Thymoma

Ectopic Cervical Thymoma in a Patient Diagnosed With Graves Disease: A Systematic Literature Review

Thymomas are benign thymic epithelial neoplasms, rarely found outside the anterior mediastinum. Although hyperthyroid states have been associated with thymic hyperplasia, only 3 thymoma cases have been previously reported in patients with Graves disease (GD), all within the anterior mediastinum. Here, we report a case of ectopic cervical thymoma in a 22-year-old female patient previously treated for GD. The patient underwent ultrasonography, computed tomography, inconclusive fine-needle aspiration, and ultimately gross dissection for diagnostic workup and definitive treatment of an anterior neck mass, producing a 2.5 × 2.3 × 1.5-cm entity consistent with Masaoka stage I and type B2 thymoma per World Health Organization classification. The patient underwent an uncomplicated subsequent clinical course, with no adjuvant radiotherapy administered. After conducting a systematic literature review, we conclude that of the 109 cases of ectopic cervical thymoma reported, this is the first to describe a case of ectopic cervical thymoma in a patient with a past medical history of GD. For GD patients in stable euthyroid remission with the persistent or recurrent presence of an anterior neck mass, the extrathyroidal origin of the mass should always be considered, including the exceptional presence of a cervical ectopic thymoma.

PD-L1 Expression in Neoplastic and Immune Cells of Thymic Epithelial Tumors: Correlations with Disease Characteristics and HDAC Expression

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression in neoplastic and immune cells of the tumor microenvironment determines the efficacy of antitumor immunity, while it can be regulated at the epigenetic level by various factors, including HDACs. In this study, we aim to evaluate the expression patterns of PD-L1 in thymic epithelial tumors (TETs), while we attempt the first correlation analysis between PD-L1 and histone deacetylases (HDACs) expression.

METHODS

Immunohistochemistry was used to evaluate the expression of PD-L1 in tumor and immune cells of 91 TETs with SP263 and SP142 antibody clones, as well as the expressions of HDCA1, -2, -3, -4, -5, and -6.

RESULTS

The PD-L1 tumor proportion score (TPS) was higher, while the immune cell score (IC-score) was lower in the more aggressive TET subtypes and in more advanced Masaoka-Koga stages. A positive correlation between PD-L1 and HDAC-3, -4, and -5 cytoplasmic expression was identified.

CONCLUSIONS

Higher PD-L1 expression in neoplastic cells and lower PD-L1 expression in immune cells of TETs characterizes more aggressive and advanced neoplasms. Correlations between PD-L1 and HDAC expression unravel the impact of epigenetic regulation on the expression of immune checkpoint molecules in TETs, with possible future applications in combined therapeutic targeting.

Review of clinical and diagnostic imaging of the thymus: from age-related changes to thymic tumors and everything in between

The thymus, a primary lymphoid organ of the immune system, undergoes several changes due to a variety of reasons, ranging from aging to pathological conditions. These changes can make distinguishing between benign and neoplastic changes in the thymus challenging, thereby complicating the histopathological diagnoses of thymic tumors. Moreover, most patients with thymic tumors are asymptomatic at the time of diagnosis. Therefore, imaging plays an extremely important role in the evaluation of thymic lesions. In this review, we introduced the imaging characteristics of the thymus, ranging from benign findings, such as normal maturation and benign lesions, to neoplasms.

MG-Net: Multi-level global-aware network for thymoma segmentation

BACKGROUND AND OBJECTIVE

Automatic thymoma segmentation in preoperative contrast-enhanced computed tomography (CECT) images makes great sense for diagnosis. Although convolutional neural networks (CNNs) are distinguished in medical image segmentation, they are challenged by thymomas with various shapes, scales and textures, owing to the intrinsic locality of convolution operations. In order to overcome this deficit, we built a deep learning network with enhanced global-awareness for thymoma segmentation.

METHODS

We propose a multi-level global-aware network (MG-Net) for thymoma segmentation, in which the multi-level feature interaction and integration are jointly designed to enhance the global-awareness of CNNs. Particularly, we design the cross-attention block (CAB) to calculate pixel-wise interactions of multi-level features, resulting in the Global Enhanced Convolution Block, which can enable the network to handle various thymomas by strengthening the global-awareness of the encoder. We further devise the Global Spatial Attention Module to integrate coarse- and fine-grain information for enhancing the semantic consistency between the encoder and decoder with CABs. We also develop an Adaptive Attention Fusion Module to adaptively aggregate different semantic-scale features in the decoder to preserve comprehensive details.

