patient. After undergoing thymectomy, she suffered from persistent severe pancytopenia, diarrhea, and pneumonia. She remained transfusion-dependent and despite remaining on broad spectrum antimicrobials, she continued to have fevers. She was diagnosed with Good's syndrome postoperatively after she was found to be hypogammaglobulinemic. She received intravenous immunoglobulin (IVIG) immediately, but ultimately expired from multi-system organ failure. This case report highlights the importance of early diagnosis and multidisciplinary treatment for patients who have hypogammaglobulinemia, severe pancytopenia, and thymoma. We recommend early treatment of IVIG.

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.

Molecular pathology of thymomas: implications for diagnosis and therapy

Thymomas exhibit a unique genomic landscape, comprising the lowest on average total mutational burden among adult human cancers; a unique point mutation in the GTF2I gene in WHO type A and AB thymomas (and rarely others); almost unique KMT2A-MAML2 translocations in rare WHO type B2 and B3 thymomas; a unique YAP1-MAML2 translocation in almost all metaplastic thymomas; and unique miRNA profiles in relation to GTF2I mutational status and WHO histotypes. While most thymomas can be diagnosed solely on the basis of morphological features, mutational analyses can solve challenging differential diagnostic problems. No molecular biomarkers have been identified that predict the response of unresectable thymomas to chemotherapy or agents with known molecular targets. Despite the common and strong expression of PDL1 in thymomas, immune checkpoint inhibitors are rarely applicable due to the poor predictability of common, life-threatening autoimmune side effects that are related to the unrivaled propensity of thymomas towards autoimmunity.

Autoimmune disorders and paraneoplastic syndromes in thymoma

Thymomas are counted among the rare tumour entities which are associated with autoimmune disorders (AIDs) and paraneoplastic syndromes (PNS) far more often than other malignancies. Through its complex immunological function in the context of the selection and maturation of T cells, the thymus is at the same time highly susceptible to disruptive factors caused by the development and growth of thymic tumours. These T cells, which are thought to develop to competent immune cells in the thymus, can instead adopt autoreactive behaviour due to the uncontrolled interplay of thymomas and become the trigger for AID or PNS affecting numerous organs and tissues within the human body. While myasthenia gravis is the most prevalent PNS in thymoma, numerous others have been described, be they related to neurological, cardiovascular, gastrointestinal, haematological, dermatological, endocrine or systemic disorders. This review article sheds light on the pathophysiology, epidemiology, specific clinical features and therapeutic options of the various forms as well as courses and outcomes of AID/PNS in association with thymomas. Whenever suitable and backed by the limited available evidence, the perspectives from both the thymoma and the affected organ/tissue will be highlighted. Specific issues addressed are the prognostic significance of thymectomy on myasthenia gravis and other thymoma-associated AID/PND and further the impact and safety of immunotherapies on AID and PND relating to thymomas.

Incidence of AChR Ab-positive myasthenia gravis in Israel: A population-based study

BACKGROUND

The incidence of myasthenia gravis (MG) has traditionally been low, ranging between 2-6/10⁶ . Several recent epidemiological studies have reported a higher incidence. We, therefore, aimed to assess and characterize the incidence of MG in Israel.

METHODS

We retrospectively reviewed the records of all four laboratories that performed the acetylcholine receptor antibody (AChR Ab) test in Israel between 1994 and 2013 and documented the number of newly diagnosed seropositive MG patients each year. To assure that data indeed reflect only newly diagnosed patients, patient's names and ID numbers were screened at the Hadassah medical center database since 1978, the year when the test was first performed in Israel. In order to calculate the annual incidence of the disease, the population at risk was derived from the annual publication of the Israeli Central Bureau of Statistics.

RESULTS

The annual incidence of MG for this time period was 13.1/10⁶ inhabitants. The mean incidence of MG between 1994 and 2003 was 7.695/10⁶ /y, while the mean incidence between 2004 and 2013 was 18.49/10⁶ (P < .0001). Mean age of diagnosis between 1994 and 2003 was 56.65 ± 0.9351, while between 2004 and 2013, it was 59.89 ± 0.5336 (P = .0012). Male to female (M:F) incidence ratio in the years 1994-2003 and 2004-2013 was 2:3.2 and 3:1.8, respectively, reflecting increased incidence among males (P < .0001).

CONCLUSIONS

The incidence of MG in Israel has increased significantly during the last decade, especially among males of older age. These findings may reflect an etiological role of an environmental factor, increased awareness, and increased longevity in general.