The 2021 WHO Classification of Tumors of the Thymus and Mediastinum: What Is New in Thymic Epithelial, Germ Cell, and Mesenchymal Tumors?

Unraveling the complexities of immunotherapy for thymic epithelial tumors via bioinformatics and experimental analyses

INTRODUCTION

Thymic epithelial tumors (TETs) are rare neoplasms typically located in the anterior mediastinum. While immune checkpoint inhibitors (ICIs) show promise for advanced or refractory TETs, their clinical application is hindered by heterogeneous responses across TET subtypes, lack of reliable predictive markers, and the risk of immune-related adverse events (irAEs).

METHODS

We analyzed TCGA, GEO, and GTEx databases to identify differentially expressed genes (DEGs) among three TET subtypes. Comprehensive enrichment analysis determined gene functions and pathways. CIBERSORT analysis revealed subtype-specific immune infiltration profiles. We assessed immune-related genes using immune/stromal scores, TIDE scores, and immune checkpoint gene correlation analysis. Immunohistochemistry was performed to evaluate FGF17 and PD-L1 protein expression levels and their correlation in TET samples.

RESULTS

Our findings revealed distinctive molecular and immune infiltration patterns across TET subtypes. Pathway analysis showed upregulation of immune-related pathways in type C. CIBERSORT analysis revealed higher fractions of plasma cells and activated CD4 T cells in type C and increased resting dendritic cells in type A or B3. Furthermore, we identified 1,100 DEGs between responders and non-responders to pembrolizumab. FGF17 emerged as a potential predictive marker for immunotherapy response, showing significantly lower expression in type C and a strong negative correlation with PD-L1 expression (P < 0.001). We identified 115 genes potentially linked to irAEs, with CXCL8, IL17A, and CD40LG among the top hub genes in the protein-protein interaction network.

CONCLUSIONS

This study provides insights into subtype-specific molecular and immune characteristics of TETs, identifies FGF17 as a potential negative biomarker for immunotherapy response (with lower expression potentially indicating better response), and elucidates mechanisms of irAEs. These findings contribute to the development of targeted immunotherapeutic approaches for managing TETs, particularly in predicting response to immune checkpoint inhibitors.

Robotic-assisted extended thymectomy for large resectable thymoma: 21 years' experience

OBJECTIVE

This study aims to evaluate the perioperative and midterm oncological outcomes of robotic-assisted thoracic surgery extended thymectomy for patients with large resectable thymomas compared with small thymomas.

METHODS

This retrospective single-center study included 204 patients with thymomas who underwent robotic-assisted thoracic surgery extended thymectomy between January 2003 and February 2024. Patients were divided into 2 groups based on the thymoma size (5-cm threshold).

RESULTS

The study comprised 114 patients (55.9%) in the small thymoma group and 90 patients (44.1%) in the large thymoma group. No significant differences were found between the groups regarding gender, age, proportion of elderly patients, or pathologic high-risk classifications. Apart from a longer operative time (P = .009) in the large thymoma group, no differences were observed between the 2 groups regarding surgical parameters and postoperative outcomes. No deaths occurred within 30 days in either group. During a median follow-up of 61.0 months (95% CI, 48.96-73.04), 4 patients experienced recurrence (1.96%). No significant differences in the 5-year overall survival (P = .25) or recurrence-free survival (P = .43) were observed between groups.

CONCLUSIONS

Robotic-assisted thoracic surgery extended thymectomy is technically feasible, safe, and effective for treating large resectable thymomas. Moreover, midterm outcomes for patients with completely resected large thymomas were comparable to those with small thymomas during a median follow-up period of up to 5 years.

The Role of [18F]F-FDG PET/CT for Predicting Histology and Prognosis in Patients with Thymic Lesions

OBJECTIVES

To investigate whether 18F-fluorodeoxyglucose positron emission tomography-computed tomography ([18F]F-FDG PET/CT) metabolic parameters were associated with histology and to assess their prognostic role in patients with thymic lesions.

PATIENTS AND METHODS

In total, 116 patients (49/67 M/F; mean age 59.5 years) who underwent preoperative [18F]F-FDG PET/CT and thymectomy from 2012 to 2022 were retrospectively analyzed. Associations between histology and metabolic parameters (maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), peak standardized uptake value (SUVpeak), total lesion glycolysis (TLG), metabolic tumor volume (MTV), ratio between target lesion and liver SUVmax (rPET), quotient of SUVpeak in the tumor residual and SUVmean in a 20-cm3 volume of interest (qPET), and tumor-to-mediastinum (T/M) were analyzed. Freedom from recurrence (FFR) was determined and compared using the Kaplan-Meier and the log-rank test. The median follow-up was 38 months (range 14-72 months).

RESULTS

In total, 27 thymic hyperplasia, 41 low-risk thymomas (LRT) (types A, AB, and B1), and 48 high-risk thymomas (HRT) (B2, B3 thymoma, and carcinoma) were included. SUVmax, SUVmean, SUVpeak, rPET, qPET, and T/M were significantly higher in HRT than LRT and hyperplasia (p < 0.001). TLG and MTV were significantly higher in patients with LRT (p < 0.001). Only rPET, qPET, and T/M remained significantly higher in HRT than in LRT subgroups (p = 0.042, p = 0.049, and p = 0.028, respectively). SUVmax, SUVmean, and SUVpeak cutoffs of < 4.3, < 2.87, and 4.03, respectively, significantly distinguished patients with longer FFR (p = 0.009, p = 0.05, and p = 0.05).

CONCLUSIONS

Positron emission tomography (PET) metabolic parameters could help to differentiate thymic histotypes. Standardized uptake value (SUV)-based parameters appear promising to predict recurrent disease.

Metastatic Thymic Mucoepidermoid Carcinoma: The Diagnostic Challenges and Role of CRTC1/MAML2 Translocation in Accurate Diagnosis and Treatment

Mucoepidermoid carcinoma (MEC) is a subtype of epithelial neoplasms commonly found in salivary glands, but can also be seen in the thymus. Diagnosing MEC of the thymus is sometimes challenging due to its histological similarities with adenosquamous carcinoma (ASC). This case report describes a 64-year-old female with a history of metastatic endometrial adenocarcinoma who presented to an oncology clinic with a thymic mass as well as multiple mass lesions in the liver, bone, and abdominal wall. Initially diagnosed as thymic ASC based on histopathology, further genomic profiling revealed a CRTC1/MAML2 translocation, leading to the diagnosis of metastatic MEC of the thymus. Comprehensive genomic testing played a crucial role in distinguishing MEC from ASC. This case highlights the importance of genetic testing in cases of uncertain primary origins and in differentiating between morphologically similar tumors.

When the heart and tumours intertwine: pulmonary hypertension associated with a neuroendocrine tumour-a case report

Background

Pulmonary hypertension caused by extrinsic pulmonary vascular compression secondary to mediastinal neuroendocrine tumours is a very rare condition, posing a diagnostic challenge. There is no clear consensus regarding the best treatment strategy due to the lack of clinical data, leading to poor prognoses for these patients.

Case summary

We present the case of a 38-year-old man hospitalized with signs of pulmonary hypertension and acute heart failure. He had experienced progressive dyspnoea over the 12 months prior to admission. Studies performed at our institution revealed dilation of the right heart chambers with right ventricular systolic dysfunction and pulmonary hypertension. Cardiac tomography showed extrinsic vascular compression, leading to emergency endovascular treatment for superior vena cava syndrome, followed by stent implantation in the pulmonary arteries and innominate vein. Further studies identified a mediastinal neuroendocrine tumour, for which chemotherapy was initiated, without clinical response. During outpatient follow-up, cardiac function worsened, and the patient died 48 months after symptoms onset due to a lung infection.

Discussion

Pulmonary hypertension secondary to extrinsic vascular compression by mediastinal tumour is a rare condition that presents a diagnostic challenge. This case highlights the importance of considering oncological aetiology in patients with progressive dyspnoea and pulmonary vascular extrinsic compression. Despite early treatment, the prognosis for these patients remains poor.

SNAI1 promotes epithelial-mesenchymal transition and maintains cancer stem cell-like properties in thymic epithelial tumors through the PIK3R2/p-EphA2 Axis

BACKGROUND

Thymic epithelial tumors (TETs) are infrequent malignancies that arise from the anterior mediastinum. Therapeutic options for TETs, especially thymic carcinoma (TC), remain relatively constrained. This study aims to investigate the oncogenic hub gene and its underlying mechanisms in TETs, as well as to identify potential therapeutic targets.