RESULTS

The MG-Net has been evaluated against several state-of-the-art models on the self-collected CECT dataset and NIH Pancreas-CT dataset. Results suggest that all designed components are effective, and MG-Net has superior segmentation performance and generalization ability over existing models.

CONCLUSION

Both the qualitative and quantitative experimental results indicate that our MG-Net with global-aware ability can achieve accurate thymoma segmentation and has generalization ability in different tasks. The code is available at: https://github.com/Leejyuan/MGNet.

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.

Approach to Mediastinal Fine Needle Aspiration Cytology

Mediastinal fine needle aspirations are routinely encountered in cytopathology practice. Mediastinal lesions may pose diagnostic challenges owing to their rarity and locations associated with the complexity of the mediastinal anatomic structures in the thoracic cavity. Diagnosing mediastinal lesions and guiding patient management usually require correlating with clinical and radiologic findings, being familiar with cytomorphologic features and appropriately triaging the diagnostic material for ancillary testing. This review proposes a practical approach to interpret mediastinal fine needle aspirations and emphasizes potential diagnostic pitfalls for mediastinal lesions including benign cysts, thymic neoplasms, lymphoproliferative disorders, germ cell tumors, mesenchymal tumors, and metastatic tumors.

Thymoma may explain the confusion: a case report

Background

The association of inflammatory myopathy and myasthenia gravis is a rarely described entity whose clinical presentation has always been intriguing because of the great clinical similarity between these two pathologies. The presence of a thymic pathology often explains this combination, whose mechanisms are very complex.

Case presentation

A 56-year-old woman of North African origin, was hospitalized to explore the Raynaud phenomenon associated with proximal muscle weakness, pain, and arthralgia. There was no rash, and neuromuscular examination had revealed proximal tetraparesis and mild neck weakness. Tendon reflexes were normal. There was no abnormal nail fold capillaroscopy. A significant titer of muscle enzymes had been shown on blood tests, and autoimmune screening for myositis-specific and myositis-associated autoantibodies was negative. Electromyography had shown a myopathic pattern, and muscle biopsy confirmed an inflammatory myopathy. Although steroids were introduced, the clinical course was unsatisfactory; ophthalmic and bulbar symptomatology appeared. The association of myasthenia gravis was confirmed by an elevated level of serum acetylcholine receptor. A chest computed tomography scan had identified a thymoma. Treated with prednisone, pyridostigmine, and thymectomy, the patient’s clinical and biological evolution was favorable.

Conclusion

This case illustrates an exceptional association of two entities and the difficulty encountered during their diagnosis and treatment. The management of these two diseases is different, so it is essential to recognize this concomitant presentation.

Ephrin Receptors (Ephs) Expression in Thymic Epithelial Tumors: Prognostic Implications and Future Therapeutic Approaches

Ephrin receptors (Ephs) are receptor tyrosine kinases (RTKs) implicated in tissue development and homeostasis, and they are aberrantly expressed in tumors. Here, immunohistochemical Eph type-A and -B expression in thymic epithelial tumors (TETs) was assessed and correlated with clinicopathological parameters. Tissue microarrays from 98 TETs were stained for EphA1, -A2, -A4 -A6, -B1, -B2, -B4 and -B6. The relationship between neoplastic and lymphoid cell immunoreactivity score (H-score), histopathological parameters (Pearson’s test) and survival of 35 patients (Mantel-Cox model) was explored. Epithelial-rich subtypes showed higher EphA6 cytoplasmic H-score (B2/B3, carcinoma) (p < 0.001) and stronger EphA4 H-score (B3, carcinoma) (p = 0.011). The immature T-cells, especially in subtypes AB/B1, had higher EphB6 H-score than carcinoma-associated mature lymphocytes (p < 0.001); carcinomas had higher lymphocytic EphB1 H-score (p = 0.026). Higher lymphocytic and lower epithelial EphB6 H-score correlated with Masaoka stage ≤II (p = 0.043, p = 0.010, respectively). All cases showed variable epithelial and lymphocytic EphA2 expression, but clinicopathological associations were not reached. Our study confirmed that Eph type-A and -B expression in TETs is associated with established prognostic parameters, i.e., tumor subtype and Masaoka stage, although correlation with patient survival was not reached. Such findings suggest involvement of these RTKs in thymic neoplasia, as well as their potential utility as treatment targets.

