Type B3 Thymoma Research Articles

Invasive thymoma with intravascular growth into the great veins and right atrium: A case report

Here, we present a case of invasive thymoma with intraluminal growth into the left and right brachiocephalic veins, superior vena cava and the right atrium. Resection of the mass, double partial upper lobe lobectomy and superior vena cava, and left and right brachiocephalic vein replacement were performed. Pathological diagnosis indicated a mixed histological pattern indicative of type B1 and type B2 thymoma, predominantly type B2 thymoma. The patient was well and without local recurrence or distal metastasis after 50 months of follow‐up.

Immunotherapeutic potential of CD4 and CD8 single-positive T cells in thymic epithelial tumors

Indications for current immune checkpoint inhibitors are expanding and now include thymic epithelial tumors (TETs). Although clinical trials on immune checkpoint inhibitors for TETs are ongoing, a rationale has not yet been established for immunotherapy for TETs. Therefore, we herein performed phenotypic and functional analyses of T cells in surgically resected TET tissues with a focus on the anti-tumor properties of T cells to TETs as a step towards establishing a rationale for immunotherapy for TETs. We examined T-cell profiles in surgically resected TET tissues, particularly CD4 and CD8 single-positive T cells, using flow cytometry. In the functional analysis of T cells in TETs, we investigated not only cytokine production by T cells, but also their cytotoxicity using bispecific T-cell engager technology. The cluster analysis of T-cell profiles based on flow cytometric data revealed that type B3 thymoma and thymic carcinoma (B3/C) belonged to the hot cluster characterized by a high proportion of Tim-3+ and CD103+ in CD4 and CD8 single-positive T cells. Enhancements in cytokine production and the cytotoxicity of T cells by the anti-PD-1 antibody were significantly greater in B3/C. These results indicate the potential of immunotherapy for patients with B3/C.

Bone morphogenetic protein-7 expression reflects the high proliferative ability and aggressiveness of thymic epithelial tumors.

BackgroundBone morphogenetic protein-7 (BMP-7) is a transforming growth factor-β superfamily member. We examined whether BMP-7 expression in thymic epithelial tumors is associated with their clinicopathological features.MethodsOne hundred and thirty-two clinical specimens were analyzed in this study. The expression of BMP-7 was detected using immunohistochemistry and was scored as 0, 1, 2, or 3 according to its intensity and was then classified as negative (score 0 and 1) or positive (2 and 3). In addition, Ki-67 staining was performed in type B3 thymoma and thymic cancer.ResultsThe positive ratio of BMP-7 was 80% in thymic cancer and 70% in thymoma type B3. In contrast, the positive ratios of BMP-7 in type B2 (29.1%), B1 (3.7%), AB (26%), and A (31%) were relatively low. The mean Ki-67 labeling index of the BMP-7 positive group (10.1%±5.9%) was significantly higher than that of the BMP-7 negative group (4.9%±5.9%) in type B3 thymoma and thymic cancer (P=0.012). The BMP-7 positive group showed significantly poorer overall survival (OS) than the BMP-7 negative group across all patients with thymic epithelial tumors and in all types of thymomas (P=0.006, P=0.018); however, no difference was observed in thymic cancers.ConclusionsThis study showed that high expression of BMP-7 correlated with a poor prognosis in patients with thymic epithelial tumors, and the expression of BMP-7 was higher in type B3 thymomas and thymic cancers than in other types of thymomas. BMP-7 might serve as a novel prognostic biomarker for thymic epithelial tumors.

Pan-Cancer Landscape Analysis Reveals Recurrent KMT2A-MAML2 Gene Fusion in Aggressive Histologic Subtypes of Thymoma.

