Comparison of juvenile and adult myasthenia gravis in a French cohort with focus on thymic histology.

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle fatigability due to acetylcholine receptor (AChR) autoantibodies. To better characterize juvenile MG (JMG), we analyzed 85 pre- and 132 post-pubescent JMG (with a cutoff age of 13) compared to 721 adult MG patients under 40 years old using a French database. Clinical data, anti-AChR antibody titers, thymectomy, and thymic histology were analyzed. The proportion of females was higher in each subgroup. No significant difference in the anti-AChR titers was observed. Interestingly, the proportion of AChR+ MG patients was notably lower among adult MG patients aged between 30 and 40 years, at 69.7%, compared to over 82.4% in the other subgroups. Thymic histological data were examined in patients who underwent thymectomy during the year of MG onset. Notably, in pre-JMG, the percentage of thymectomized patients was significantly lower (32.9% compared to more than 42.5% in other subgroups), and the delay to thymectomy was twice as long. We found a positive correlation between anti-AChR antibodies and germinal center grade across patient categories. Additionally, only females, particularly post-JMG patients, exhibited the highest rates of lymphofollicular hyperplasia (95% of cases) and germinal center grade. These findings reveal distinct patterns in JMG patients, particularly regarding thymic follicular hyperplasia, which appears to be exacerbated in females after puberty.

Micronodular thymic epithelial tumors with lymphoid hyperplasia and mimicking lesions.

Micronodular arrangement of epithelial cells and lymphoid B-cell hyperplasia with follicles are both peculiar histological features in thymic tissue. Such features may especially occur in thymic epithelial tumors. The most common form is called micronodular thymoma with lymphoid stroma. We have recently described some characteristics of thymic micronodular carcinoma with lymphoid hyperplasia, highlighting how this carcinomatous counterpart should not be misdiagnosed as a thymoma. In this review, we discuss these two entities but also other mimics, which may occur in the anterior mediastinum. These mimics include various types of cellular micronodules and lymphoid backgrounds encompassing a wide range of mediastinal lesions. Non-neoplastic lesions, such as thymic nodular epithelial hyperplasia, thymic lymphoid hyperplasia, or sarcoidosis, as well as tumors of very varying aggressiveness, such as micronodular thymic epithelial tumors, low-grade lymphoma, seminoma, or lymphoepithelial carcinoma, are discussed. We show how these lesions may be misleading and we describe how a correct diagnostic may be obtained in current practice.

Doppler echocardiography for surveillance of acute cardiac allograft rejection: a 28-year single-center experience.

Background: Endomyocardial biopsies (EMB) are recommended for the detection of acute cardiac rejection (ACR) despite limited sensitivity. We report the long-term post-transplant results of Doppler echocardiography as a noninvasive alternative of routine EMB. Methods: Two cohorts of heart transplantation (HT) recipients were chronologically defined as follows: the Dual Monitoring Cohort (DMC) from January 1990 to December 1997 included patients who underwent routine EMB and Doppler echocardiography within 24 hours for ACR surveillance; and the "Echo-First Cohort" (EFC), including patients transplanted from January 1998 to December 2018 with Doppler echocardiography as first-line approach for ACR surveillance. Echocardiographic measurements of interest were collected: early diastolic (E) wave peak velocity; pressure half time (PHT) and isovolumetric relaxation time (IVRT). Post-transplant outcomes were reviewed and the Kaplan-Meier approach was used for survival estimates. Inter-operator variability for ultrasound measurements was investigated. Data were collected from medical records from January 2019 to December 2020. Results: A total of 228 patients were included, 99 patients in the DMC and 129 in the EFC. Overall, 5-, 10- and 15-year survival rates were 65.4%, 55.5% and 44.1% respectively, without any significant difference between the two cohorts (log rank test, P=0.71). Echocardiography variables and EMB findings were associated with a mean area under the receiver operating characteristic curve (AUC-ROC) of 0.73 [95% confidence interval (CI): 0.54-0.91], 0.74 (95% CI: 0.54-0.94) and 0.75 (95% CI: 0.57-0.94) respectively for E wave, PHT and IVRT. IVRT and PHT were significantly decreased, and E wave significantly increased, in case of histologically proven ACR. Inter-operator variability was not significant for E wave and IVRT measurements (P=0.13 and 0.30 respectively). Conclusions: Doppler echocardiography as a first-line method for surveillance of ACR did not impair long-term results after HT. These findings suggest that this non-invasive approach might be a reasonable alternative to systematic EMB, limiting risk and improving the quality of life.