Diagnostic Challenges in Fine-Needle Aspiration Cytology of Mediastinal Tumors and Lesions

CONTEXT.—

Mediastinal tumors/lesions are frequently encountered in daily cytopathology practice. These lesions are accessible through endoscopic/endobronchial ultrasound-guided or computed tomography-guided fine-needle aspiration cytology and represent a wide range of primary and metastatic tumors. This often poses diagnostic challenges because of the complexity of the mediastinal anatomic structures. Tumors metastatic to mediastinal lymph nodes represent the most common mediastinal lesions and must be differentiated from primary lesions.

OBJECTIVE.—

To provide an updated review on the fine-needle aspiration cytology of mediastinal tumors/lesions, with an emphasis on diagnostic challenges. This review encompasses thymic epithelial neoplasms, mediastinal lymphoproliferative disorders, germ cell tumors, neuroendocrine tumors, soft tissue tumors, and metastatic tumors. Differential diagnoses; useful ancillary studies, including targeted immunohistochemical panels; and diagnostic pitfalls are discussed.

DATA SOURCES.—

Data were gathered from a PubMed search of peer-reviewed literature on mediastinal tumors. Data were also collected from the authors' own practices.

CONCLUSIONS.—

Fine-needle aspiration cytology plays a vital role in evaluation of mediastinal lesions. Being familiar with the clinical and cytomorphologic features of these lesions, appropriately triaging the diagnostic material for ancillary testing, and correlating with radiologic findings are important in arriving at correct diagnoses and guiding management.

Identification of differentially expressed circular RNAs associated with thymoma

BACKGROUND

Thymomas and thymic carcinomas are the most common tumor types among anterior mediastinal lesions. However, the relationship between molecular aberrations and thymoma patients are poorly understood, especially abnormal changes in the expression profiles of circRNAs. The purpose of the present study was to investigate the expression profiles of circRNAs in thymoma patients and their possible roles in the pathogenesis of thymoma.

METHODS

Diseased tissues and surrounding normal thymic tissues in two thymoma patients were collected for circRNA sequencing. The top four upregulated circRNAs were selected as candidates and further validated with RT-PCR in 20 thymoma patients. Gene ontology and signal transduction network analyses of circRNA-related mRNAs were performed to analyze the functional properties. Survival analysis of their parental genes were also carried out to evaluate the clinical value of differentially expressed circRNA.

RESULTS

A total of 73 circRNAs were differentially expressed in thymoma tissues using high-throughput sequencing. Among these circRNAs, hsa_circ_0001173, hsa_circ_0007291, hsa_circ_0003550, and hsa_circ_0001947 were significantly upregulated in thymoma tissues compared with normal thymic tissues. We identified that these four circRNA-related mRNAs were involved in cell-cell adhesion, MAPK pathways, and TNF pathway, which may contribute to the pathological immune disorder in thymoma. Finally, we also found that SCAP (hsa_circ_0007291 parental gene) and AFF2 (hsa_circ_0001947 parental gene) were all significantly related with progression-free survival (PFS) of thymoma patients in a Kaplan-Meier plot (p-value <0.05).

CONCLUSIONS

The expression levels of hsa_circ_0001173, hsa_circ_0007291, hsa_circ_0003550, and hsa_circ_0001947 were significantly upregulated and positively correlated with immune imbalance in thymoma patients.

Thymic Epithelial Neoplasms: Tumor-Node-Metastasis Staging

Thymic epithelial neoplasms are a group of malignant tumors that includes thymoma, thymic carcinoma, and thymic neuroendocrine tumors. Although several staging systems have been developed over the years for use with these cancers, they have been interpreted and implemented in a nonuniform manner. Recently, the International Association for the study of Lung Cancer and the International Thymic Malignancy Interest Group developed a tumor-node-metastasis staging system that has been universally accepted and correlates with patient survival and outcomes. Although pathologic staging is determined by histologic examination of the resected tumor, imaging plays an important role in clinical staging and is important for informing therapeutic decisions.