Thymomas are epithelial neoplasms that represent the most common thymic tumors in adults. These tumors have been shown to harbor a relatively low mutational burden. As a result, there is a lack of genetic alterations that may be used prognostically or targeted therapeutically for this disease. Here, we describe a recurrent gene rearrangement in type B2 + B3 thymomas. A single index case of thymoma was evaluated by an RNA-based solid fusion assay. Separately, tissues from 255,008 unique advanced cancers, including 242 thymomas, were sequenced by hybrid capture-based next-generation DNA sequencing/comprehensive genomic profiling of 186 to 406 genes, including lysine methyltransferase 2A (KMT2A) rearrangements, and a portion were evaluated for RNA of 265 genes. We characterized molecular and clinicopathologic features of the pertinent fusion-positive patient cases. We identified 11 patients with thymomas harboring a gene fusion of KMT2A and mastermind-like transcriptional coactivator 2 (MAML2). Fusion breakpoints were identified between exon 8, 9, 10, or 11 of KMT2A and exon 2 of MAML2. Fifty-five percent were men, with a median age of 48 years at surgery (range, 29-69 years). Concurrent genomic alterations were infrequent. The 11 thymomas were of B2 or B3 type histology, with 1 case showing foci of thymic carcinoma. The frequency of KMT2A-MAML2 fusion was 4% of all thymomas (10 of 242) and 6% of thymomas of B2 or B3 histology (10 of 169). KMT2A-MAML2 represents the first recurrent fusion described in type B thymoma. The fusion seems to be specific to type B2 and B3 thymomas, the most aggressive histologic subtypes. The identification of this fusion offers insights into the biology of thymoma and may have clinical relevance for patients with disease refractory to conventional therapeutic modalities.

Expression of molecules of the Wnt pathway and of E-cadherin in the etiopathogenesis of human thymomas.

The molecular pathogenesis of thymoma remains largely unknown. It has been recently demonstrated, that activation of Wnt signaling pathway leads to increased incidence of thymoma in murine models. The present study investigated the activation of molecules of the Wnt signaling pathway in human thymoma. A total of 112 thymoma cases with complete clinical and follow-up data and 8 controls were included in the present study. Patients with thymoma and controls were examined immunohistochemically for β-catenin and E-cadherin. The mRNA expression levels of CTNNB1, CCND1, MYC, AXIN2 and CDH1 were analyzed by reverse transcription-quantitative PCR. Immunohistochemically, β-catenin and E-cadherin were overexpressed in neoplastic cells of all thymomas. In type A, B1 and non-invasive type B2 thymoma, both molecules were located in the cytoplasm, in contrast to invasive type B2 and B3 thymoma, where membranous immunopositivities were observed. mRNA expression levels of genes involved in the Wnt pathway and of E-cadherin were significantly increased in both type A and B thymoma compared with controls; increasing gradually from type B1 to B3, and with higher stage of disease. In recurrent type B thymoma, the mRNA expression of the molecules was significantly higher. Despite the activation of Wnt pathway in indolent type A thymoma, the negative feedback of the pathway was preserved by overexpression of inhibitory molecule axin2, which was not overexpressed in type B thymoma. In summary, the Wnt pathway was activated in human thymoma and may contribute to oncogenesis. Detection of molecules of the Wnt pathway may be of diagnostic and prognostic value.

A Case of Paraneoplastic Encephalitis Arising from Concurrent Thymoma and Stage I Adenocarcinoma of the Lung

Paraneoplastic Encephalitis (PE) is a rare syndrome that arises as a tumor-induced autoimmune response which can cause focal or diffuse nervous system dysfunction. Patients commonly present with a variety of neurologic symptoms, depending on the inflammatory distribution, and possibly with other symptoms stemming from the primary cancer. We herein present a never-smoker patient who presented with dysarthria, dysphagia and cognitive decline, and required numerous diagnostic examinations, sometimes invasive ones, for correct staging and diagnosing of the primary malignancy. Of note, despite the lack of clear evidence suggesting metastatic disease based on neuroimaging, a brain biopsy was nonetheless performed for diagnostic purposes. The patient was diagnosed with paraneoplastic encephalitis stemming from two independent primary cancers: an early stage lung adenocarcinoma and a concomitant type B3 thymoma. In addition to displaying a unique case of a paraneoplastic disorder associated with two simultaneous cancers, this report highlights the diagnostic challenge of paraneoplastic encephalitis and discusses important imaging findings with the goal of preventing invasive and evitable brain biopsies in similar future cases.

A Recurrence Predictive Model for Thymic Tumors and Its Implication for Postoperative Management: a Chinese Alliance for Research in Thymomas Database Study.