Intimal granulomatous angiitis in sarcoid pulmonary vasculitis: worth remembering.

Intimal granulomatous angiitis is a facet of pulmonary sarcoidosis vasculitis that has almost been forgotten. Its observation may offer new understanding of the various patterns of pulmonary hypertension associated with sarcoidosis. https://bit.ly/3g6Ms76.

Retrospective study of outcomes after extended resection for tracheobronchial adenoid cystic carcinoma.

OBJECTIVE: Tracheobronchial adenoid cystic carcinoma is a rare, slow-growing malignancy with a considerable propensity for local extension that may require complex airway resection to achieve tumor-free margins. The objective of this study was to assess whether our experience supports complex airway resection for tracheobronchial adenoid cystic carcinoma. METHODS: Consecutive patients who underwent curative resection for tracheobronchial adenoid cystic carcinoma at our institution between 1970 and 2019 were included retrospectively and classified as having had complex or standard resection. Complex surgery included total tracheal replacement, associated esophageal resection, pneumonectomy, total laryngectomy with tracheal resection, and carinal resection. Standard surgery included tracheal resection, bronchoplastic resection, lobectomy, and bilobectomy. We obtained data from medical records, referring physicians, patients, relatives, and public death records. RESULTS: Of 59 included patients, 38 had complex and 21 had standard surgery. All 4 (6.8%) patients who died postoperatively had undergone complex surgery. Postoperative morbidity was 32.2% overall and was significantly higher after complex surgery (P = .043). Overall 5- and 10-year survival rates were 81.5% and 60.2%, with no significant differences between groups (P = .31). By univariate analysis, T4 tumor and microscopically detectable tumor in the operative specimen margins and gross tumor in the operative specimen margins were associated with poorer survival (P < .05). In the subgroup with microscopically detectable tumor resection, survival was significantly better with adjuvant radiotherapy (P < .05). CONCLUSIONS: Complex resection for extended tracheobronchial adenoid cystic carcinoma may achieve local control and satisfying long-term survival. However, this demanding procedure is associated with high postoperative morbidity and mortality rates. Because adjuvant radiotherapy improved outcomes after resection resulting in microscopically detectable tumor in the operative specimen margins, expected outcomes after resection with no detectable tumor in the margins must be compared to those after resection resulting in microscopically detectable tumor in the margins plus radiotherapy, according to the operative risk.

Unexpected Cardiotoxicity in Patients With HER2-Mutant NSCLC Treated With Trastuzumab Deruxtecan: A Case Report.

Antibody-drug conjugates targeting receptor tyrosine-protein kinase erbB-2 (ERBB2, HER2) have emerged as promising targeted options for HER2-mutant NSCLC. Among antibody-drug conjugates targeting HER2, trastuzumab deruxtecan was found to have the most impressive efficacy and is a potential new standard of care. Drug-related interstitial lung disease remains a serious unpredictable identified risk for patients treated with trastuzumab deruxtecan, requiring careful monitoring and multidisciplinary management. We report the first two cases of drug-related cardiotoxicity with acute myocarditis that developed after the first trastuzumab deruxtecan cycle. Routine cardiovascular risk screening is advisable, with close collaboration between cardiology specialists and oncologists.

Feasibility and long-term outcomes of surgery for primary thoracic synovial sarcoma.