Thymolipoma associated with lymphocytosis in a 6-year-old girl: A case report

Thymolipoma is a benign and rare tumor that could be found at any age. Thymolipoma associated with the myasthenia gravis, Graves disease, aplastic anemia, and hypogammaglobulinemia was reported previously, but in this case, thymolipoma is associated with lymphocytosis. A 6-year-old girl was brought to the hospital because of a chronic cough. Her evaluation revealed a 130 × 160× 160 mm fat-containing soft tissue mass arising from anterior mediastinum with complete left lung collapse and contralateral mediastinal shift. Her past medical history showed that she had been evaluated and treated unsuccessfully due to severe lymphocytosis two years earlier. Her peripheral blood and bone marrow cell morphology were normal; in contrast, blood cell count and CD flow cytometry showed severe lymphocytosis. The patient's tumor was excised entirely without any complications, and lymphocytosis resolved during the follow-up period. Because the T lymphocytes are developed in the thymus, and more than 80% of cells in CD flow cytometry were T lymphocytes, and the lymphocytosis resolved with tumor removal; therefore, the authors suggested that Thymolipoma could be associated with lymphocytosis.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Current Role of 111In-DTPA-Octreotide Scintigraphy in Diagnosis of Thymic Masses

Aims and background

Thymic tumors (thymomas and thymic carcinomas) represent 50% of all mediastinal tumors. Thymomas usually express high levels of somatostatin receptors, which enable in vivo imaging with 111In-DTPA-octreotide (OctreoScan®). The aim of this study was to further investigate the role of radionuclide techniques in the diagnosis, staging and follow-up of these tumors.

Methods

Eight patients (5 women, 3 men, age range 35–79 years; mean ± SD 56.1 ± 15.8 years) entered the study. In 4 patients, myasthenia gravis was the presenting symptom. 111In-DTPA-octreotide scan was performed within 3 weeks after contrast enhanced CT and/or MRI. Planar and tomographic images were acquired within 24 hours of the injection of 111 MBq OctreoScan. The scintigraphic results were defined in correlation with the histological findings.

Results

Histology revealed thymoma in 3 patients, thymic carcinoma in 1, insular carcinoma of presumably thymic origin in 1, thymic carcinoid in 1, and thymic hyperplasia in 2 patients. Two thymomas were at stage I, 1 thymoma and 1 thymic carcinoma at stage II, 1 insular carcinoma of presumably thymic origin at stage IV, and 1 thymic carcinoid at stage IV. OctreoScan consistently accumulated in primary and/or metastatic sites of thymic tumors while no radiotracer uptake was detected in the 2 patients with benign thymic hyperplasia. In 1 patient with a very large mediastinal mass (13 cm in largest diameter) and multiple metastatic deposits in the lungs, OctreoScan scintigraphy showed a large area of pathological uptake in the anterior mediastinum and a small area of focal uptake in the cervical-dorsal region of the right lung corresponding to a lymph node expressing somatostatin receptors.

Conclusions

OctreoScan is avidly taken up by thymic tumors, enabling the diagnosis of these tumors and a better evaluation of their extension. It does not accumulate in thymic hyperplasia, thus allowing the differential diagnosis between these 2 pathological conditions. In patients affected by myasthenia gravis, OctreoScan scintigraphy can play an important role in characterizing thymic masses.

State of the Art: MR Imaging of Thymoma

Thymoma is the most common primary malignancy of the anterior mediastinum and the most common thymic epithelial neoplasm, but it is a rare tumor that constitutes less than 1% of adult malignancies. Computed tomography (CT) is currently the imaging modality of choice for distinguishing thymoma from other anterior mediastinal masses, characterizing the primary tumor, and staging the disease. However, magnetic resonance imaging is also effective in evaluating and characterizing anterior mediastinal masses and staging thymoma in patients with contraindications to contrast-material-enhanced CT such as contrast allergy and/or renal failure.

About thymic carcinomas: challenges in diagnosis and management

BACKGROUND

Thymic carcinomas are rare tumors with a challenging diagnosis. Our aim was to report our 17-year experience of these tumors and to highlight the challenges encountered and the main differential diagnoses ruled out.

METHODS

We studied 12 (92%) men and 1 (7.7%) woman with a mean age of 37 years (range 15-60 years). All patients were symptomatic, with chest pain representing the most frequent symptom. Radiology revealed anterior mediastinal masses in all cases, with either infiltration of the adjacent organs or pulmonary parenchymal metastases.