Our aim was to investigate appropriate postoperative management based on the risk of disease recurrence in thymic epithelial tumors after complete resection. The Chinese Alliance for Research in Thymomas retrospective database was reviewed. Patients having stage I to IIIa tumors without pretreatment and with complete resection were included. Clinicopathologic variables with statistical significance in the multivariate Cox regression were incorporated into a nomogram for building a recurrence predictive model. A total of 907 cases, including 802 thymomas, 88 thymic carcinomas, and 17 neuroendocrine tumors, were retrieved between 1994 and 2012. With a median follow-up of 52 months, the 10-year overall survival rate was 89.5%. Distant and/or locoregional recurrences were noted in 53 patients (5.8%). The nomogram model revealed histologic type and T stage as independent predictive factors for recurrence, with a bootstrap-corrected C-index of 0.86. On the basis of this model, patients with T1 thymomas or T2 or T3 type A, AB, or B1 thymomas had a significantly lower incidence of recurrence (low-risk group) than those with T2 or T3 type B2 or B3 thymomas and all thymic carcinomas and neuroendocrine tumors (high-risk group) (2.7% versus 20.1% [p < 0.001]). In the high-risk group, more than half of the recurrences (55.2% [16 of 29]) were seen within the first 3 postoperative years, whereas all recurrences but one were recorded within 6 years after surgery. Recurrence occurred quite evenly over 10 postoperative years in the low-risk group. A 6-year active surveillance should be considered in high-risk patients regardless of adjuvant therapy. For low-risk patients, annual follow-up may be sufficient. Studies examining postoperative adjuvant therapies would be plausible in high-risk patients.

Coexistence of Type B3 Thymoma and Bronchogenic Cyst

Coexistence of Type B3 Thymoma and Bronchogenic Cyst

Anti-\u03b1-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor GluR2 encephalitis in a myasthenia gravis patient with complete thymectomy: a case report

BackgroundAutoimmune encephalitis (AE) is a newly recognized autoimmune disorders in which the targets are proteins or receptors involved in synaptic transmission and neuronal excitability. α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is a subtype of glutamate receptor that mediates most of the fast excitatory neurotransmission in the brain.Case presentationA 50-year-old woman presented with subacute onset of memory loss and behavioral changes. High levels of serum (1:1000) and CSF (1:32) antibodies against the AMPAR GluR2 were detected. A wide range of abnormalities in 6–8 Hz low to middle slow waves was found by electroencephalographs, and high-intensity signals on fluid-attenuated inversion recovery in both the medial temporal lobe and hippocampus were identified on brain magnetic resonance images. This patient presented with myasthenia gravis and type B2 thymoma (World Health Organization Thymoma Classification) at age 48. This case was unique in that the patient initiated with the symptom of myasthenia gravis and thymoma two years prior to encephalitis, and a complete thymectomy was performed before AE onset without recurrence of the thymoma when encephalitis occurred.ConclusionsThymoma was reported to be associated with paraneoplastic neurological disease. This is the first time a thymectomy has been applied in a myasthenia gravis patient with thymoma two years prior to the onset of anti-AMPAR2 encephalitis. This case highlights the complexity of autoimmune encephalitis associated with thymoma.

Trans-subxiphoid robot-assisted thoracoscopic surgery for resecting multiple thymomas: a case report

Among thymomas, multiple thymoma (MT) is known to be a quite rare disease. For resecting MT, trans-subxiphoid robot-assisted thoracoscopic surgery (RATS) was performed. Two resected tumors were found to be type B1 and B2 thymomas, which were diagnosed to be multicentric development type MTs. Minimally invasive surgery was reported to be realized by trans-subxiphoid RATS.

Primary mediastinal neoplasms: a report of 1,005 cases from a single institution.