OBJECTIVES: Primary thoracic synovial sarcoma (SS) is a rare, high-grade, malignancy. Involvement of vital organs is frequent and may decrease the benefits of surgical resection. We reviewed our practice at a highly experienced thoracic-surgery centre to assess early- and long-term outcomes after surgery. METHODS: We conducted a retrospective, observational, single-centre study of patients undergoing curative-intent surgery for primary thoracic SS between 1 January 2000 and 31 January 2021 as part of a multidisciplinary management. We assessed demographics, medical history, histopathology and follow-up information. RESULTS: We enrolled 20 patients (13 males) with a median age of 40 years old and a median tumour size of 11 cm. Neoadjuvant chemotherapy was administered to 13 patients. Surgery consisted in extrapleural pneumonectomy (n = 7), extrapleural lobectomy (n = 5), chest wall resection (n = 4) or tumour resection (n = 4). R0 resection was achieved in 16 (80%) patients. Adjuvant therapy was given to 13 patients. 6 patients developed postoperative complications. The median hospital stay was 11.5 days. Overall survival at 2 and 5 years was 51% and 22%, respectively; median overall survival was 25 months and median disease-free survival was 8.5 months. Relapses occurred in 15 patients. By univariate analysis, incomplete resection was the only significant predictor of survival (P = 0.01). CONCLUSIONS: Primary thoracic SS is an aggressive disease. Surgery included in a multimodal treatment may contribute to achieving a good outcome, providing that an R0 resection is obtained. Given the considerable technical challenges of surgery, patient selection and referral to an experienced centre are crucial to minimize morbidity and mortality.

Metastatic pulmonary carcinoids with EML4-ALK fusion response to ALK inhibitors: two case reports and review of literature.

Background: Pulmonary carcinoids (PC), including typical (TC) and atypical carcinoids (AC), are low-grade neuroendocrine tumors (NETs) which account for 1-5% of all lung tumors. Due to the low prevalence of PC and extreme rarity of anaplastic lymphoma kinase (ALK) rearrangements in patients with PC, the advances in targeted therapy development in PC are still limited and there is no standard treatment. Even though in patients with PC harboring ALK rearrangements there is a room for a success in targeted therapy. To our knowledge, case 1 was the first report to detect ALK gene p.I1171N mutation after taking alectinib and sensitive to ceritinib in patients with atypical carcinoid. Case Description: Herein, we report the cases of 2 non-smoking patients, 51 year-old female with tumor in left lower lobe and 49 year-old female with tumor in right upper lobe, both with metastatic PC who harbored EML4-ALK fusion and were sensitive to small-molecule ALK inhibitors. The first patient initially received alectinib, then therapy was switched to ceritinib after developing drug resistance due to the missense mutation of ALK gene p.I1171N mutation in exon 22 detected by next-generation sequencing (NGS), and finally died of intracranial disease progression. The second patient also received alectinib, and her treatment is currently ongoing with good effect and tolerance. After conducting comprehensive review of literature, we found that 14 lung NETs with ALK rearrangements have been reported to date. The clinical outcome was partial response for 6 NETs patients and 5 patients exhibited stable disease after treatment with ALK inhibitors. Conclusions: According to the effectiveness of ALK inhibitors in our cases and previous articles, we recommend alectinib for the first-line treatment of metastatic PC with EML4-ALK fusion and highlight the need for molecular profiling of metastatic lung NETs patients and that ALK inhibitors are feasible in the treatment for metastatic lung NETs patients with ALK rearrangements. Finally, further studies to assess the real prevalence of ALK gene fusions and their spectrum of sensitivity to different ALK inhibitors are needed in larger cohorts.

Treatment strategies for thymic carcinoma in a real-life setting. Insights from the RYTHMIC network.