RESULTS

The diagnosis was made on surgical biopsies in 12 cases and a lymph node biopsy in one. Microscopic examination revealed squamous carcinoma in 3 cases, synovial sarcoma in 1, mucinous adenocarcinoma in 1, undifferentiated carcinoma in 2, clear cell carcinoma in 1, lymphoepithelioma-like carcinoma in 2, atypical carcinoid tumor in 2, and sarcomatoid carcinoma in 1. Total surgical resection was possible in one patient after neoadjuvant chemotherapy and radiotherapy. Follow-up was possible in only 6 patients, and the mean survival reached 13 months.

CONCLUSION

In spite of the lack of follow-up information, this study demonstrates the poor outcome associated with these tumors and the need for standardized treatment.

Aberrant decrease of microRNA19b regulates TSLP expression and contributes to Th17 cells development in myasthenia gravis related thymomas

Myasthenia gravis (MG) is an organ-specific autoimmune disease. The imbalance of T helper type 17 cells (Th17) plays a key role in the pathogenesis of thymomatous MG. But the regulatory mechanism for Th17 cell development in MG-related thymoma remains undefined. Here we demonstrated that thymic stromal lymphopoietin (TSLP) is significantly decreased in thymomas. We also proved that TSLP was post-trancriptionally regulated by microRNA-19b. The expression of microRNA-19b was negatively correlated with the expression of TSLP mRNA and protein in thymomas. This study indicated that the elevation of microRNA-19b suppressed TSLP expression and then influenced T cell development in thymomatous MG.

Cytokine profiles contribute to understanding the pathogenic difference between Good syndrome and oral lichen planus: two case reports and literature review

We described and analyzed the pathogenic difference between Good syndrome (GS) and oral lichen planus (OLP) in oral mucosa. Good syndrome (GS) is a rare disease characterized by B and T cell immunodeficiency associated with hypogammaglobulinemia and thymoma. GS patients frequently develop oral lichenoid lesions with lymphocytic infiltration beneath the basal layer. Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa characterized by destruction of basal cells by Langerhans cells, macrophages, and T lymphocytes. Although the histological features of the lesions of both diseases are very similar, the pathogenesis of GS in the oral mucosa remains unknown. In this study, we thus investigated the expression of infiltrating lymphocyte subsets (CD3, CD20, CD4, and CD8) and T helper (Th) cytokines including interferon (IFN)-γ (Th1 type), interleukin (IL)-4 (Th2 type), IL-17 (Th17 type), and IL-10 (regulatory T cell type) by immunohistochemistry in buccal mucosa specimens from 2 GS patients compared with 15 OLP patients. All patients showed a predominance of CD3 T cells over CD20 B cells, and CD4 Th cells over CD8 cytotoxic T cells. This polarization was especially prominent in GS. IFN-γ and IL-10 were strongly detected in the infiltrating lymphocytes of all patients. However, IL-4 and IL-17 were detected in OLP patients only. These results suggest that the pathogenesis of GS is different from that of OLP. GS is a unique inflammatory disorder characterized by dysfunction of Th2 and Th17 immune reactions via abnormal T-B cell interaction.

Perioperative management in myasthenia gravis: republication of a systematic review and a proposal by the guideline committee of the Japanese Association for Chest Surgery 2014

Thymectomy is regarded as a useful therapeutic option for myasthenia gravis (MG), though perioperative management in MG patients is largely empirical. While evidence-based medicine is limited in the perioperative management of MG patients, treatment guidelines are required as a benchmark. We selected issues faced by physicians in clinical practice in the perioperative management of extended thymectomy for MG, and examined them with a review of the literature. The present guidelines have reached the stage of consensus within the Japanese Association for Chest Surgery.

Muscle autoantibodies in myasthenia gravis: beyond diagnosis?

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction. A number of molecules, including ion channels and other proteins at the neuromuscular junction, may be targeted by autoantibodies leading to abnormal neuromuscular transmission. In approximately 85% of patients, autoantibodies, directed against the postsynaptic nicotinic acetylcholine receptor can be detected in the serum and confirm the diagnosis, but in general, do not precisely predict the degree of weakness or response to therapy. Antibodies to the muscle-specific tyrosine kinase are detected in approximately 50% of generalized myasthenia gravis patients who are seronegative for anti-acetylcholine receptor antibodies, and levels of anti-muscle-specific tyrosine kinase antibodies do appear to correlate with disease severity and treatment response. Antibodies to other muscle antigens may be found in the subsets of myasthenia gravis patients, potentially providing clinically useful diagnostic information, but their utility as relevant biomarkers (measures of disease state or response to treatment) is currently unclear.