METHODS

Weighted gene co-expression network analysis (WGCNA) and differential gene expression (DEG) analysis were utilized to identify significant oncogenes using The Cancer Genome Atlas (TCGA) database. LASSO logistic regression analysis was performed to assess the association between hub genes and clinical parameters. The influence of the hub gene on promoting epithelial-mesenchymal transition (EMT), tumor progression, and regulating cancer stem cell-like properties was assessed both in vitro and in vivo. Single-cell RNA sequencing (scRNA-seq) was utilized to analyze the alterations in the tumor and its microenvironment following the administration of the hub gene's inhibitor. Multiplex immunohistochemistry (mIHC) was employed to validate the results. The potential mechanism was further elucidated through the utilization of Cleavage Under Targets and Tagmentation (CUT&Tag), RNA-sequencing, chromatin immunoprecipitation (ChIP), CUT&RUN, luciferase reporter assay, co-immunoprecipitation (Co-IP), mass spectrometry (MS) and phosphoproteomic assays.

RESULTS

SNAI1 was identified as a hub transcription factor for TETs, and its positive correlation with the invasiveness of the disease was confirmed. Subsequent experiments revealed that the upregulation of SNAI1 augmented the migration, invasion, and EMT of TET cell lines. Furthermore, we observed that the overexpression of SNAI1 sustained cancer stem cell-like properties. ScRNA-seq demonstrated that the use of a SNAI1 inhibitor inhibited the transition of macrophages from M1 to M2 phenotype, a finding further validated by multiplex immunohistochemistry (mIHC). Phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2) was identified as one of the downstream targets of SNAI1 through CUT&Tag and RNA-sequencing, a finding validated by ChIP-qPCR, CUT&RUN-qPCR, luciferase reporter and immunofluorescence assays. Co-IP, MS and phosphoproteomic assays further confirmed that PIK3R2 directly interacted with phosphorylated EphA2 (p-EphA2), facilitating downstream GSK3β/β-catenin signaling pathway.

CONCLUSION

The tumorigenic role of SNAI1 through the PIK3R2/p-EphA2 axis was preliminarily validated in TETs. A potential therapeutic strategy for TETs may involve the inhibition of SNAI1.

Weakly supervised learning in thymoma histopathology classification: an interpretable approach

Introduction

Thymoma classification is challenging due to its diverse morphology. Accurate classification is crucial for diagnosis, but current methods often struggle with complex tumor subtypes. This study presents an AI-assisted diagnostic model that combines weakly supervised learning with a divide-and-conquer multi-instance learning (MIL) approach to improve classification accuracy and interpretability.

Methods

We applied the model to 222 thymoma slides, simplifying the five-class classification into binary and ternary steps. The model features an attention-based mechanism that generates heatmaps, enabling visual interpretation of decisions. These heatmaps align with clinically validated morphological differences between thymoma subtypes. Additionally, we embedded domain-specific pathological knowledge into the interpretability framework.

Results

The model achieved a classification AUC of 0.9172. The generated heatmaps accurately reflected the morphological distinctions among thymoma subtypes, as confirmed by pathologists. The model's transparency allows pathologists to visually verify AI decisions, enhancing diagnostic reliability.

Discussion

This model offers a significant advancement in thymoma classification, combining high accuracy with interpretability. By integrating weakly supervised learning, MIL, and attention mechanisms, it provides an interpretable AI framework that is applicable in clinical settings. The model reduces the diagnostic burden on pathologists and has the potential to improve patient outcomes by making AI tools more transparent and clinically relevant.

DNA methylation as a new tool for the differential diagnosis between T-LBL and lymphocyte-rich thymoma

T-lymphoblastic lymphoma (T-LBL) and thymoma are two rare primary tumors of the thymus deriving either from T-cell precursors or from thymic epithelial cells, respectively. Some thymoma subtypes (AB, B1, and B2) display numerous reactive terminal deoxynucleotidyl transferase-positive (TdT+) T-cell precursors masking epithelial tumor cells. Therefore, the differential diagnosis between T-LBL and TdT+ T-lymphocyte-rich thymoma could be challenging, especially in the case of needle biopsy. To distinguish between T-LBL and thymoma-associated lymphoid proliferations, we analyzed the global DNA methylation using two different technologies, namely MeDIP array and EPIC array, in independent samples series [17 T-LBLs compared with one TdT+ lymphocyte-rich thymoma (B1 subtype) and three normal thymi, and seven lymphocyte-rich thymomas compared with 24 T-LBLs, respectively]. In unsupervised principal component analysis (PCA), T-LBL and thymoma samples clustered separately. We identified differentially methylated regions (DMRs) using MeDIP-array and EPIC-array datasets and nine overlapping genes between the two datasets considering the top 100 DMRs including ZIC1, TSHZ2, CDC42BPB, RBM24, C10orf53, and MACROD2. In order to explore the DNA methylation profiles in larger series, we defined a classifier based on these six differentially methylated gene promoters, developed an MS-MLPA assay, and demonstrated a significant differential methylation between thymomas (hypomethylated; n = 48) and T-LBLs (hypermethylated; n = 54) (methylation ratio median 0.03 versus 0.66, respectively; p < 0.0001), with MACROD2 methylation status the most discriminating. Using a machine learning strategy, we built a prediction model trained with the EPIC-array dataset and defined a cumulative score taking into account the weight of each feature. A score above or equal to 0.4 was predictive of T-LBL and conversely. Applied to the MS-MLPA dataset, this prediction model accurately predicted diagnoses of T-LBL and thymoma. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

DNA methylation analysis of multiple genes in thymic epithelial tumors

Aim: To investigate DNA methylation levels of a panel of genes in thymic epithelial tumors (TETs).Materials & methods: We selected 15 genes among the most promising epigenetic biomarkers of TETs and evaluated their methylation levels in 71 TET samples.Results: thymic carcinomas (TCs) showed hypermethylation of GHSR and ELF3 genes and reduced IL1RN methylation levels compared with thymomas (TMs) and healthy thymic tissues. RAG1 was hypomethylated in TMs compared with healthy thymic tissues. No difference in the methylation levels of the investigated genes was seen among TM stages and subtypes. No changes in blood methylation levels of the investigated genes were seen among TET subtypes.Conclusion: The present study confirms GHSR, ELF3, IL1RN and RAG1 as TET epigenetic biomarkers.

Hepatoid thymic carcinoma in a polycythemia vera patient treated with ropeginterferon Alfa-2b: Clinical, histopathological and molecular correlates

Hepatoid thymic carcinoma (HTC) is an extremely rare variant of primary epithelial tumor of the thymus morphologically resembling hepatocellular carcinoma Herein, we report an additional case of HTC diagnosed in a 40-years-old man affected by polycythemia vera and treated with ropeginterferon alfa 2-b, for the first time deeply analyzing the molecular profile of this distinctive thymic malignancy. By immunohistochemistry, tumor cells were positive for cytokeratin 7-19, GLUT1, and Hep-Par-1, whereas AFP tested negative. Whole exome sequencing revealed loss of function mutations in TP53, STK11, PBRM1, SMAD3, FN1, NTRK1, and FANCD2, as well as gain of function mutations in MTOR, BCL11A and COL1A1, along with amplification of CCND3 and MDM2. This mutational landscape halfway between thymic carcinoma (TP53, PBRM1) and hepatoid variant carcinoma of other sites (STK11) suggests that, at some point during carcinogenesis, a switch occurred from an epithelial thymic phenotype to a hepatoid-like one.

"Mini Brain" Appearance in Spinal Metastasis From Type A Thymoma Detected by 18F-FDG PET/CT

ABSTRACT

A 66-year-old man presented with persistent dull pain in the lower back for over 7 months. An expansile lytic lesion in the L4 vertebral body showed a characteristic "mini brain" appearance on MRI, which is highly suggestive of plasmacytoma. 18F-FDG PET/CT scan revealed increased FDG uptake in the L4 lesion, with an additional finding of a mass in the anterior mediastinum that showed mild FDG uptake. Lumbar surgery and complete resection of the anterior mediastinum tumor confirmed spinal metastatic type A thymoma, which was classified as p-T1aN0M1b, stage IVb. The patient's condition improved postsurgery and chemotherapy, with long-term follow-up necessary due to recurrence risk.