BACKGROUND: Thymic carcinomas are aggressive and difficult to treat a subset of thymic epithelial tumours that represent a heterogeneous group of rare intrathoracic malignancies. The treatment strategy of thymic carcinomas is based on whether surgical resection may be achieved, which represents the most significant favourable prognostic factor on survival. For this study, we took advantage of the unique prospective Réseau tumeurs THYMiques et Cancer (RYTHMIC) database to describe baseline characteristics, analyse treatment strategies in light of existing guidelines and provide landmark patient outcomes data with regards to response and survival of patients in a real-life clinical practice setting. METHODS: Inclusion criteria for this analysis were the following: (1) histologically-confirmed thymic carcinomas - excluding neuroendocrine tumours-after pathological review by the RYTHMIC pathology panel, (2) discussion of the case at the RYTHMIC multidisciplinary tumour board, (3) at least one active treatment modality. RESULTS: A total of 213 patients were analysed. Overall, 60 (28%) patients were considered as surgical candidates upfront, 91 (43%) patients received primary chemotherapy, and 62 (29%) patients received exclusive chemotherapy. Median overall survival (OS) was 49.2 months (IC95%: 34.8-63.6); OS was significantly longer in patients with a lower stage at diagnosis (p < 0.001), who were operated on upfront, as opposed to patients who received primary or exclusive chemotherapy (p < 0.001). Surgery, conducted upfront or after primary chemotherapy, was significantly associated with more prolonged OS (p < 0.001); complete resection and postoperative radiotherapy were also predictors of better outcome (p = 0.018 and p = 0.051, respectively). CONCLUSIONS: Our cohort is the first to analyse in-depth outcomes and treatment strategies in a prospective cohort of consecutive patients with thymic carcinoma. While we confirm the major prognostic impact of surgery, our data highlight the need for optimised multidisciplinary management and innovative therapies as the survival of patients remains limited.

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

This overview of the fifth edition of the WHO classification of thymic epithelial tumors (including thymomas, thymic carcinomas, and thymic neuroendocrine tumors [NETs]), mediastinal germ cell tumors, and mesenchymal neoplasms aims to (1) list established and new tumor entities and subtypes and (2) focus on diagnostic, molecular, and conceptual advances since publication of the fourth edition in 2015. Diagnostic advances are best exemplified by the immunohistochemical characterization of adenocarcinomas and the recognition of genetic translocations in metaplastic thymomas, rare B2 and B3 thymomas, and hyalinizing clear cell carcinomas. Advancements at the molecular and tumor biological levels of utmost oncological relevance are the findings that thymomas and most thymic carcinomas lack currently targetable mutations, have an extraordinarily low tumor mutational burden, but typically have a programmed death-ligand 1high phenotype. Finally, data underpinning a conceptual advance are illustrated for the future classification of thymic NETs that may fit into the classification scheme of extrathoracic NETs. Endowed with updated clinical information and state-of-the-art positron emission tomography and computed tomography images, the fifth edition of the WHO classification of thymic epithelial tumors, germ cell tumors, and mesenchymal neoplasms with its wealth of new diagnostic and molecular insights will be a valuable source for pathologists, radiologists, surgeons, and oncologists alike. Therapeutic perspectives and research challenges will be addressed as well.

Mediastinal tumours and pseudo-tumours: a comprehensive review with emphasis on multidisciplinary approach.

The diagnosis of a mediastinal mass may be challenging for clinicians, since lesions arising within the mediastinum include a variety of disease entities, frequently requiring a multidisciplinary approach. Age and sex represent important information, which need to be integrated with imaging and laboratory findings. In addition, the location of the mediastinal lesion is fundamental; indeed, we propose to illustrate mediastinal diseases based on the compartment of origin. We consider that this structured approach may serve as hint to the diagnostic modalities and management of mediastinal diseases. In this review, we present primary mediastinal tumours in the evolving context of new diagnostic and therapeutic tools, with recently described entities, based on our own experience with >900 cases encountered in the past 10 years.

Can MRI differentiate surrounding vertebral invasion from reactive inflammatory changes in superior sulcus tumor?