Invasive thymoma with venous intraluminal extension: CT and MRI findings

We herein report an unusual case of invasive thymoma with venous intraluminal extension. The thymoma extended into the superior vena cava, the left brachiocephalic vein, and the proximal portion of the left jugular and subclavian veins intraluminally. It was suggested that the tumor had a discrete intravascular growth via the thymic vein into the left brachiocephalic vein and extended into the proximal portion of the left jugular and subclavian veins in the opposite direction of the venous stream.

Myasthenia gravis: a review

Acquired myasthenia gravis is a relatively uncommon disorder, with prevalence rates that have increased to about 20 per 100,000 in the US population. This autoimmune disease is characterized by muscle weakness that fluctuates, worsening with exertion, and improving with rest. In about two-thirds of the patients, the involvement of extrinsic ocular muscle presents as the initial symptom, usually progressing to involve other bulbar muscles and limb musculature, resulting in generalized myasthenia gravis. Although the cause of the disorder is unknown, the role of circulating antibodies directed against the nicotinic acetylcholine receptor in its pathogenesis is well established. As this disorder is highly treatable, prompt recognition is crucial. During the past decade, significant progress has been made in our understanding of the disease, leading to new treatment modalities and a significant reduction in morbidity and mortality.

Thymic neoplasms: a clinical update

Thymoma is a unique neoplasm of the anterior mediastinum that is frequently associated with indolent growth and a variety of paraneoplastic syndromes. One third of cases are detected during the evaluation of myasthenia gravis. Classification systems of thymoma have limited ability in accurately predicting prognosis and course of disease. Thus, staging is the only way to predict clinical behavior. Encapsulated tumors that are surgically resected carry the best prognosis. Adjuvant radiotherapy is recommended for incompletely excised and most invasive thymomas. Chemotherapy in anthracycline-based chemotherapy remains the most effective chemotherapy for neoadjuvant, adjuvant or palliative treatment.

T helper type 17 cells expand in patients with myasthenia-associated thymoma

Myasthenia gravis (MG) is a prototypical CD4(+) T cell-dependent autoimmune disease mediated by anti-acetylcholine receptor autoantibodies (AChR-Abs). Certain subsets of helper T cells are suggested to be involved in the pathogenesis of MG, including Th1 and regulatory T cells (Treg). However, whether the recently identified Th17 cells play a role in the development of MG and its prognosis is still unknown. Here, we demonstrated that Th17 cells and their associated cytokines are increased, while the Treg cells are decreased in the peripheral blood mononuclear cells (PBMCs) from MG patients with thymomas (TM), but not from those with normal thymus (NT) or thymic hyperplasia (TH). Furthermore, the quantity of Th17 cells correlates with the quantitative myasthenia gravis (QMG) score in patients with TM. We also found a significant positive relationship between the frequency of Th17 cells (%) and the concentration of AChR antibodies in patients with MG. Therefore, the Th17/Treg imbalance in TM may suggest MG with certain pathological subtype, and the increase in Th17 cells may reveal the severity of the disease, which is valuable in the diagnosis and choice of therapeutic strategy for patients with MG.

Patients with thymomas have an increased risk of developing additional malignancies: lack of immunological surveillance?

AIMS

To assess the risk, for patients with thymoma, of developing an additional malignancy (AM).

METHODS AND RESULTS

We studied 68 patients with thymomas. Based on the World Health Organization classification, the tumours were categorised as A, AB or B (B1, B2, B3) thymomas. Control populations comprised 114 patients with colorectal cancer, 108 patients with lymphoma and 123 patients with thyroid carcinoma. Patients with thymomas showed a higher risk of developing an AM (22 of 68 patients versus 11 of 114, eight of 108, and eight of 123 patients, respectively; P = 0.0002). The association between thymomas and AMs was related to the thymoma histotype, with B1, B2, B3 and AB tumours showing a higher risk of developing an AM than A thymomas (P = 0.0474).