Minimally Invasive Sampling of Mediastinal Lesions

This narrative review examines the existing literature on minimally invasive image-guided sampling techniques of mediastinal lesions gathered from international databases (Medline, PubMed, Scopus, and Google Scholar). Original studies, systematic reviews with meta-analyses, randomized controlled trials, and case reports published between January 2009 and November 2023 were included. Four authors independently conducted the search to minimize bias, removed duplicates, and selected and evaluated the studies. The review focuses on the recent advancements in mediastinal sampling techniques, including EBUS-TBNA, EUS-FNA and FNB, IFB, and nodal cryobiopsy. The review highlights the advantages of an integrated approach using these techniques for diagnosing and staging mediastinal diseases, which, when used competently, significantly increase diagnostic yield and accuracy.

Robotic-assisted versus video-assisted thoracoscopic surgery for thymic epithelial tumours, from the European Society of Thoracic Surgeons Database

OBJECTIVES

Minimally invasive thymectomy is an accepted approach for early-stage thymic epithelial neoplasia, reducing pain and length of stay compared with open surgery. In this study, we compare robotic and video-assisted thymectomy to assess pathological resection status, overall and disease-free survival.

METHODS

Data were retrieved from the European Society of Thoracic Surgeons prospectively maintained thymic database. Eighty-two international centres were invited to participate in the ESTS registry. Thirty-seven centres agreed to take part. We included all patients who had undergone complete thymectomy for malignancy through a minimally invasive approach and excluded patients in whom complete data were not available.

RESULTS

Between October 2001 and May 2021, a total of 899 patients with thymic malignancy underwent minimal access surgical resection and were included in the study. A propensity matched analysis was conducted with interrogation of 732 patients. Median age was 55 years, and 408 (56%) patients were female. Propensity matched was performed with 1:1 matching for surgical approach (video assisted = 366, robot assisted = 366). Robot-assisted surgery conferred significantly lower odds of incomplete resection (R1; 0.203 95% CI 0.13-0.317; P < 0.001). However, there was no difference in terms of overall and disease-free survival between the 2 techniques.

CONCLUSIONS

In this analysis, after adjusting for thymoma stage, the odds of incomplete surgical resection were higher in patients undergoing video-assisted surgery than robotic. However, there was no difference in overall or disease-free survival. With data maturation and increased follow-up, this would need repeat analysis and perhaps may provide more credence to the concept of a prospective randomized study to compare outcomes in thymic epithelial neoplasia by surgical approach with a standardized pathological work-up.

Single-cell sequencing has revealed a more complex array of thymic epithelial cells

Thymic epithelial cells participate in the maturation and selection of T lymphocytes. This review explores recent insights from single-cell sequencing regarding classifying thymic epithelial cells in both normal and neoplastic thymus. Cortical thymic epithelial cells facilitate thymocyte differentiation and contribute to positive selection. Medullary epithelial cells are distinguished by their expression of AIRE. Cells progress from a pre-AIRE state, containing precursors with cortical and medullary characteristics, termed junctional cells. Mature medullary epithelial cells exhibit promiscuous gene expression and after that downregulate AIRE mRNA. Post-AIRE cells can adopt a Hassall corpuscle-like phenotype or exhibit distinctive differentiation characteristics including tuft cells, ionocytes, neuroendocrine cells, and myoid cells.

A predictive model of computed tomography and clinical features of EGFR gene mutation in lung adenocarcinoma

Purpose: This study aims to develop a predictive model for epidermal growth factor receptor (EGFR) mutations in lung adenocarcinoma by integrating computed tomography (CT) imaging features with clinical characteristics. Methods: A retrospective analysis was conducted using electronic medical records from 194 patients diagnosed with lung adenocarcinoma between January 2016 and December 2020, with approval from the institutional review board. Features were selected using LASSO regression, and predictive models were built using logistic regression, support vector machine, and random forest methods. Individual models were created for clinical features, CT imaging features, and a combined model to predict EGFR mutations. Results: The training set revealed that alcohol consumption, intrapulmonary metastasis, and pleural effusion were statistically significant in distinguishing between wild-type and mutation groups (p < 0.05). In the testing set, hilar and mediastinal lymphadenopathy showed statistical significance (p < 0.05). The combined model outperformed the individual clinical and CT imaging feature models. In the testing set, the logistic regression model achieved the highest AUC of 0.827, with sensitivity, specificity, and accuracy of 0.714, 0.712, and 0.712, respectively. Nomogram analysis identified lobulation as an important feature, with a predicted probability of up to 0.9. The decision curve analysis showed that the CT imaging feature model provided a higher net benefit compared to both the clinical feature model and the combined model. Conclusion: In summary, while the combined model outperformed the individual feature models in the testing set, the CT imaging feature model demonstrated the greatest clinical net benefit. Lobulation was identified as an important predictor of EGFR mutations in lung adenocarcinoma.

Association between Infection and Calculated Globulin Level among Patients with Thymic Epithelial Tumor

Background: Thymic epithelial tumors (TETs) are uncommon malignancies uniquely associated with autoimmunity and immunodeficiency. Previous studies among patients with primary immunodeficiency diseases have shown that a low calculated globulin (CG) level, obtained by subtracting albumin from total protein level, is associated with infection risk. We investigated this association among patients with TET. Methods: A cross-sectional retrospective study was performed based on electronic medical records of patients with TET treated during 2002-2024 at a tertiary care institution. For each patient, their lowest CG level and the date of occurrence were identified. The incidence of serious infection requiring hospitalization during 6 months before and 6 months after the index date was recorded. Multivariable Poisson regression models were constructed. Results: Among 101 TET patients, 96 patients (95%) had the information available to derive at least one CG level. The median lowest CG level was 2.65 g/dL (range 1.0-4.2). There were 33 serious infection episodes. Pneumonia was the most prevalent type of infection in 52% of episodes. In a multivariable analysis, a CG level below 2.0 was independently associated with the prevalence of infection with a prevalence ratio of 6.18 (95% CI: 3.12-12.23, p < 0.001). Furthermore, thymectomy was significantly associated with infection. Conclusions: Among patients with TET, a low CG level was associated with an increased prevalence of serious infections. Our limited experiences suggest that it is feasible to derive the CG level for most patients during routine clinical care.

Identification of zinc finger MIZ-type containing 2 as an oncoprotein enhancing NAD-dependent protein deacetylase sirtuin-1 deacetylase activity to regulate Wnt and Hippo pathways in non-small-cell lung cancer

BACKGROUND

Zinc finger MIZ-type containing 2 (ZMIZ2) can function as a coactivator and participate in the progression of certain malignant tumors; however, its expression and underlying molecular mechanism in non-small-cell lung cancer (NSCLC) remains unknown. In this study, we aim to analyze the expression of ZMIZ2 and its tumorigenic function in NSCLC, identifying its related factors.

METHODS

ZMIZ2 expression in NSCLC tissue samples and cell lines was examined using immunohistochemistry and western blotting; its biological role was investigated using in vivo and in vitro assays. The association between ZMIZ2 and NAD-dependent protein deacetylase sirtuin-1 (SIRT1) was demonstrated using mass spectrometry and immunoprecipitation experiments. Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG)-based enrichment analysis, luciferase reporter assay, and real-time quantitative polymerase chain reaction (RT-qPCR) were conducted to verify the impact of ZMIZ2-SIRT1 combination on Hippo/Wnt pathways.

RESULTS

ZMIZ2 was highly expressed in NSCLC and positively associated with advanced pTNM staging, lymph node metastasis, and poor overall survival. Functional experiments revealed that ZMIZ2 promotes the proliferation, migration, and invasiveness of lung cancer cells-establishing its role as a promoter of oncogenes. Molecular mechanism studies identified SIRT1 as an assisted key factor interacting with ZMIZ2. KEGG enrichment analysis revealed that ZMIZ2 is closely related to Wnt/Hippo pathways; ZMIZ2-SIRT1 interaction enhanced SIRT1 deacetylase activity. Direct downregulation of intranuclear β-catenin and yes-associated protein (YAP) acetylation levels occurred independently of upstream proteins in Wnt/Hippo pathways; transcriptional activities of β-catenin-transcription factor 4 (TCF4) and YAP-TEA domain family transcription factors (TEADs) were amplified.

