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AIMS Little is known regarding the histopathological and molecular features of lung adenocarcinoma skin metastases. Our study is the largest, to our knowledge, to comprehensively explore these to date. METHODS AND RESULTS We performed a retrospective cohort study analysing 42 lung adenocarcinoma skin metastasis samples obtained from a database of 2659 lung adenocarcinomas collected between 2010 and 2020. EGFR exon 19 deletion was detected in one patient and KRAS mutations were detected in 12 (33.3%) patients. The programmed cell death ligand 1 (PD-L1) tumour proportion score was

Immunohistochemical demonstration of neuroendocrine differentiation is often performed in routine diagnostic practice for lung neuroendocrine carcinoma. However, these carcinomas are often crushed, especially on small specimens. The value of immunohistochemistry on crushed areas is not known. We aimed to assess the value of immunohistochemical markers in crushed areas. We performed a retrospective study of 299 patients with a diagnosis of pulmonary neuroendocrine carcinoma. We showed that the markers TTF-1, synaptophysin, chromogranin A, CD56, and INSM1 were more often negative in crushed areas compared with well-preserved areas. The proliferation index with anti-Ki67 was decreased but remained on average around 90%. For all markers, the percentage of labeled cells was lower than in the preserved areas. Finally, we show that cases without labeling in the crushed areas and maintained labeling in the non-crushed areas have a lower percentage of labeling than cases without this labeling mismatch. Finally, there were no false positives of these stains. Neuroendocrine markers are valid in crushed areas when positive. However, the percentage of labeled cells may be lower than on preserved areas and lead to false negatives. Finally, the proliferation index, although decreased, remains close to that on preserved areas.

The bone is a frequent localization for lung non-small cell cancer metastasis; decalcification is required to permit tissue section. Pre-analytical conditions can influence the detection of immunohistochemical markers. The aim of our work is to evaluate PD-L1 expression in samples with delayed fixation and in decalcified tissue with chelating agent or acid at different time. Tumor-expressing PD-L1 and placental tissue were fixed at different times or decalcified with an acid decalcifier or EDTA for different durations. For 22C3 antibody, when tissues were decalcified with DC3, there was a significant decrease in the percentage of tumor cells or placental villi stained which after 4 h (p = 0.035 at 4 h). When EDTA is used for 22C3 antibody, there was a slight decrease in the percentage of stained tumor cells or villi but although there was a trend (p = 0.058 at 20 h), this was never statistically significant. For E1L3N antibody, when tissues were decalcified either with DC3 or EDTA, there was no significant decrease for the proportion of stained tumor cells or placental villi, neither for staining intensity for the first 24 h. The proportion of placental villi and tumor stained or intensity of staining was not significantly lower for any sample after delayed fixation also at 24 h for both PD-L1 clones. Delayed fixation does not affect the proportion of stained cell and intensity with PD-L1 immunohistochemistry. Decalcification also performed with EDTA lower the proportion and intensity of stained cells with PD-L1 immunohistochemistry.

The heterogeneity of PD-L1 expression and its relationship with histopathological subtype has recently been shown on primary tumor but has not been evaluated on metastases. The aim of our work is to analyze PD-L1 expression within each histopathological pattern on resected metastases.136 patients were included in this retrospective study. Immunohistochemistry was performed with 22C3 laboratory-developed test. The Tumor Proportion Score was evaluated on each subtype.The most frequent major histopathological subtype was solid (n = 69, 50.7 %), followed by acinar (n = 37, 27.2 %), micropapillary (n = 14, 10.3 %) and papillary (n = 10, 7.3 %). Mean percentage of PD-L1 expression for each subtype was at 28+/-4.8 % for solid subtype, 5.3+/-1.9 % for acinar subtype, 5+/-1.9 % for papillary subtype and 23.6+/-4.1 % for micropapillary subtype. Mean percentage of PD-L1 expression was different between solid pattern and acinar pattern (p 0.001), solid pattern and papillary pattern (p = 0.007), micropapillary pattern and acinar pattern (p 0.001) and micropapillary pattern and papillary pattern (p = 0.015).To conclude, we have showed firstly that several patterns are present in metastases of lung adenocarcinoma, secondly that the evaluation of patterns and PD-L1 stain on different patterns is reproducible, thirdly that pattern heterogeneity is related to PD-L1 staining, fourthly that in metastatic lung adenocarcinoma with at least two patterns, solid and micropapillary subtypes have higher levels of PD-L staining, fifthly that PD-L1 heterogeneity between different patterns is not a rare event. These results might explain discrepancies of PD-L1 results between biopsies and surgical samples and the fact that some patients might respond to checkpoint inhibitors even though PD-L1 expression is low or absent.