OBJECTIVES: Vertebral invasion is a key prognostic factor and a critical aspect of surgical planning for superior sulcus tumors. This study aims to further evaluate MRI features of vertebral invasion in order to distinguish it from reactive inflammatory changes. METHODS: Between 2000 and 2016, a retrospective study was performed at a single institution. All patients with superior sulcus tumors undergoing surgery, including at least two partial vertebrectomies, were included. An expert radiologist evaluated qualitative and quantitative MRI signal intensity characteristics (contrast-to-noise ratio [CNR]) of suspected involved and non-involved vertebrae. A comparison of CNR of invaded and sane vertebrae was performed using non-parametric tests. Imaging data were correlated with pathological findings. RESULTS: A total of 92 surgical samples of vertebrectomy were analyzed. The most specific sequences for invasion were T1 and T2 weighted (92% and 97%, respectively). The most sensitive sequences were contrast enhanced T1 weighted fat suppressed and T2 weighted fat suppressed (100% and 80%). Loss of extrapleural paravertebral fat on the T1-weighted sequence was highly sensitive (100%) but not specific (63%). Using quantitative analysis, the optimum cut-off (p < 0.05) to distinguish invasion from reactive inflammatory changes was CNR > 11 for the T2-weighted fat-sat sequence (sensitivity 100%), CNR > 9 for contrast-enhanced T1-weighted fat-suppressed sequence (sensitivity 100%), and CNR < - 30 for the T1-weighted sequence (specificity 97%). Combining these criteria, 23 partial vertebrectomies could have been avoided in our cohort. CONCLUSION: Qualitative and quantitative MRI analyses are useful to discriminate vertebral invasion from reactive inflammatory changes. KEY POINTS: • Abnormal signal intensity in a vertebral body adjacent to a superior sulcus tumor may be secondary to direct invasion or reactive inflammatory changes. • Accurate differentiation between invasion and reactive inflammatory changes significantly impacts surgical planning. T1w and T2w are the best sequences to differentiate malignant versus benign bone marrow changes. The use of quantitative analysis improves MRI specificity. • Using contrast media improves the sensitivity for the detection of tumor invasion.

Concomitant mutation status of ALK-rearranged non-small cell lung cancers and its prognostic impact on patients treated with crizotinib.

BACKGROUND: In non-small cell lung cancer (NSCLC), anaplastic lymphoma kinase (ALK) rearrangement characterizes a subgroup of patients who show sensitivity to ALK tyrosine kinase inhibitors (TKIs). However, the prognoses of these patients are heterogeneous. A better understanding of the genomic alterations occurring in these tumors could explain the prognostic heterogeneity observed in these patients. METHODS: We retrospectively analyzed 96 patients with NSCLC with ALK detected by immunohistochemical staining (VENTANA anti-ALK(D5F3) Rabbit Monoclonal Primary Antibody). Cancer tissues were subjected to next-generation sequencing using a panel of 520 cancer-related genes. The genomic landscape, distribution of ALK fusion variants, and clinicopathological characteristics of the patients were evaluated. The correlations of genomic alterations with clinical outcomes were also assessed. RESULTS: Among the 96 patients with immunohistochemically identified ALK fusions, 80 (83%) were confirmed by next-generation sequencing. TP53 mutation was the most commonly co-occurring mutation with ALK rearrangement. Concomitant driver mutations [2 Kirsten rat sarcoma viral oncogene homolog (KRAS) G12, 1 epidermal growth factor receptor (EGFR) 19del, and 1 MET exon 14 skipping] were also observed in 4 adenocarcinomas. Echinoderm microtubule associated protein-like 4 (EML4)-ALK fusions were identified in 95% of ALK-rearranged patients, with 16.2% of them also harboring additional non-EML4-ALK fusions. Nineteen non-EML4 translocation partners were also discovered, including 10 novel ones. Survival analyses revealed that patients concurrently harboring PIK3R2 alterations showed a trend toward shorter progression-free survival (6 vs. 13 months, P=0.064) and significantly shorter overall survival (11 vs. 32 months, P=0.004) than did PIK3R2-wild-type patients. Patients with concomitant alterations in PI3K the signaling pathway also had a shorter median overall survival than those without such alterations (23 vs. 32 months, P=0.014), whereas progression-free survival did not differ significantly. CONCLUSIONS: The spectrum of ALK-fusion variants and the landscape of concomitant genomic alterations were delineated in 96 NSCLC patients. Our study also demonstrated the prognostic value of concomitant alterations in crizotinib-treated patients, which could facilitate improved stratification of ALK-rearranged NSCLC patients in the selection of candidates who could optimally benefit from therapy.