CONCLUSIONS

ZMIZ2 promotes the malignant phenotype of lung cancer by regulating Wnt/Hippo pathways through SIRT1, providing an experimental basis for discovering novel biomarkers and developing tumor-targeted drugs.

Evolving treatment landscape in thymic epithelial tumors: From mechanism to therapy

Thymic epithelial tumors (TETs) are rare neoplasms of the anterior mediastinum that arise from thymic epithelial cells. Although surgery is the preferred treatment for resectable TETs, the options for unresectable or recurrent advanced-stage TETs are limited beyond platinum-based chemotherapy. The evolving landscape of TET treatments is marked by significant advancements in targeted therapies and immunotherapies, particularly with anti-angiogenic agents and immune checkpoint inhibitors (ICIs). While monotherapies demonstrated certain efficacy, the development of combination strategies is vital for improving patient outcomes. This review consolidates progress in anti-angiogenic therapies and ICIs, emphasizing the evolution of combination therapies of TETs. Furtherly, we particularly discuss new first-line strategies based on these advancements and emphasizes exploring novel treatments like antibody-drug conjugates, immunomodulatory drugs and cytokine-based agents for TETs. Mechanistically, the molecular features of TETs integrated with clinical diagnosis and targeted therapy, and immunophenotyping of TETs along with its impact on the efficacy and safety of immunotherapy are discussed. Thus, this review systemizes the development in the treatment landscape of TETs, integrating the corresponding molecular and immune mechanisms, aiming to provide new references for the treatment of TETs.

Thymic epithelial tumor medical treatment: A narrative review

Thymic epithelial tumors, a malignancy originating in the thymus, are the commonest primary neoplasm of the anterior mediastinum; however, among thoracic tumors, they have a relatively low incidence rare. Thymic epithelial tumors can be broadly classified into thymic carcinoma and thymoma. As the cornerstone of thymic tumor treatment, surgery is the preferred treatment for early-stage patients, whereas, for advanced unresectable thymic tumors, the treatment is chemoradiotherapy. Targeted therapy is less effective for thymic tumors. Moreover, the use of immune checkpoint inhibitors as another effective treatment option for advanced unresectable thymic tumors, particularly thymomas, is limited owing to immune-related adverse effects. Here, we have summarized all pertinent information regarding chemotherapy, especially preoperative neoadjuvant chemotherapy, and chemotherapy in combination with other treatments, and reviewed the effectiveness of these procedures and recent advances in targeted therapy. In addition, we analyzed the efficacy and safety of immune checkpoint inhibitors in thymic epithelial tumors, to provide a holistic treatment view.

Pre-thymectomy disease severity predicts outcome in acetylcholine receptor antibody-positive generalised myasthenia gravis

INTRODUCTION

There are only a few studies exploring post-thymectomy outcome in patients with acetylcholine receptor antibody (AChR-Ab)-positive generalised myasthenia gravis (MG).

OBJECTIVE

To assess the predictors of outcome in patients with AChR-Ab-positive generalised MG who underwent thymectomy.

METHODS

A retrospective study of 53 patients from a single neuroscience centre in the UK.

RESULTS

The mean disease duration from diagnosis was 6.2 ± 4.3 years. Pre-thymectomy, 37 patients had mild weakness affecting muscles other than ocular muscles, 11 patients had moderate weakness and 5 patients had severe weakness. 27/53 patients had thymoma. Post-thymectomy (mean duration of 5.7 ± 4.2 years), 34 patients (64%) had a good outcome characterised by Myasthenia Gravis Foundation of America Post-Intervention Status of complete stable remission (no symptoms or signs of MG for at least 1 year without any therapy) or pharmacological remission (no symptoms or signs of MG with some form of therapy) or minimal manifestations (no symptoms of functional limitations from MG but weakness on examination of some muscles with or without some form of therapy) on last follow-up visit. Having thymomatous or non-thymomatous MG did not predict the outcome. The only variable that did predict outcome was pre-thymectomy disease severity; patients with mild weakness before thymectomy had a favourable outcome. We found an accuracy of 83% predicting outcome (95% confidence interval (CI) 60%, 100%) with a sensitivity of 84% (95% CI 68%, 94%) and specificity of 81% (95% CI 54%, 96%).

CONCLUSION

Disease severity before thymectomy predicts outcome in patients with AChR-Ab-positive generalised MG.

Depiction of the Genetic Alterations and Molecular Landscapes of Thymic Epithelial Tumors: A Systematic Review and Meta-Analysis

Thymic epithelial tumors (TETs), consisting of thymomas, thymic carcinomas (TCs), and thymic neuroendocrine tumors, are rare diseases. Surgery remains the prime option in resectable and early-stage TETs, while chemotherapy, targeted therapy, and immunotherapy are also potential treatment modalities. However, the inadequate comprehension of the molecular landscape of TETs impedes the exploitation of such therapies. Hence, we conducted a meta-analysis which includes 21 studies reporting on genomic alterations in TETs and 14 studies reporting on PD-L1 expression levels, respectively. The pooled estimated rates of the most frequently mutated genes and PD-L1 expression levels were analyzed using the R software. We uncovered that the pooled estimated overall mutation rate is 0.65 ([0.49; 0.81]), and the top three genes with highest mutation frequency in thymomas and TCs are GTF2I (0.4263 [0.3590; 0.4936]), TP53 (0.1101 [0.0000; 0.2586]), and RAS (0.0341 [0.0104; 0.0710]), and TP53 (0.1797 [0.0732; 0.3203]), CDKN2A (0.0608 [0.0139; 0.1378]), and TET2 (0.0318 [0.0087; 0.0639]), respectively. A uniform GTF2I mutational rate in thymomas and TP53 mutational rate in thymic squamous cell carcinomas (TSCCs) are also observed. The pooled estimated expression level of PD-L1 is 0.71 ([0.59-0.81]). This systematic review provides an overview of the gene alteration landscape and PD-L1 expression levels in TETs, discovers several potential confounding factors that may contribute to the high heterogeneity, and facilitates deeper investigations into the elucidation of the molecular landscape of TETs.

Practical methods to differentiate thymic malignancies by positron-emission tomography and tumor markers

PURPOSE

An accurate diagnosis of thymic malignancies is important, but challenging due to the broad range of differential diagnoses. This study aims to evaluate the efficacy of PET/CT and tumor markers for diagnosing thymic malignancies.

METHODS

Patients admitted to our department between January 2012 and December 2021 with primary anterior mediastinal tumors were retrospectively evaluated. We evaluated the relationship between the maximum standardized uptake value (SUVmax), tumor markers, and pathological diagnosis in four groups: thymic carcinoma, thymoma, lymphoma, and others.

RESULTS

In total, 139 patients were included in this study. The SUVmax was significantly higher in lymphoma, thymic carcinoma, and thymoma, in that order. The cytokeratin 19 fragment (CYFRA 21-1) was significantly higher in thymic carcinoma than in the other groups. An ROC curve analysis indicated that the optimal cut-off values of SUVmax for thymic carcinoma plus lymphoma and CYFRA 21-1 for thymic carcinoma were 7.97 (AUC = 0.934) and 2.95 (AUC = 0.768), respectively. Using a combination of cut-off values (SUVmax = 8, CYFRA 21-1 = 3), the accuracy rate for diagnosing thymic carcinoma was 91.4%.

CONCLUSIONS

The SUVmax and CYFRA 21-1 levels are significant indicators for the diagnosis of thymic carcinoma. Combining these indicators resulted in a more accurate diagnosis of thymic malignancies, which could facilitate the decision-making process for determining the optimal treatment strategies.