Lung adenocarcinoma is a heterogeneous tumor made of different architectural patterns. These tumors are classified into subtypes according to the predominant pattern in the primary tumor because the predominant pattern is related to overall survival. The prognostic role of these subtypes in stage IV disease is not well known, and most lung adenocarcinomas are diagnosed at the stage of metastatic disease. We aimed to evaluate the prognostic role of histopathological subtypes in lung adenocarcinoma metastases in a retrospective study of 253 patients with clinical, histopathological and molecular data. The presence of the solid subtype was related to overall survival (p = 0.045); the median overall survival was 6.8 months (95 % confidence interval (95 %CI) 4.4-9.1) when present and 11.1 months (95 %CI 8.6-21.3) when absent. Thyroid transcription factor 1 (TTF-1) immunohistochemistry was related to overall survival (p < 0.001); the median overall survival was 11.2 months (95 %CI 8.4-17.7) when positive and 4 months (95 %CI 2.3-5.7) when negative. On multivariate analysis, the presence of the solid subtype (p = 0.0036, hazard ratio (HR) 1.55, 95 %CI 1.03-2.34), TTF-1 positivity (p = 0.044, HR 0.64, 95 %CI 0.42-0.98), age

Lung adenocarcinoma grading has gained interest in the past years. Recently a three-tier tumor grading was proposed showing that it is related to patients' prognosis. Nevertheless, the underlying molecular basis of this morphological grading remains partly unknown. The aim of our work is to take advantage of The Cancer Genome Atlas lung adenocarcinoma (TCGA_LUAD) cohort to describe the molecular data associated to tumor grading. We performed a study on publicly available data of the TCGA database first by assessing a tumor grade on downloadable tumor slides. Secondly we analyzed the molecular features of each tumor grade group. Our work was performed on a study group of 449 patients. We show that aneuploidy score was significantly different between grade 2 and grade 3 groups with different chromosomal imbalance (p 0.001). SCGB1A1 mRNA expression was higher in grade 2 (p = 0.0179) whereas NUP155, CHFR, POLQ and CDC7 have a higher expression in grade 3 (p = 0.0189, 0.0427, 0.0427 and 0.427 respectively). GZMB and KRT80 have a higher methylation of DNA in grade 2 (p = 0.0201 and 0.0359 respectively). MT1G, CLEC12B and NDUFA7 have a higher methylation of DNA in grade 3 (p 0.001, 0.0246 and 0.0359 respectively). We showed that the number of activated pathways is different between grade 2 and grade 3 patients (p = 0.004). We showed that differentially expressed genes by mRNA analysis and DNA methylation analysis involve several genes implied in chemoresistance. This could suggest that grade 3 lung adenocarcinoma might be more resistant to chemotherapy.

We described for the first time the contrast enhancement of a giant fibrovascular esophageal polyp using ultrasound contrast agent, Sonovue® (Bracco, Milan, Italy) during echoendoscopy. Fine Doppler was unsuccessful in showing vascularization due to the mobile characteristic of the tumor. In contrast, via Sonovue® , tissue microcirculation was highlighted inside the entire head of the polyp, leading to better appreciate the risk of bleeding related to its resection. In a second part, we showed the feasibility of classic polypectomy for this giant polyp (5×5 cm) without complication and results of control endoscopy at 3 months. The present case is summarized in a video.