CONCLUSIONS

Patients affected by thymomas showed a significantly higher risk of developing additional malignancies than those in the control groups, and cases that exhibited a predominantly cortical component were more likely to develop other neoplasms. This may be related to the functions of cortical thymic epithelial cells in providing for T lymphocyte maturation through interaction with major histocompatibility complexes.

Thymoma in children: report of 2 cases and review of the literature

Thymoma is an uncommon and slow-growing neoplasm. It is derived from thymic epithelial cells and comprises about 20% to 30% of mediastinal masses in adults, but only about 1% in pediatric patients. Patients usually present with mass-associated respiratory symptoms, superior vena cava syndrome, or paraneoplastic syndrome including myasthenia gravis, pure red cell aplasia, or acquired hypogammaglobulinemia, and connective tissue disorders. Due to the limited number of cases, knowledge, and experience with thymoma in pediatric patients, the diagnosis and treatment are very challenging for this age group. In this article, we report 2 cases of thymoma in childhood and provide a comprehensive review and analysis of the reported pediatric cases in the past 30 years (total of 32 cases). We found that patients younger than age 10 years were predominantly male (M:F = 6:1) and had advanced tumor stage more frequent than patients older than age 10 (P = .03). There were also significant associations of male sex with more advanced tumor stage and less favorable outcome (P = .03). These findings suggest that age and sex may be additional potential prognostic contributors in pediatric patients with thymoma. The clinicopathologic features, differential diagnosis, and current therapeutic recommendations of this uncommon tumor in pediatric patients are also addressed.

Stage III thymic epithelial neoplasms are not homogeneous with regard to clinical, pathological, and prognostic features

INTRODUCTION

The main therapeutic approach to a Masaoka stage III thymic epithelial neoplasm (TEN) is surgical resection, and the 5-year survival rate is approximately 60%. According to the Masaoka staging system, invasion of neighboring organs is classified as stage III disease, regardless of the number of organs involved or the size of the tumor. We retrospectively analyzed the prognostic significance associated with the extent of disease in patients with Masaoka stage III TENs.

METHODS

From 1995 to 2006, 241 patients were identified with thymomas. Among these patients, 59 were diagnosed with Masaoka stage III disease. The patients with a stage III TEN were advised to have extended thymectomy with en bloc resection of the invaded structures as the initial treatment. The prognostic significance of the size, organs invaded, and other factors were analyzed.

RESULTS

The overall survival rates for the stage III patients were 83% and 64%, and the recurrence-free survival rates were 56% and 51%, at 5 and 8 years, respectively. Patients with a low-grade World Health Organization classification (p = 0.0202) or a complete resection (p < 0.0001) had a better overall survival. In addition, patients with tumors less than 6.5 cm (p = 0.0311) or with pericardium invasion (p = 0.0299) had a better recurrence-free survival. The patients with limited disease had a better prognosis for a recurrence-free survival than did patients with extensive disease (p = 0.0007).

CONCLUSIONS

Heterogeneous prognostic subgroups based on tumor size and organs invaded were identified in patients with Masaoka stage III TENs. Therapeutic plans, based on these subgroups, will potentially improve patient management and treatment outcomes.

Good's syndrome remains a mystery after 55 years: A systematic review of the scientific evidence

Good syndrome (GS) is a rare association of thymoma and immunodeficiency first described more than 50 years ago. However, this syndrome still remains a mystery to clinicians. We systematically reviewed all the clinical, laboratory and immunologic findings from 152 patients with Good syndrome. The syndrome has a worldwide distribution and approximately half of the cases (47%) have been described in Europe. The diagnosis of thymoma preceded the diagnosis of hypogammaglobulinemia, infection, or diarrhea in 42% of patients whereas in 38% of patients the diagnoses were made almost simultaneously within 2 months of each other. We found significant mortality in patients with this syndrome (44.5%). Astute clinical acumen and increased awareness about the clinical and immunological profile of this syndrome may increase early recognition of this syndrome and prevent mortality. Further studies are needed to elucidate this clinical entity.