Micronodular thymic carcinoma with lymphoid hyperplasia: relevance of immunohistochemistry with a small panel of antibodies for diagnosis-a RYTHMIC study.

Micronodular thymic carcinoma with lymphoid hyperplasia (MNTCLH) is a rare form of thymic carcinoma. We present the experience of RYTHMIC, the French national network devoted to the treatment of thymic epithelial tumors through multidisciplinary tumor boards with a review of all tumors by pathologists for classification and staging. Six cases of MNTCLH were diagnosed during a review of 1007 thymic epithelial tumors. Histologically, epithelial cells with atypia and mitoses formed micronodules that were surrounded by an abundant lymphoid background with follicles. There was neither obvious fibro-inflammatory stroma nor necrosis. Spindle cells areas were common. Initial diagnosis was micronodular thymoma in two cases, cellular atypia being overlooked, eclipsed by the micronodular pattern. Immunohistochemistry with a panel of five antibodies showed that cytokeratins (AE1-AE3) and p63-positive epithelial cells also expressed CD5 and that there was no TdT-positive cells within the tumors. CD20 highlighted the lymphoid hyperplasia. Additionally epithelial cells also expressed CD117 and diffusely Glut 1. Twenty-seven micronodular thymomas with lymphoid stroma diagnosed during the same period did not show the CD5 and CD117 positivities seen in MNTCLH and contained TdT-positive lymphocytes. Three of the 6 patients with MNTCLH had adjuvant radiotherapy. Three patients with follow-up information were alive without recurrence at 38, 51, and 95 months. Our study shows that immunohistochemistry, such as that used in the RYTHMIC network with a small panel of antibodies, may easily help to confirm the correct diagnosis of MNTCLH, a rare and low-aggressive form of thymic carcinoma, and avoid the misdiagnosis of micronodular thymoma.

Immunodynamics of explanted human tumors for immuno-oncology.

Decision making in immuno-oncology is pivotal to adapt therapy to the tumor microenvironment (TME) of the patient among the numerous options of monoclonal antibodies or small molecules. Predicting the best combinatorial regimen remains an unmet medical need. Here, we report a multiplex functional and dynamic immuno-assay based on the capacity of the TME to respond to ex vivo stimulation with twelve immunomodulators including immune checkpoint inhibitors (ICI) in 43 human primary tumors. This "in sitro" (in situ/in vitro) assay has the potential to predict unresponsiveness to anti-PD-1 mAbs, and to detect the most appropriate and personalized combinatorial regimen. Prospective clinical trials are awaited to validate this in sitro assay.

Specific Genomic Alterations in High-Grade Pulmonary Neuroendocrine Tumours with Carcinoid Morphology.

INTRODUCTION: High-grade lung neuroendocrine tumours with carcinoid morphology have been recently reported; they may represent the thoracic counterparts of grade 3 digestive neuroendocrine tumours. We aimed to study their genetic landscape including analysis of tumoral heterogeneity. METHODS: Eleven patients with high-grade (>20% Ki-67 and/or >10 mitoses) lung neuroendocrine tumours with a carcinoid morphology were included. We analysed copy number variations, somatic mutations, and protein expression in 16 tumour samples (2 samples were available for 5 patients allowing us to study spatial and temporal heterogeneity). RESULTS: Genomic patterns were heterogeneous ranging from "quiet" to tetraploid, heavily rearranged genomes. Oncogene mutations were rare and most genetic alterations targeted tumour suppressor genes. Chromosomes 11 (7/11), 3 (6/11), 13 (4/11), and 6-17 (3/11) were the most frequently lost. Altered tumour suppressor genes were common to both carcinoids and neuroendocrine carcinomas, involving different pathways including chromatin remodelling (KMT2A, ARID1A, SETD2, SMARCA2, BAP1, PBRM1, KAT6A), DNA repair (MEN1, POLQ, ATR, MLH1, ATM), cell cycle (RB1, TP53, CDKN2A), cell adhesion (LATS2, CTNNB1, GSK3B) and metabolism (VHL). Comparative spatial/temporal analyses confirmed that these tumours emerged from clones of lower aggressivity but revealed that they were genetically heterogeneous accumulating "neuroendocrine carcinoma-like" genetic alterations through progression such as TP53/RB1 alterations. CONCLUSION: These data confirm the importance of chromatin remodelling genes in pulmonary carcinoids and highlight the potential role of TP53 and RB1 to drive the transformation in more aggressive high-grade tumours.