Case report: Potential role of immunotherapy in thymic malignancies: a unique case of a durable and complete response upon an immune checkpoint inhibitor

Thymic epithelial tumors are rare malignancies with an incidence of 1.7 cases per million people per year. They pose significant management challenges due to their association with autoimmune disorders. In this case report, we present the 21-year history of a patient diagnosed with advanced B2/B3 thymoma and Good's syndrome. The patient achieved a complete and durable response after receiving only two cycles of the immune checkpoint inhibitor Nivolumab. However, this positive outcome was accompanied by the development of severe immune-related myocarditis complicated by reactivation of cytomegalovirus. Moreover, the patient developed a highly uncommon subdiaphragmatic pararectal dissemination of the thymic tumor, which is a condition rarely described in the literature. Despite the success in achieving complete and durable response with immune checkpoint inhibitors, the emergence of immune-related adverse events highlights the potential challenges associated with these treatments, emphasizing the need for careful monitoring and a comprehensive understanding of the intricate interplay between cancer, immune system dysregulations and immunotherapy.

Histomorphological Spectrum and Diagnostic Challenges in Thymic Epithelial Neoplasms with their Prognostic Significance: A Case Series of 33 Cases at a Regional Cancer Center in Western India

Jahnavi Gandhi, DCPObjective  Pathological diagnosis of thymic epithelial neoplasms is challenging due to multiple subtypes, tumor heterogeneity, and variations in inter-observer reproducibility. Very few studies are available on their spectrum in the Indian subcontinent. In this study, we aimed to explore the morphological spectrum and diagnostic difficulties in the classification and subtyping of thymic epithelial neoplasms along with their prognostic significance in the Indian population. Material and Methods  Retrospectively, all surgically resected thymectomy specimens operated at our institute as well as outside review cases during the period were included. Histomorphology and immunohistochemistry (IHC) slides were reviewed and correlated with clinicopathological variables. Statistical Analysis  Microsoft Excel 2019 and SPSS version 20 were used for data analysis. Results  Among the 33 thymic epithelial neoplasms operated during the study period, the commonest subtype was thymoma B2 type followed by AB, B1, A, and B3 types. A single case each of micronodular thymoma, microscopic thymoma, and thymic carcinoma were identified. Six cases of thymomas with more than one pattern (other than 'A') were noted. The male:female ratio was 2:1. Stage I in Modified Masaoka staging and pT1a in TNM staging were most common. Seven cases had metastasis, four during initial presentation and three during subsequent follow-up. Discussion and Conclusion  Thymic epithelial neoplasms show morphological overlapping of features. Thorough sampling, morphology, and IHC for exact subtyping of thymoma and diligent search and documenting of lymphovascular invasion (LVI) are vital as both are separate risk factors for metastasis/recurrence and help the clinician in a better follow-up of patients.

Serum biomarkers of inflammation and vascular damage upon SARS-Cov-2 mRNA vaccine in patients with thymic epithelial tumors

OBJECTIVES

Thymic epithelial tumors (TET) patients are at high risk of autoimmune and hypoimmune complications. Limited evidence is available on the potential risk of immune-related and inflammatory reactions induced by SARS-Cov-2 vaccine in this patient population.

METHODS

In order to identify subjects at higher risk for vaccine complications, we prospectively evaluated a panel of serum biomarkers related to inflammation (TNF-α, IL-1β, -6, -10, -12, and -17A, IFN-α, β and γ, MPO, MMP-9), and vascular damage (E- and P-selectin, VEGF-A, P-ANCA and MCP-1) in 44 TET patients and in 30 healthy controls along the whole SARS-Cov-2 vaccine cycle.

RESULTS

About 50 % of subjects (either TET and controls) showed an increase of serum biochemical markers of inflammation and endothelial damage with a large heterogeneity of values. Such increase appeared early, after the first dose in control subjects and later, after the second dose in TET patients (in which we observed mainly an increase of inflammatory biomarkers). The values normalized after about 3 months and did not increase after the third, booster dose. No autoimmune or vascular complications were observed in the study subjects and no difference was observed in terms of vaccine response among subjects showing serum biomarkers increase and those who experienced no changes.

CONCLUSIONS

Our data highlight the relevance of Sars-Cov-2 vaccine in TET patients, as it resulted safe and prevented severe COVID-19. However, further studies are awaited to explore the mechanisms and the potential consequences of the observed increase of serum inflammatory and vascular damage biomarkers.

Immunotherapy in thymic epithelial tumors: tissue predictive biomarkers for immune checkpoint inhibitors

Thymic epithelial tumors (TETs) are rare malignant neoplasms arising in the thymus gland. Nevertheless, TETs, including thymomas (TMs), thymic carcinomas (TCs), and thymic neuroendocrine neoplasms (TNENs), are the most common mediastinal malignancies overall. A multidisciplinary approach is required for the appropriate diagnostic and therapeutic management of TETs. To date, the main therapeutic strategies are largely depended on the stage of the tumor and they include surgery with or without neoadjuvant or adjuvant therapy, represented by platinum-based chemotherapy, radiotherapy or chemoradiotherapy. Immune checkpoint inhibitors (ICIs) are ongoing under evaluation in the advanced or metastatic diseases despite the challenges related to the very low tumor mutation burden (TMB) and the high incidence of immune-related adverse events in TETs. In this regard, predictive impact of tissue biomarkers expression such as programmed cell death ligand-1 (PD-L1), and other emerging biomarkers, as well as their optimal and shared interpretation are currently under evaluation in order to predict response rates to ICIs in TETs.

Identification of cytokines in benign and malignant thymus tumors: based on Mendelian randomization and proteomics

Objective

The aim of this study was to identify potential causal cytokines in thymic malignancies and benign tumors from the FinnGen database using Mendelian randomization (MR).

Methods

In this study, data from genome-wide association studies (GWAS) of 91 cytokines were used as exposure factors, and those of thymic malignant tumors and thymic benign tumors were the outcome variables. Two methods were used to determine the causal relationship between exposure factors and outcome variables: inverse variance weighting (IVW) and MR-Egger regression. Sensitivity analysis was performed using three methods, namely, the heterogeneity test, the pleiotropy test, and the leave-one-out test.

Results

There was a causal relationship between the expression of fibroblast growth factor 5, which is a risk factor for thymic malignant tumors, and thymic malignant tumors. C-C motif chemokine 19 expression, T-cell surface glycoprotein CD5 levels, and interleukin-12 subunit beta levels were causally related to thymic malignant tumors and were protective. Adenosine deaminase levels, interleukin-10 receptor subunit beta expression, tumor necrosis factor (TNF)-related apoptosis-inducing ligand levels, and TNF-related activation-induced cytokine levels showed a causal relationship with thymic benign tumors, which are its risk factors. Caspase 8 levels, C-C motif chemokine 28 levels, interleukin-12 subunit beta levels, latency-associated peptide transforming growth factor beta 1 levels, and programmed cell death 1 ligand 1 expression showed a causal relationship with thymic benign tumors, which are protective factors. Sensitivity analysis showed no heterogeneity.

Conclusion

Cytokines showed a causal relationship with benign and malignant thymic tumors. Interleukin-12 subunit beta is a common cytokine that affects malignant and benign thymic tumors.

Use of CT-derived radiomic features to preoperatively identify invasive mucinous adenocarcinoma in solitary pulmonary nodules ≤3 cm

Objective

In this study, we aimed to utilize computed tomography (CT)-derived radiomics and various machine learning approaches to differentiate between invasive mucinous adenocarcinoma (IMA) and invasive non-mucinous adenocarcinoma (INMA) preoperatively in solitary pulmonary nodules (SPN) ≤3 cm.

Methods

A total of 538 patients with SPNs measuring ≤3 cm were enrolled, categorized into either the IMA group (n = 50) or INMA group (n = 488) based on postoperative pathology. Radiomic features were extracted from non-contrast-enhanced CT scans and identified using the least absolute shrinkage and selection operator (LASSO) algorithm. In constructing radiomics-based models, logistic regression, support vector machines, classification and regression trees, and k-nearest neighbors were employed. Additionally, a clinical model was developed, focusing on CT radiological features. Subsequently, this clinical model was integrated with the most effective radiomic model to create a combined model. Performance assessments of these models were conducted, utilizing metrics such as the area under the receiver operating characteristic curve (AUC), DeLong's test, net reclassification index (NRI), and integrated discrimination improvement (IDI).

Results

The support vector machine approach showed superior predictive efficiency, with AUCs of 0.829 and 0.846 in the training and test cohorts, respectively. The clinical model had AUCs of 0.760 and 0.777 in the corresponding cohorts. The combined model had AUCs of 0.847 and 0.857 in the corresponding cohorts. Furthermore, compared to the radiomic model, the combined model significantly improved performance in both the training (DeLong test P = 0.045, NRI 0.206, IDI 0.024) and test cohorts (P = 0.029, NRI 0.125, IDI 0.032), as well as compared to the clinical model in both the training (P = 0.01, NRI 0.310, IDI 0.09) and test cohorts (P = 0.047, NRI 0.382, IDI 0.085).