This study was an epidemiological analysis of all primary mediastinal neoplasms (PMNs) diagnosed between 2000 and 2016 at the National Tuberculosis and Lung Diseases Research Institute, Poland. All patients with any mediastinal abnormality were included in the analysis. The patients' age and gender were obtained from the institutional database. From a cohort of 5,108 patients, 3,691 primary mediastinal lesions were found, including 1,005 (19%) PMNs: lymphomas (533, 53% of PMNs), thymomas (215, 21%), neurogenic tumors (NTs) (100, 10%), germ cell tumors (GCTs) (62, 6%), soft tissue tumors (STTs) (47, 5%) and thymic carcinomas/thymic neuroendocrine tumors (TCs/TNETs) (37 in total, 4%). The most frequent lymphomas were classical Hodgkin lymphomas [256] and primary mediastinal large B-cell lymphomas [163]. Type AB [73] predominated in thymomas and squamous cell carcinomas [9] and carcinoids [10] in TCs/TNETs. NTs encompassed mainly schwannomas [49], ganglioneuromas [21] and neurofibromas [10]. The most frequent STTs were hemangiomas [13] and lymphangiomas [11]. Lymphomas, thymomas and NT were more often in women, TCs/TNETs in men (P<0.001). Lymphomas predominated between the 2nd and 4th decade of life, NTs under the 3rd decade and thymic epithelial tumors between the 6th and 8th decade (P<0.001). There was no correlation between the subtypes of thymomas and the patients' gender (P=0.389) but it was found between histology and patients' age: in patients <30 years of age type B2 and B3 thymomas and >70 years of age AB type and micronodular thymomas with lymphoid stroma (P<0.001) predominated. In the group of GCTs half of them were malignant and these were noted exclusively in men. No correlation between subtypes of NTs or TCs/TNETs and patients' age and gender was found (P>0.05). PMNs are rare conditions thus awareness of basic epidemiology may be very helpful for final diagnosis.

Genetic characterization of thymoma

Thymoma represents the most common anterior mediastinal compartment neoplasm, originating from the epithelial cell population in the thymus. Various histological types of thymoma feature different clinical characteristics. Furthermore, thymoma is frequently associated with autoimmune disorders, esp. myasthenia gravis (MG). However, the underlying molecular tumourigenesis of thymoma remains largely unknown. The goal of our current study is to demonstrate the underlying genetic abberations in thymoma, so as to understand the possible cause of MG in thymoma patients. By using CapitalBio mRNA microarray analysis, we analyzed 31 cases of thymoma including 5 cases of type AB thymoma, 6 B1-type cases, 12 B2-type cases, 5 B2B3-type cases and 3 type-B3 cases. 6 cases of thymoma were not associated with myasthenia gravis, while 25 cases were with myasthenia gravis. By comparisons between thymoma and the paratumoral tissues, differentially expressed genes were identified preliminarily. Among them, 292 genes increased more than 2-fold, 2 genes more than 5-fold. On the other hand, 596 genes were decreased more than 2-fold, 6 genes more than 20-fold. Interestingly, among these genes upregulated more than 2-fold, 6 driver genes (FANCI, NCAPD3, NCAPG, OXCT1, EPHA1 and MCM2) were formerly reported as driver oncogenes. This microarray results were further confirmed through real-time PCR. 8 most dysregulated genes were verified: E2F2, EPHA1, CCL25 and MCM2 were upregulated; and IL6, FABP4, CD36 and MYOC were downregulated. Supervised clustering heat map analysis of 2-fold upregulated and 2-fold downregulated genes revealed 6 distinct clusters. Strikingly, we found that cluster 1 was composed of two type-B2 thymoma; and cluster 6 was three type-B2/B3 thymoma. KEGG database analysis revealed possible genetic mechanisms of thymoma and functional process. We further compared gene expression pattern between thymoma with and without MG, and found 5 genes were upregulated more than 2-fold, more than 30 genes were downregulated more than 2-fold. KEGG analysis revealed 2 important signaling pathways with more than 2-fold upregulated genes (TGF- beta signaling pathway and HTLV-I signaling pathway) as differially functioning between MG positive and negative thymomas. Real-time PCR analysis confirmed that CCL25 was upregulated; and MYC, GADD45B, TNFRSF12 downregulated in thymoma with MG. Our study thus provided important genetic information on thymoma. It shed light on the molecular bases for analyzing the functional process of thymoma and finding potential biomarkers for pathological categorizing and treatment. Our work may provide important clues in understanding possible causes of MG in thymoma patients.