Non-small cell lung carcinomas with CTNNB1 (beta-catenin) mutations: A clinicopathological study of 26 cases.

Beta-catenin, encoded by the CTNNB1 gene, plays an important role in cell proliferation. Mutations of CTNNB1 are oncogenic in several tumor types and are often associated with a nuclear abnormal expression. However, such mutations have only rarely been reported in non-small cell lung carcinomas and their clinical signification is not well described. Our study was conducted on 26 CTNNB1-mutated non-small cell lung carcinomas. Tumors were routinely tested by next generation sequencing for mutations in exon 3 of CTNNB1 gene. Twenty three cases were from a series of 925 tumors (2.48%). The hospital files and pathological data, from surgical samples (n = 16), small biopsies (n = 5) and trans-bronchial fine needle aspirations (n = 5), were reviewed. Immunohistochemistry was performed with an anti-beta-catenin antibody. There were 10 female and 16 male patients aged 52 to 83. Eleven of 25 patients were no-smoking or light smokers. Three cases were diagnosed while under treatment with EGFR tyrosine kinase inhibitor. There were 25 adenocarcinomas and 1 squamous cell carcinoma. Most adenocarcinomas had a papillary component and were TTF1-positive. One case was a well-differentiated fetal adenocarcinoma. Eleven cases (42%) with CTNNB1 mutations showed associated EGFR mutations. The frequency of CTNNB1 mutations was higher among EGFR mutated carcinomas. Immunohistochemistry showed heterogeneous nuclear or cytoplasmic abnormal expression. Our study shows that CTNNB1 mutations mostly occur in TTF1-positive adenocarcinomas with a papillary pattern. These mutations are often associated with EGFR mutations and possibly interfer in the mechanism of resistance to tyrosine kinase inhibitors. Our experience suggests that immuno-histochemistry cannot be used for screening.

Immune biomarkers in thymic epithelial tumors: expression patterns, prognostic value and comparison of diagnostic tests for PD-L1.

BACKGROUND: Immunotherapy is currently under investigation in B3 Thymoma (TB3) and Thymic Carcinoma (TC). PD-L1 expression has been evaluated on a limited number of patients with selected antibodies. We aimed to analyze cohort of TB3 and TC with a panel of antibodies to assess the prevalence of PD-L1 expression, its prognostic value and to set up a reproducible test. METHODS: We retrospectively studied 103 patients samples of FFPE histologically confirmed TB3 (n = 53) and TC (n = 50) by expert pathologists within the RYTHMIC national network. We compared PD-L1, PD1, CD8 and PD-L2 expression and performed correlation with tumor types and patients outcomes. Four PD-L1 antibodies were tested, three of them validated as companion tests in lung cancer, one tested on two automates on whole section of tumors. We evaluated the percentage and intensity of both epithelial and immune stained cells. RESULTS: TB3 epithelial cells had a higher and more diffuse expression of PD-L1 than TC regardless the antibodies tested (p < 0.0001). Three out of four antibodies targeting PD-L1 tested on the DAKO autostainer gave similar staining. Concordance between antibodies was lower for PD-L1 staining on immune cells with no significant difference between TB3 and TC except on E1L3N antibody. PD-L2 antibody stained no tumor epithelial cells. High PD-L1 expression was correlated with a better overall survival for TB3 and was not correlated with tumor staging. CONCLUSION: Frequent PD-L1 expression, particularly in TB3, paves the way for immunotherapy in TET (Thymic Epithelial Tumor). Otherwise, we have set up three reproducible LDT (laboratory-developed test) for four PD-L1 antibodies.