Conclusion

the combined model exhibited excellent performance in distinguishing between IMA and INMA in SPNs ≤3 cm.

Identifying malignant mesothelioma by a pathological survey using the São Paulo state hospital cancer registry, Brazil

OBJECTIVE

To review the pathological diagnosis of possible cases and/or hidden cases of malignant mesothelioma (MM) between 2000 and 2012 using the Hospital-Based Cancer Registry database in the state of São Paulo, Brazil.

METHODS

Possible cases were retrieved by assessing the database. Inclusion criteria were being older than 30 years of age and having ICD-O-3 topography and morphology codes related to MM. A board of expert pathologists reviewed the pathology reports and requested paraffin blocks in cases that demanded revision. After staining with calretinin, D2-40, WT-1 (as positive MM markers) and Ber-EP4 and MOC31 (as negative MM markers), cases were divided and studied independently by a pair of pathologists to confirm or discard the diagnosis of MM.

RESULTS

Our sample comprised 482 cases from 25 hospitals, and 130 needed further histological revision. We received 73 paraffin blocks with adequate material. After board analysis, there were 9 cases with a definitive diagnosis of MM, improving the diagnostic rate in 12%. Two cases of previously diagnosed MM were discarded by review.

CONCLUSIONS

Our results confirm that part of MM underdiagnosis and underreporting in Brazil is due to incomplete or mistaken pathological diagnosis.

Thymic gene expression analysis reveals a potential link between HIF-1A and Th17/Treg imbalance in thymoma associated myasthenia gravis

Myasthenia gravis (MG) is an immune-mediated disease frequently associated with thymic changes. Increased T helper 17 (Th17) cell activity and dysfunctional regulatory T (Treg) cells have been demonstrated in subgroups of MG. On the other hand, hypoxia-inducible factor 1 (HIF-1) has been shown to regulate the Th17/Treg balance by inducing Th17 differentiation while attenuating Treg development. To identify the underlying mechanisms of different thymic pathologies in MG development, we evaluated thymic samples from thymoma-associated myasthenia gravis (TAMG), MG with hyperplasia (TFH-MG) and thymoma without MG (TOMA) patients. Differential gene expression analysis revealed that TAMG and TFH-MG cells are associated with different functional pathways. A higher RORC/FOXP3 ratio provided evidence for Th17/Treg imbalance in TAMG potentially related to increased HIF1A. The hypoxic microenvironment in thymoma may be a driver of TAMG by increasing HIF1A. These findings may lead to new therapeutic approaches targeting HIF1A in the development of TAMG.

Postoperative radiotherapy does not improve survival in patients with Masaoka-Koga stage IIB thymomas: A propensity score matching study based on the SEER database

This study, based on a population, explored the prognostic value of postoperative radiotherapy (PORT) for Masaoka-Koga IIB stage thymomas. Patients diagnosed with thymoma from 2004 to 2017 in the Surveillance, Epidemiology, and End Results (SEER) database were included in the retrospective study. Through propensity score matching, the baseline characteristics of the patients were successfully matched to mitigate the selection bias of PORT. Survival rates and survival curves were compared between the PORT and non-PORT groups, with potential confounding factors addressed using a multivariate Cox regression model. In this study, 785 cases of IIB stage thymoma were included from the SEER database, and 303 patients were successfully matched between PORT and non-PORT groups through propensity score matching, with no significant differences in baseline characteristics. In the PORT and non-PORT groups, 10-year overall survival rates were 65.2% versus 59.6%, and cancer-specific survival rates were 87.0% vs. 84.4%, PORT did not yield statistically significant improvements in overall survival (P = .275) or cancer-specific survival (P = .336) for stage IIB thymomas. Based on the SEER database, the results of our study indicated that PORT does not confer a significant survival benefit for IIB stage thymomas.

Long-term follow-up and exploratory analysis of lenvatinib in patients with metastatic or recurrent thymic carcinoma: Results from the multicenter, phase 2 REMORA trial

OBJECTIVES

The main objective of this report was to detail the long-term follow-up data from the REMORA study, which investigated the safety and efficacy of lenvatinib in patients with thymic carcinoma. In addition, an exploratory analysis of the association between relative dose intensity (RDI) and the efficacy of lenvatinib is presented.

MATERIALS AND METHODS

The single-arm, open-label, phase 2 REMORA study was conducted at eight Japanese institutions. Forty-two patients received oral lenvatinib 24 mg once daily in 4-week cycles until the occurrence of intolerable adverse events or disease progression. The REMORA long-term follow-up data were evaluated, including overall survival (OS). RDI was calculated by dividing the actual dose administered to the patient by the standard recommended dose. This trial is registered on JMACCT (JMA-IIA00285) and on UMIN-CTR (UMIN000026777).

RESULTS

The updated median OS was 28.3 months (95 % confidence interval [CI]: 17.1-34.0 months), and the OS rate at 36 months was 35.7 % (95 % CI: 21.7 %-49.9 %). When grouped by RDI of lenvatinib, the median OS was 38.5 months (95 % CI: 31.2-not estimable) in patients with ≥ 75 % RDI and 17.3 months (95 % CI: 13.4-26.2 months) in patients with < 75 % RDI (hazard ratio 0.46 [95 % CI: 0.22-0.98]; P = 0.0406) at 8 weeks. Patients who maintained their lenvatinib dose over 8 weeks had a higher objective response rate than patients whose doses were reduced (75.0 % vs 29.4 %; P = 0.0379). No new safety concerns or treatment-related deaths were reported, and lenvatinib had a tolerable safety profile.

CONCLUSION

This follow-up report updated OS in patients with metastatic or recurrent thymic carcinoma. A higher RDI of lenvatinib at 8 weeks could be associated with improved outcomes.

Good syndrome and cytomegalovirus retinitis: A literature review

Good syndrome (GS) is a rare primary immunodeficiency in adults consisting of hypogammaglobulinemia and thymoma that affects both cellular and humoral immunity. It usually appears in patients between the 4th and 6th decade of life and affects both genders equally. Ophthalmological clinical presentation is highly variable; associations with herpetic keratitis, toxoplasmosis, and cytomegalovirus retinitis (CMVR) have been described. GS associated with CMVR is uncommon. Ophthalmologists may be the first to diagnose systemic disease and change the outcome. Only18 cases of CMVR have been described, most of them unilateral with poor visual outcomes. We discuss the clinical features of CMVR in patients with reported GS, pathogenesis, and outline a work-up for diagnosis. CMVR in an apparently healthy patient should encourage the clinician to search for human immunodeficiency virus (HIV) and non-HIV-associated immunosuppression.

MHD-Net: Memory-Aware Hetero-Modal Distillation Network for Thymic Epithelial Tumor Typing With Missing Pathology Modality

Fusing multi-modal radiology and pathology data with complementary information can improve the accuracy of tumor typing. However, collecting pathology data is difficult since it is high-cost and sometimes only obtainable after the surgery, which limits the application of multi-modal methods in diagnosis. To address this problem, we propose comprehensively learning multi-modal radiology-pathology data in training, and only using uni-modal radiology data in testing. Concretely, a Memory-aware Hetero-modal Distillation Network (MHD-Net) is proposed, which can distill well-learned multi-modal knowledge with the assistance of memory from the teacher to the student. In the teacher, to tackle the challenge in hetero-modal feature fusion, we propose a novel spatial-differentiated hetero-modal fusion module (SHFM) that models spatial-specific tumor information correlations across modalities. As only radiology data is accessible to the student, we store pathology features in the proposed contrast-boosted typing memory module (CTMM) that achieves type-wise memory updating and stage-wise contrastive memory boosting to ensure the effectiveness and generalization of memory items. In the student, to improve the cross-modal distillation, we propose a multi-stage memory-aware distillation (MMD) scheme that reads memory-aware pathology features from CTMM to remedy missing modal-specific information. Furthermore, we construct a Radiology-Pathology Thymic Epithelial Tumor (RPTET) dataset containing paired CT and WSI images with annotations. Experiments on the RPTET and CPTAC-LUAD datasets demonstrate that MHD-Net significantly improves tumor typing and outperforms existing multi-modal methods on missing modality situations.