Highlights • Molecular status determination following decalcification procedures is challenging. • The Idylla™ EGFR assay demonstrates good performance on decalcified bone samples. • The choice of EGFR assay should be adapted to patient and sample specificities., Detection of molecular alterations in lung cancer bone metastasis (LCBM) is particularly difficult when decalcification procedure is needed. The Idylla™ real-time (RT)-PCR is compared to the routine method used in our laboratory, which combines next generation and Sanger sequencing, for the detection of EGFR mutations in LCBM. LCBM subjected to EDTA or formic acid decalcification were analysed for EGFR mutational status using two methods: first, the Ion Torrent Ampliseq next generation sequencing (NGS) assay +/- Sanger sequencing was used prospectively; then, the fully-automated, RT-PCR based molecular testing system Idylla™ EGFR Mutation Test was applied retrospectively. Out of the 34 LCBM assayed, 14 (41.2%) were unsuitable for NGS analysis and five remained unsuitable after additional Sanger EGFR sequencing (5/34, 14.7%). Using Idylla™, valid results were observed for 33/34 samples (97.1%). The concordance between the NGS +/- Sanger sequencing method and the RT-PCR method was 89.7% (26/29), one false positive EGFR S768I mutation and two false negative results were observed using Idylla™; one of these false negative cases was diagnosed by Sanger sequencing with a rare exon 19 EGFR mutation not covered by the Idylla™ EGFR Mutation Test design. Detection of EGFR mutations in decalcified LCBM is challenging using NGS, more than half of samples showing invalid results. Alternative methods should thus be preferred to spare clinical samples and decrease delay. The Idylla™ EGFR Mutation Test shows a good performance on decalcified bone samples and could be used as a first step. In case of negative results, a sequencing approach is mandatory to check the presence of rare EGFR mutations sensitive to EGFR tyrosine kinase inhibitors.

The presence of multiple synchronous lung cancer with the same histopathological type for a patient is a common situation and an issue for staging. Pathological criteria exist to distinguish multiple primaries from intra-pulmonary metastases of the same tumor, but they lack standardization. We wondered how molecular analysis with a limited Next Generation Sequencing panel could bring further information for tumor staging in this setting. We analyzed 24 patients with a total of 50 tumor nodules (22 pairs, two triplets). We compared histopathological examination with molecular analysis. A total of 50 tumors were molecularly tested. Nucleoli size was associated with molecular analysis concordance (p = 0.047). The presence of lepidic component in any of the two larger tumors was associated with molecular analysis concordance (p = 0.012). For molecular analysis, the proportion of progression-free patients was at the limits of significance (p = 0.054) whereas the presence of lepidic component, architectural concordance, and the concordance of comprehensive histologic assessments was not related to progression-free survival. For two patients with a discordant TTF-1 immunohistochemistry, molecular analysis showed a different mutation. Our results show that a limited NGS panel brings supplementary data to classify synchronous lung adenocarcinoma in most patients. We show that molecular staging seems in accordance with progression-free survival. Histopathological examination alone might not be accurate enough to assess a correct staging for synchronous tumors. We also suggest that TTF-1 immunohistochemistry, for the rare discrepant cases, might be a surrogate to molecular analysis.

International audience; 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.

In pleomorphic, spindle cell, and giant cell carcinoma (PSCGC) of the lung, we wondered if an integrated diagnosis including morphological and immunohistochemical features could be related to molecular status. We performed immunohistochemistry on 35 PSCGCs against TTF1, napsin A, p40, ALK, ROS1, and c-MET. Mutational status regarding EGFR, KRAS, BRAF, HER2, and PIK3CA genes was established. Of 18 PSCGCs with adenocarcinomatous or "undifferentiated" carcinoma differentiation, 8 were mutated for EGFR (n = 1), KRAS (n = 2), BRAF (n = 1), HER2 (n = 3), and PIK3CA (n = 1). No PSCGC (0/4) with only squamous cell or adenosquamous (0/2) differentiation was mutated. c-MET overexpression was only seen in PSCGC with adenocarcinomatous or undifferentiated component (n = 5) without squamous cell component. ROS1 and ALK were negative. The presence of a "targetable mutation" was correlated to the presence of morphological or immunohistochemical adenocarcinomatous differentiation (P = .0137). Integrated diagnosis of an adenocarcinomatous component in PSCGC could be associated with the presence of targetable gene mutation. Because only PSCGC with adenocarcinomatous or undifferentiated carcinoma harbors mutations, whereas PSCGC with only squamous or adenosquamous differentiation does not in our study, this might represent a prescreening for patients with PSCGC to be tested for molecular targets. Our results emphasize that careful morphological examination and the use of immunohistochemistry might be useful for the selection of PSCGC tested for a mutational target.