[Epithelial tumours of the thymus]

Epithelial tumours of the thymus include thymomas, thymic carcinomas and neuro-endocrine tumours. Rare, they nevertheless represent 20% of all mediastinal tumours and 50% of those located in the anterior mediastinum. Thymomas, in particular, can be associated to auto-immune disorders, among which predominates myasthenia gravis. Their clinical behaviour varies widely, from a relative indolence to the potential of lymph node and/or systematic metastases. However, even patients with an invasive disease may have a long clinical history, explaining that a 10-year or 20-year survival from diagnosis does not imply a definitive cure. In daily practice, both the clinical Masaoka's staging system and the WHO histological classification condition the treatment strategies and allow to anticipate the prognosis. The initial treatment, as well as that of the recurrence, is based mainly on a complete resection. Postoperative radiotherapy is systematically added to the treatment of invasive tumours and/or to those with an aggressive histological subtype. Inoperable or metastatic tumours require a cisplatine and anthracyclin-based chemotherapy, followed by radical surgery and/or radiotherapy.

An Atypical Presentation of Thymoma with Diffuse Pleural Dissemination Mimicking Mesothelioma

Although rare, thymoma is the most frequent type of malignancy in the anterior mediastinum. On most occasions, radiological diagnosis is easy, owing to current imaging studies like computerized tomography. Additionally, the radiological diagnosis of thymoma can be differentiated easily from malignant pleural mesothelioma in most cases. However, thymoma's differentiation from lymphoma, thymic hyperplasia, or thymic remnants sometimes may pose diagnostic challenges. Here, we report a case of advanced thymoma mimicking malignant pleural mesothelioma, with circumferential encasement of the lung. A brief review of the literature with special reference to radiological imaging on thymoma also is presented.

Autoimmune myasthenia gravis: emerging clinical and biological heterogeneity

Acquired myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction in which patients experience fluctuating skeletal muscle weakness that often affects selected muscle groups preferentially. The target of the autoimmune attack in most cases is the skeletal muscle acetylcholine receptor (AChR), but in others, non-AChR components of the neuromuscular junction, such as the muscle-specific receptor tyrosine kinase, are targeted. The pathophysiological result is muscle endplate dysfunction and consequent fatigable muscle weakness. Clinical presentations vary substantially, both for anti-AChR positive and negative MG, and accurate diagnosis and selection of effective treatment depends on recognition of less typical as well as classic disease phenotypes. Accumulating evidence suggests that clinical MG subgroups might respond differently to treatment. In this Review, we provide current information about the epidemiology, immunopathogenesis, clinical presentations, diagnosis, and treatment of MG, including emerging therapeutic strategies.

Genetic markers of mediastinal tumors

Determination of the genetic markers by the application of new genomic methodologies has provided important insight into the pathogenesis of mediastinal disease. These new techniques have enabled scientists to uncover differential gene expression patterns between subtypes of thymomas, correlate tumor marker expression with germ cell tumors, and determine a link between the NF-kappaB and JAK/STAT pathways with Hodgkin's and non-Hodgkin's lymphoma. Despite the progress made in the understanding of genetic markers of select mediastinal tumors, significantly more investigation is required to elucidate the molecular pathways involved in the pathogenesis of these tumors.

Treatment of advanced thymoma and thymic carcinoma

Although thymic epithelial tumors are rare, they are relatively common among neoplasms of the anterior superior mediastinum. They usually exhibit indolent behavior, but do have the capacity to invade surrounding structures and metastasize to distant sites. Thymic carcinomas are rare, but are highly aggressive tumors that are associated with a poor prognosis. The mainstay of therapy is complete surgical resection. Locally advanced thymoma and thymic carcinoma require a multimodality treatment approach with a combination of surgery, chemotherapy, and radiation therapy to decrease the chances of recurrence and improve survival. The risk of disease recurrence lasts for a number of years after completion of primary therapy. A majority of cases of recurrent disease present as pleural recurrences. Once again, surgical resection of recurrent disease represents the cornerstone of successful therapy and is critical to long-term survival. In recent years, a better understanding of the biologic basis of thymic epithelial tumors has led to the emergence of targeted therapy directed against this malignancy.

Surgical treatment of thymic epithelial neoplasms

Resection continues to be the mainstay of treatment for epithelial lesions of the thymus. This has never been in doubt for encapsulated stage I and II lesions, but we recently have come to a greater appreciation of the role of preoperative therapy for locally advanced lesions, particularly stage III disease. For any lesion that presents in the anterior mediastinum and on CT scan does not appear to be eminently resectable, a biopsy should be performed to rule out lymphoma after serum germ cell markers have been obtained to rule out the rare primary mediastinal or metastatic germ cell tumor.