A new gene signature associated with disulfidptosis that forecasts myasthenia gravis and suggests infiltration of immune microenvironment in thymoma patients

Introduction

The mechanism of thymoma-associated myasthenia gravis (TAMG) is currently unknown, although patients with TAMG experience more severe myasthenic symptoms and have worse prognoses compared to regular thymoma patients. The objective of this research is to create a transcriptome map of TAMG using genes linked to disulfidptosis, detect possible biomarkers, and examine the disparities in the tumor immune microenvironment (TIME) among different thymoma patients. The findings will offer valuable knowledge for personalized treatment alternatives.

Methods

Thymoma samples' RNA-seq data, along with their corresponding clinical data, were acquired from the TCGA database using methods. Next, genes and disulfidptosis-related lncRNAs(DRLs) were chosen through correlation analysis. Then, a prediction model of TAMG was established by LASSO regression. Subsequent to that, an analysis of the mutation data, the tumor mutational burden (TMB), and the assessment of immune and stromal elements within the tumor microenvironment were conducted.

Results

A total of 87 patients diagnosed with thymoma were included in the study, with 29 of them having TAMG. We discovered a group of 325 lncRNAs in this sample that showed significant associations with genes related to disulfidptosis, with 25 of them displaying significantly altered expression. Moreover, utilizing LASSO regression, we constructed a predictive model incorporating 11 DRLs. The analysis revealed an area under the curve (AUC) of 0.934 (CI 0.879-0.989), a cut-off value of 0.797, along with a sensitivity of 82.8 % and specificity of 93.1 %. Furthermore, we examined the TIME in both the high-risk and low-risk groups, and observed noteworthy disparities in B cells, T cells, and APC among the two groups (p < 0.05).

Conclusion

This research offers the initial examination of genes associated with disulfidptosis and TAMG through genomic and transcriptomic analysis. Furthermore, a strong risk forecasting model was created and the significance of TIME in TAMG was also clarified. The discoveries offer significant understanding into the molecular processes of TAMG and present possible indicators for categorizing risk.

Type B thymomas in patients with myasthenia gravis display a distinctive pattern of αβ TCR and IL-7 receptor α expression on CD4+CD8+ thymocytes

Thymoma is closely associated with myasthenia gravis (MG). However, due to the heterogeneity of thymoma and the intricate pathogenesis of MG, it remains unclear why some patients with thymoma develop MG and others do not. In this study, we conducted a comparative phenotype analysis of thymocytes in type B thymomas in patients with MG (MG (+) thymomas) and without MG (MG (-) thymomas) via fluorescence-activated cell sorting (FACS). Our results show that the developmental stages defined by the expression of CD3, CD4, and CD8 were largely maintained in both MG (+) and MG (-) thymomas, with CD4+CD8+ cells constituting the majority of thymocytes in type B thymoma, and no significant difference between this cell population was observed in MG (+) and MG (-) thymomas.We discovered that CD4+CD8+ thymocytes in MG (+) thymomas expressed low levels of αβ TCR and high levels of IL-7 receptor α (IL-7Rα), whereas in MG (-) thymomas, CD4+CD8+ thymocytes exhibited the opposite pattern of αβ TCR and IL-7Rα expression. These results suggest that the positive and negative selection processes of CD4+CD8+ thymocytes might differ between MG (+) thymomas and MG (-) thymomas. The expression of the Helios transcription factor is induced during negative selection and marks a group of T cells that have undergone negative selection and are likely to be deleted due to strong TCR binding with self-peptides/MHC ligands. We observed that the percentage of Helios-positive CD4SP T cells was greater in MG (-) than in MG (+) thymomas. Thus, the differentially regulated selection process of CD4+CD8+ thymocytes, which involves TCR and IL-7/IL-7Rα signaling, is associated with the presence of MG in type B thymomas.

A basaloid carcinoma with multilocular thymic cyst mimicking a mediastinal teratoma

This case report details a rare thymic basaloid carcinoma initially misinterpreted as a mediastinal teratoma, underscoring the diagnostic challenges posed by such tumors. A 71-year-old female presented with an asymptomatic anterior mediastinal tumor discovered incidentally during a routine health examination. Surgical intervention, followed by pathological and immunohistochemical analysis including CK-pan, p63, p40, and CD117 molecules, led to a definitive diagnosis of basaloid carcinoma of the thymus. This case highlights the critical importance of differential diagnosis in mediastinal lesions, especially those presenting with multilocular thymic cysts on chest CT. The subxiphoid video-assisted thoracoscopic surgery enabled complete tumor resection with minimal trauma and favorable postoperative outcomes. The patient opted against further radiotherapy or chemotherapy and she has survived for over eight months without recurrence. This case report contributes to the growing understanding of thymic basaloid carcinoma, a rare and potentially aggressive thymic carcinoma subtype. It emphasizes the necessity for precise surgical techniques and enhanced diagnostic acumen among cardiothoracic surgeons and oncologists.

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

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

Thymic lipofibroadenoma: A case report

Lipofibroadenoma (LFA) is an epithelial tumor. It has been seen rarely in the thymus, and only a handful of cases have been reported. LFA is usually seen in the anterior mediastinum and is defined as a coalescence of epithelial thymic, adipose, and fibrotic tissue. We present a 30-year-old female who presented due to an unrelated traffic accident. An incidental mass was found in her left anterior superior mediastinum. After performing a complete excision, a histologic examination of the excised mass revealed it to be LFA of the thymus, which is extremely rare. The follow-up period was uneventful. LFA is a slow-growing benign tumor and is very similar to fibroadenoma of the breast. The etiology and clinical findings are yet to be well-defined. It was only seen in men in the prior cases. But recent cases, including this one, have also reported female patients. The tumor is mainly observed in the anterior mediastinum, which was also the case in our patient. The gold standard of diagnosis is pathologic examination. Our examination showed strands and nests of thymic parenchyma, including Hassall corpuscles, which separated fibro adipose tissue. Thymectomy is the treatment of choice. It can be performed by either video-assisted thoracic surgery or open surgery. We performed open surgery. The most important prognostic factor for this tumor is staging.

Computed tomography radiomic feature analysis of thymic epithelial tumors: Differentiation of thymic epithelial tumors from thymic cysts and prediction of histological subtypes

PURPOSE

To investigate the value of computed tomography (CT) radiomic feature analysis for the differential diagnosis between thymic epithelial tumors (TETs) and thymic cysts, and prediction of histological subtypes of TETs.

MATERIALS AND METHODS

Twenty-four patients with TETs (13 low-risk and 9 high-risk thymomas, and 2 thymic carcinomas) and 12 with thymic cysts were included in this study. For each lesion, the radiomic features of a volume of interest covering the lesion were extracted from non-contrast enhanced CT images. The Least Absolute Shrinkage and Selection Operator (Lasso) method was used for the feature selection. Predictive models for differentiating TETs from thymic cysts (model A), and high risk thymomas + thymic carcinomas from low risk thymomas (model B) were created from the selected features. The receiver operating characteristic curve was used to evaluate the effectiveness of radiomic feature analysis for differentiating among these tumors.

RESULTS

In model A, the selected 5 radiomic features for the model A were NGLDM_Contrast, GLCM_Correlation, GLZLM_SZLGE, DISCRETIZED_HISTO_Entropy_log2, and DISCRETIZED_HUmin. In model B, sphericity was the only selected feature. The area under the curve, sensitivity, and specificity of radiomic feature analysis were 1 (95% confidence interval [CI]: 1-1), 100%, and 100%, respectively, for differentiating TETs from thymic cysts (model A), and 0.76 (95%CI: 0.53-0.99), 64%, and 100% respectively, for differentiating high-risk thymomas + thymic carcinomas from low-risk thymomas (model B).

CONCLUSION

CT radiomic analysis could be utilized as a non-invasive imaging technique for differentiating TETs from thymic cysts, and high-risk thymomas + thymic carcinomas from low-risk thymomas.

Contrast-enhanced CT-based radiomics differentiate anterior mediastinum lymphoma from thymoma without myasthenia gravis and calcification

AIM

To explore the value of a radiomics model based on enhanced computed tomography (CT) in differentiating anterior mediastinal lymphoma (AML) and thymoma without myasthenia gravis (MG) and calcification.