Clinicopathologic Features of Thymoma With the Expression of Programmed Death Ligand 1

Programmed death ligand 1 (PD-L1) is reportedly expressed in various malignancies and is considered a prognostic factor. We attempted to reveal the usefulness of the PD-L1 expression as a prognostic factor in patients with thymoma. Eighty-one patients with thymoma who underwent surgical resection between 2004 and 2015 were retrospectively reviewed. The PD-L1 expression was evaluated by immunohistochemistry and stratified by the proportion of positive tumor cells. Strong membranous reactivity of the PD-L1 antibody in 1% or more of tumor cells was considered "positive." The association between the PD-L1 expression and the clinicopathologic features was investigated. The PD-L1 expression was positive in 22 patients (27%) and negative in 59 patients (73%). The PD-L1 positivity was significantly associated with type B2 and B3 thymoma (p < 0.001) and stage III and IV disease (p= 0.048). In addition, PD-L1 positive tumors showed a significantly higher maximum standardized uptake value than PD-L1 negative tumors (p= 0.026). The 5-year disease-free survival rate was 82% in PD-L1 positive patients and 88% in PD-L1 negative patients, showing no significant difference (p= 0.57). Furthermore, PD-L1 positivity was not an independent prognostic factor for the disease-free survival on a Cox proportional hazards analysis (p= 0.59). A strong expression of PD-L1 in thymoma was significantly associated with type B2 and B3 and higher pathologic stages. In addition, PD-L1 positivity was associated with an increased maximum standardized uptake value of the tumor. However, patients with PD-L1 positive thymomas did not show a significantly worse prognosis than patients with PD-L1 negative tumors.

PC03.07 Adjuvant Chemotherapy for Thymic Carcinoma - YES

The role of postoperative treatment in thymic carcinoma is still a controversial issue, because of the low level evidence supporting clinical management of this cancer, made of cohort studies, retrospective studies and case reports, but no randomized clinical trials. Stage is not the only factor we should consider when the choice of postoperative chemotherapy is discussed; completeness of resection and histologic subtype have their own relevance. Thymic carcinoma accounts for about 20% of all thymic cancers, most cases diagnosed as Masaoka-Koga stage III. In this scenario, about 60% of the cases relapse at 10 years. Time of relapse and sites of disease progression should be carefully reviewed when we consider potential benefit of postoperative systemic treatment; thymic carcinomas relapse earlier and commonly at distant sites compared with thymoma, with significantly different 5 years overall survival and progression free survival. Histology preserves its association with progression free survival as radicality of resection. One reason for the controversies about the prognostic role of histology itself may be found in the difficult diagnosis of the specific subtypes as defined by WHO. Across series a complete Interobserver agreement was reported in 10 to 50% of the cases. Most difficulties seem to be the differential diagnosis among B tumors, and a better agreement was achieved when B2-B3 thymoma were grouped together with carcinoma, suggesting overlapping features among them and supporting evidence that type B3 thymomas and thymic carcinomas form a biologically different group. Complete resection of thymic carcinoma is possible in 60%-70% of the cases, achieving 5-Y and 10Y survival of 60% and 40% respectively. Type of resection and Masaoka stage seem to be correlated with survival and cumulative incidence of recurrences. However, a prognostic role of adjuvant treatment, particularly radiotherapy, is shown with possible effect not only in overall survival but also in relapse free survival. On the basis of the available data, it would be tempting to suggest a possible role for chemotherapy in R1-R2, independently by stage, preferably associated with radiation. On the other hand guidelines suggest a role for adjuvant chemotherapt in resectable thymic carcinoma R1 and, in R0 cases, in stage III or in those cases become resectable after induction chemo, independently by stage e type of resection, especially if not received before. The upcoming IASLC/ITMIG staging system, which re-defines Masaoka-Koga stage III downstaging some situations to stage I and II (as mediastinal pleural or pericardial involvement) could potentially influence adjuvant chemo in stage III thymic cancer. Stage III will be distinguished into T3, potentially resectable upfront, and T4, which might need induction chemo. Adjuvant chemoregimens may be chosen on the basis of drugs combinations effective in the palliative setting; platinum-based doublet plus etoposide or taxanes, or multiple drug regimens including anthracycles are the most used, no data favoring one regimen over the others. Response rates among 60 to 100% in main phase II trials are reported, with primary chemotherapy alone or plus concomitant radiotherapy, in all thymic malignancies. Higher response rates with anthracycles in thymoma and cisplatin in thymic carcinoma are suggested by literature evidence. Adjuvant; thymic carcinoma; stage