Redefining malignant pleural mesothelioma types as a continuum uncovers immune-vascular interactions.

BACKGROUND: Malignant Pleural Mesothelioma (MPM) is an aggressive disease related to asbestos exposure, with no effective therapeutic options. METHODS: We undertook unsupervised analyses of RNA-sequencing data of 284 MPMs, with no assumption of discreteness. Using immunohistochemistry, we performed an orthogonal validation on a subset of 103 samples and a biological replication in an independent series of 77 samples. FINDINGS: A continuum of molecular profiles explained the prognosis of the disease better than any discrete model. The immune and vascular pathways were the major sources of molecular variation, with strong differences in the expression of immune checkpoints and pro-angiogenic genes; the extrema of this continuum had specific molecular profiles: a "hot" bad-prognosis profile, with high lymphocyte infiltration and high expression of immune checkpoints and pro-angiogenic genes; a "cold" bad-prognosis profile, with low lymphocyte infiltration and high expression of pro-angiogenic genes; and a "VEGFR2+/VISTA+" better-prognosis profile, with high expression of immune checkpoint VISTA and pro-angiogenic gene VEGFR2. We validated the gene expression levels at the protein level for a subset of five selected genes belonging to the immune and vascular pathways (CD8A, PDL1, VEGFR3, VEGFR2, and VISTA), in the validation series, and replicated the molecular profiles as well as their prognostic value in the replication series. INTERPRETATION: The prognosis of MPM is best explained by a continuous model, which extremes show specific expression patterns of genes involved in angiogenesis and immune response.

SMARCA4-deficient Thoracic Sarcomas: Clinicopathologic Study of 30 Cases With an Emphasis on Their Nosology and Differential Diagnoses.

SMARCA4-deficient thoracic sarcoma (SMARCA4-DTS) is a recently described entity with an aggressive clinical course and specific genetic alterations of the BAF chromatin remodeling complex. In the present study, we reviewed the clinical and pathologic features of 30 cases of SMARCA4-DTS, discussed its main differential diagnoses and the challenging diagnostic scenarios that the average pathologist may face. In addition, we tested the specificity of the "SMARCA4-DTS immunohistochemical signature" (co-loss of SMARCA4 and SMARCA2 with overexpression of SOX2) in a large cohort of intrathoracic malignancies. Patients ranged from 28 to 90 years of age (median: 48 y), with a marked male predominance (male:female=9:1) and they were usually smokers. Tumors were generally large compressive masses located in the mediastinum (n=13), pleura (n=5), lung (n=2) or in 2 or more of these topographies (n=10). Treatment strategies were varied, including 1 case treated with EZH2 inhibitors. Median overall survival was 6 months. Histologically, tumors were poorly differentiated frequently showing rhabdoid features. A subset of cases showed a focal myxoid stroma (7%, n=2/30) and rare cases displayed a previously unreported pattern simulating desmoplastic small round cell tumors (7%, n=2/30). Making a diagnosis was challenging when dealing with biopsy material from massively necrotic tumors and in this setting the expression of SOX2, CD34, and SALL4 proved useful. All tested cases displayed concomitant loss of SMARCA4 and SMARCA2 and most tumors expressed epithelial markers (Pan-keratin or EMA) (n=29/30), SOX2 (n=26/27), and CD34 (n=17/27). SMARCB1 expression was retained in all cases (23/23). SALL4 and Claudin-4 were expressed in a subset of cases (n=7/21 and 2/19, respectively). TTF-1 and P63 were focally expressed in 1 case each. P40 and NUT were not expressed (0/23 and 0/20, respectively) The SMARCA4-DTS immunohistochemical signature was both sensitive and specific, with only a subset of small cell carcinoma of the ovary hypercalcemic type showing overlapping phenotypes. Our study confirms and expands the specific features of SMARCA4-DTS, emphasizing the fact that they can be straightforwardly identified by pathologists.