MATERIALS AND METHODS

The present study analysed patients who were diagnosed histologically with AML and thymoma in three independent institutions. All pre-treatment patients underwent enhanced CT. In the training group of patients from institutions 1 (the First Affiliated Hospital of Kunming Medical University) and 3 (the Yunnan Cancer Hospital), two radiologists independently analysed the enhanced CT images and performed manual segmentation of each tumour. Radiomics features were screened using interobserver interclass coefficient (ICC) analysis, feature correlation analysis, and L1 regularisation. The discriminative efficacy of the logistic regression model was evaluated using receiver operating characteristic (ROC) analysis. Validation group of patients from institution 2 (the Second Affiliated Hospital of Zhejiang University School of Medicine) was used to validate the proposed models.

RESULTS

A total of 114 patients were enrolled in this study and 1,743 radiomics features were extracted from the enhanced CT images. After feature screening, the remaining 37 robust radiomics features were used to construct the model. In the training group, the AUC of the model was 0.987 (95% confidence interval [CI]: 0.976-0.999), the sensitivity, specificity, and accuracy were 0.912, 0.946, and 0.924, respectively. In the validation group, the AUC of the model was 0.798 (95% CI: 0.683-0.913), the sensitivity, specificity, and accuracy were 0.760, 0.700, and 0.743, respectively.

CONCLUSION

The radiomics model created provided effective information to assist in the selection of clinical strategies, thus reducing unnecessary procedures in patients with AML and guiding direct surgery in patients with thymoma to avoid biopsy.

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.

Immunotherapy for Thymomas and Thymic Carcinomas: Current Status and Future Directions

Thymic epithelial tumors are a histologically diverse group of cancers arising from the epithelial compartment of the thymus. These tumors are characterized by a low tumor mutation burden, a lack of actionable genomic changes, and, especially with thymomas, defects in immune tolerance. Surgery is the mainstay of the management of resectable disease, whereas advanced, unresectable tumors are treated with platinum-based chemotherapy. Disease recurrence can occur months to years after frontline treatment. Although several options are available for conventional treatment of recurrent thymic tumors, response rates are generally low, and treatment-related toxicity can affect quality of life. A subset of patients benefit from biologic therapies, but there remains an unmet need for the development of new treatments. Immune checkpoint inhibitors are safe, clinically active, and have contributed to an improvement in survival for patients with a wide variety of cancers. However, the application of these revolutionary treatments for thymic cancers is limited to their use for the management of recurrent thymic carcinoma because of the risk of immune toxicity. In this paper, we review the current uses of immunotherapy for the management of thymic epithelial tumors and highlight potential strategies to improve safety and broaden the application of these treatments for patients with thymic cancers.

Immune tolerance and the prevention of autoimmune diseases essentially depend on thymic tissue homeostasis

The intricate balance of immune reactions towards invading pathogens and immune tolerance towards self is pivotal in preventing autoimmune diseases, with the thymus playing a central role in establishing and maintaining this equilibrium. The induction of central immune tolerance in the thymus involves the elimination of self-reactive T cells, a mechanism essential for averting autoimmunity. Disruption of the thymic T cell selection mechanisms can lead to the development of autoimmune diseases. In the dynamic microenvironment of the thymus, T cell migration and interactions with thymic stromal cells are critical for the selection processes that ensure self-tolerance. Thymic epithelial cells are particularly significant in this context, presenting self-antigens and inducing the negative selection of autoreactive T cells. Further, the synergistic roles of thymic fibroblasts, B cells, and dendritic cells in antigen presentation, selection and the development of regulatory T cells are pivotal in maintaining immune responses tightly regulated. This review article collates these insights, offering a comprehensive examination of the multifaceted role of thymic tissue homeostasis in the establishment of immune tolerance and its implications in the prevention of autoimmune diseases. Additionally, the developmental pathways of the thymus are explored, highlighting how genetic aberrations can disrupt thymic architecture and function, leading to autoimmune conditions. The impact of infections on immune tolerance is another critical area, with pathogens potentially triggering autoimmunity by altering thymic homeostasis. Overall, this review underscores the integral role of thymic tissue homeostasis in the prevention of autoimmune diseases, discussing insights into potential therapeutic strategies and examining putative avenues for future research on developing thymic-based therapies in treating and preventing autoimmune conditions.

Placement of bronchial occluder outside the tracheal tube in a patient combined with airway compression undergoing mediastinal tumors resection: a case report

BACKGROUND

Mediastinal tumors pose a challenging respiratory and circulatory management during anesthesia procedures, there is a risk of circulatory collapse or complete airway obstruction, which in severe cases can lead to cardiac arrest. We reported a case of anesthetic management using a bronchial blocker placed outside the tracheal tube. In this case report, the patient's trachea was so severely compressed that the airway was extremely narrow, only 4 mm at its narrowest point. By reporting the anesthetic management of this patient, we intend to provide an unusual approach for airway management.

CASE PRESENTATION

A 52-year-old male patient was admitted to the hospital due to cough and expectoration for one year. Additionally, the patient experienced chest tightness and asthma after physical activity. The enhanced computed tomography revealed there existed an irregular soft tissue mass in the right upper mediastinum, which significantly compressed the trachea and esophagus. The results of the mediastinal puncture pathology showed the presence of mesenchymal tumors. According to the results above, the patient was diagnosed with a mediastinal tumor and scheduled to undergo tumor resection under general anesthesia. We used a bronchial occluder outside the tracheal tube for general anesthesia. After surgery, the patient received thorough treatment and was subsequently discharged from the hospital.

CONCLUSION

In patients with severe airway compression from a mediastinal tumor airway compression, positioning a bronchial occluder externally to the tracheal tube is an effective method of airway management. However, we still need more clinical practice to help the process become more standardized.

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.

Thymic Adenocarcinoma With Metastasis to the Left Orbit: A Case Report

We present the case of a 57-year-old female who initially presented with a chief complaint of left-sided orbital headaches and associated left eyelid swelling. Initial imaging work-up with CT head/orbit revealed soft tissue enhancement of the left orbital roof, concerning for neoplastic process (primary lymphoma versus extracranial primary tumor versus metastatic tumor). Further imaging studies with CT chest/abdomen/pelvis revealed an anterior mediastinal mass, concerning for possible thymoma versus lymphoma. The patient underwent further consultation with the Hematology/Oncology and Ophthalmology Departments, which recommended definitive biopsies from both sites, which showed matching histologic findings of moderately differentiated enteric-type adenocarcinoma with positive staining for CDX2, an intestinal marker. Thymic carcinomas are rare cancers that account for approximately 0.06% of all malignancies and require a high degree of clinical suspicion. Extrathoracic metastases from thymic carcinomas, especially to the orbit, is a rare occurrence and the exact incidence of this phenomenon is unknown. This case represents the diagnostic challenges associated with a rare cancer type and underscores the importance of a multidisciplinary approach to patient care.

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

BACKGROUND AND PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Re-exploration of prognosis in type B thymomas: establishment of a predictive nomogram model

OBJECTIVE

To explore the risk factors for disease progression after initial treatment of type B thymomas using a predictive nomogram model.

METHODS

A single-center retrospective study of patients with type B thymoma was performed. The Cox proportional hazard model was used for univariate and multivariate analyses. Variables with statistical and clinical significance in the multivariate Cox regression were integrated into a nomogram to establish a predictive model for disease progression.

RESULTS

A total of 353 cases with type B thymoma were retrieved between January 2012 and December 2021. The median follow-up was 58 months (range: 1-128 months). The 10-year progression-free survival (PFS) was 91.8%. The final nomogram model included R0 resection status and Masaoka stage, with a concordance index of 0.880. Non-R0 resection and advanced Masaoka stage were negative prognostic factors for disease progression (p < 0.001). No benefits of postoperative radiotherapy (PORT) were observed in patients with advanced stage and non-R0 resection (p = 0.114 and 0.284, respectively).

CONCLUSION

The best treatment strategy for type B thymoma is the detection and achievement of R0 resection as early as possible. Long-term follow-up is necessary, especially for patients with advanced Masaoka stage and who have not achieved R0 resection. No prognostic benefits were observed for PORT.