Recurrent sternal thymoma after thymectomy by video-assisted thoracic surgery

An 81-year-old man underwent thymectomy by video-assisted thoracic surgery for a mediastinal tumor. The pathological diagnosis was Masaoka stage II type B3 thymoma. Thirty-six months later, he presented with a growing mass on his anterior chest wall. Computed tomography showed a lobulated tumor in the sternum with bone destruction. Positron-emission tomography-computed tomography showed a maximal standardized uptake of 12.3 in the tumor. Core needle biopsy confirmed a metastatic sternal tumor from a type B3 thymoma. We partially resected the sternum and reconstructed the defect using an expanded polytetrafluoroethylene sheet. The patient has remained recurrence-free for 3 years after the second surgery.

World Health Organization type B2 thymoma with an abundance of Hassall's corpuscles: A case report.

Hassall's corpuscles (HCs) are characteristic components of the medulla of the mammalian thymus and thymoma with an abundance of HCs is even more rare, with only five cases having been reported in the literature, to the best of our knowledge. Furthermore, their morphology usually resembles World Health Organization (WHO) type B2 or B3 thymoma. The biological behavior appears indolent and is rarely associated with myasthenia gravis. However, whether it is a separate entity or a variant of organotypical thymoma WHO B2 or B3 remains to be elucidated. The present case report reports a type B2 thymoma with a large presence of HCs from a 58-year-old Chinese woman, and investigates its histopathological characteristics, immunological features and biological behavior. Notably, the present case appeared biologically more aggressive compared with the cases reported previously. The aim of describing this rare case of thymoma with an abundance of HCs is so that it can be recognized and classified by pathologists.

Giant thymoma successfully resected via median sternotomy and anterolateral thoracotomy: a case report

BackgroundSome patients with thymoma present with a very large mass in the thoracic cavity. Although the most effective treatment for thymoma is surgical resection, it is difficult to perform because of the size of the tumor and the infiltration of tumor into the surrounding organs and vessels. We report a patient with a giant thymoma that was completely resected via a median sternotomy and left anterolateral thoracotomy.Case presentationA 63-year-old woman presented with a mass in the left thoracic cavity that was incidentally found on a chest X-ray. Chest computed tomography revealed a giant mass (16 × 10 cm) touching the chest wall and diaphragm and pressed against the heart and left upper pulmonary lobe. Complete resection was performed via a median sternotomy and left anterolateral thoracotomy. The tumor was histologically diagnosed as a WHO type B2 thymoma, Masaoka stage II.ConclusionsGiant thymomas tend to grow expansively without invasion into surrounding organs and vessels. Surgical resection that employs an adequate approach must be considered, regardless of the size of the tumor.

An immunohistochemical panel consisting of EZH2, C-KIT, and CD205 is useful for distinguishing thymic squamous cell carcinoma from type B3 thymoma

Type B3 thymoma and thymic squamous cell carcinoma (SqCC) often cause a diagnostic problem due to their histological similarities. The aim of this study is to identify EZH2 as a novel and powerful biomarker that can effectively distinguish thymic SqCC from type B3 thymoma, and find optimal combinations among 11 markers. A total of 53 patients, comprising 26 with type B3 thymoma and 27 with thymic SqCC, were allocated to the discovery or validation cohorts, and immunohistochemical staining was performed and analyzed. The expression level of each marker was scored, and receiver-operator characteristic curve analysis was performed to evaluate their diagnostic accuracies. This analysis identified EZH2, C-KIT, and CD205 as useful markers for distinguishing thymic SqCC, and a combined panel approach using them further improved diagnostic accuracy in both the discovery and validation cohorts. In the combined cohorts analysis, EZH2 was the single best marker with 88.9% sensitivity and 100% specificity [area under the curve (AUC) = 0.967]. The sensitivity and specificity were 85.2% and 100% (AUC = 0.962) for C-KIT, and 100% and 73.1% (AUC = 0.844) for CD205. The combined panel had the highest sensitivity and specificity at 96.3% and 100%, which was significantly or marginally higher than those of EZH2, C-KIT, and CD205 alone (P = 0.071, 0.034, and 0.005, respectively). The present findings indicate that EZH2 is useful as a novel diagnostic marker for distinguishing thymic SqCC and that the panel approach can be used as an effective differential diagnostic tool in daily practice.

Correlation between the Expression of PD-L1 and Clinicopathological Features in Patients with Thymic Epithelial Tumors.

The incidence of thymic epithelial tumors (TETs) in the Chinese population was much higher than that in the North American population. In clinical treatment, the prognosis of benign tumors after surgical resection was significantly better than that of malignant tumors. Currently, the commonly used clinical indicators for TET staging included Masaoka staging and WHO (2015) pathological criteria; however, the distinction between the benign and malignant tumors and diagnosis is yet to be explored. The current study demonstrated that the expression of PD-L1 in tumor cells was correlated with the degree of TET malignancy. The quantitative analysis of PD-L1 expression in 70 cases of TET tumor samples revealed that the positive rate of PD-L1 expression in types A, AB, B1, and B2 of thymoma (40 cases) was 37.5% (15/40), which was significantly lower than that in type B3 thymoma and thymic carcinoma (76.67%, 30 cases, 23/30) as demonstrated by chi-square test (P < 0.05). In addition, the two methods were analyzed for the quantitative detection of PD-L1 expression. The results from the estimation of transcriptional RNA expression and quantitative protein immunohistochemistry were consistent (r = 0.745). Furthermore, we also analyzed PD-L1 expression level in different types of TETs from TCGA database and observed that higher PD-L1 expression was in thymic carcinoma than in thymoma. Therefore, it could be concluded that PD-L1 expression in TET cells was correlated with the degree of malignancy, whereas the estimation of PD-L1 expression was potentially applicable in the clinical staging of TETs.

Outcomes of Extended Thymectomy in Myasthenic and Non-Myasthenic Thymus Tumors

Aim: We retrospectively reviewed the results of patients who underwent extended thymectomy for thymic malignancy and planned to demonstrate the therapeutic effect of surgical treatment in patients with thymus tumors. Material and Method: The results of 29 patients with thymic malignancy who underwent consecutively expanded thymectomy between October 2012 and January 2018 in our clinic were examined in detail. Preoperative, postoperative and postoperative follow-up parameters of the cases were recorded. Results: 13 of the patients were male and 16 were female. The mean age was calculated as 41.4±17.7 (range 9–75 years). Nine of the cases (31%) were accompanied by myasthenia graves (MG) disease. Mean FEV1 was 2678.17±954.5 ml and mean FEV1 was calculated as 94±19.8 ml. Thymectomy was performed with sternotomy in 20 patients and thoracoscopic thymectomy was performed in 9 patients. The mean duration of operation was 137.9±31.8 minutes (133.1±45.5 minutes in thoracoscopy group, 134.1±26.5 minutes in sternotomy group), mean perioperative bleeding was 116.6±107 ml, postoperative drainage amount was 417.3±339.9 ml and duration of drainage was 2.6±0.89 days. Complication rate was found to be 13.7% while mortality was not observed. When the postoperative pain scores of the patients were evaluated, the first 24 hour visual analogue pain score (VAS) averaged 3.4, 24–48 hours 2.71 and 48–72 hours 1.9. Mean hospital stay was 4.3±2.5 days and mean follow-up was 34.7 months (1.5–124 months). Recurrence was developed only in one patient with type B2 thymoma and a myasthenic crisis was observed in one patient, on the 10th postoperative day. While no tumor metastasis was observed in any patient during the follow-up, the mean disease-free survival was 34.9 months. Conclusion: Extended thymectomy can be safely performed with low morbidity and mortality using transsternal or thoracoscopic approach in myasthenic and non-myasthenic thymus tumors.