Confocal microscopy is a technique able to realize "optic sections" of a tissue with increasing applications. We wondered if we could apply an ex vivo confocal microscope designed for dermatological purpose in a routine use for the most frequent brain tumors. The aim of this work was to identify tumor tissue and its histopathological hallmarks, and to assess grading criteria used in neuropathological practice without tissue loss on freshly removed brain tissue. Seven infiltrating gliomas, nine meningiomas and three metastases of carcinomas were included. We compared imaging results obtained with the confocal microscope to frozen sections, smears and tissue sections of formalin-fixed tissue. Our results show that ex vivo confocal microscopy imaging can be applied to brain tumors in order to quickly identify tumor tissue without tissue loss. It can differentiate tumors and can assess most of grading criteria. Confocal microscopy could represent a new tool to identify tumor tissue on freshly removed sample and could help in selecting areas for biobanking of tumor tissue.

Introduction: Thymolipoma is a rare benign neoplasm of the anterior mediastinum accounting for 2%-9% of thymic tumors. It mainly consists of adipose tissue comporting foci of thymic tissue. Neoplastic transformation of the epithelial component is extremely rare with four cases of thymoma and a case of thymic carcinoid previously reported. Aim: To report a case of thymolipoma associated with B3 thymoma. Case presentation: A 59 year-old woman treated for asthma presented with dyspnea. No mysthenia gravis was present. Imaging revealed a huge mediastinal tumor of fat density compressing the right lung. Surgical resection revealed a 2.8 kg and 39 cm tumor of mainly lipomatous aspect comporting a stellar solid focus of 3 cm. Microscopically, the tumor was a thymolipoma, with a focus (3 cm) of a B3 thymoma. No complementary treatment was applied and the patient is disease-free, two months after operation. Conclusion: This is the first case of a B3 thymoma arising inside a giant thymolipoma. Diagnosis of thymolipoma should be suspected in a fat-density tumor of the anterior mediastinum. Malignant transformation despite rare is possible and resection is mandatory.

We report the case of a 76-year-old patient presenting with an anterior mediastinal heterogeneous mass. Surgical biopsy revealed a solid and cystic lesion filled with hair. Pathological examination showed an atypical papillary epithelial lining without other germ cell tumor or immature teratoma associated. The final diagnosis was a mature teratoma of the mediastinum with somatic-type malignancy (carcinomatous transformation). After 8-month follow-up, subcutaneous and lymph node metastatic lesions of the carcinomatous component were identified. Subtyping of the malignant component within germ cell tumors is an important challenge for therapeutic options and prognosis.

Meningioma is the most frequent meningeal neoplasm, usually without relapse or metastasis. Patient follow-up is challenging, not standardized and is decided in multidisciplinary case discussion. Our aim was to determine the clinical and histological factors influencing the time to relapse.We conducted a single-Center retrospective study on 38 patients with surgically-excised relapsing meningiomas and collected clinical and pathological data.Our results show that none of the histological factors included in the WHO classification, nor those not included are related to a shorter time to relapse.In our study, none of the histological, immunohistochemical and clinical parameters evaluated seem to be able to predict the time to relapse in meningioma.

Highlights • It is important to differentiate this rare pathological feature of MD from other entities as the treatment is surgical rather than medical. • No pathognomonic clinical symptoms indicating MD has been reported. • Diagnosis usually is by a technetium Tc 99m-pertechnetate scanning. • The treatment of symptomatic MD is surgical resection (wedge resection of the MD or resection of ileum). • The heterotopic tissue is: gastric, pancreatic, jejuna, duodenal, colonic or hepatobiliary tissue., Introduction Intussusception with the Meckel’s diverticulum (MD) is a rare cause of chonic abdominal pain in the adults. We wish to present this first case of intussusception of MD within its own lumen without small bowel obstruction. Presentation of case We report the case of a 27-year-old man who was admitted to the emergency room due to a diffuse abdominal pain. Abdominal CT scan showed invagination of MD. The exploratory laparoscopy revealed the presence of intussusception of MD within its own lumen. Segmental resection of the small intestine was performed. The patient was discharged on the third post-operative day. Discussion The prevalence of MD is 1 to 4%. Diagnosis is often difficult and delayed because clinical symptoms are not specific and the diagnosis is performed mainly by imaging studies. Factors pre-disposing these patients to intussusception of MD within its own lumen include a narrow diverticulum, large diverticululm, and associated inflammation of the diverticulum. Intestinal obstruction is a more common complication in adults, whereas in children, bleeding is the more common complication. In our case, the patient had a diffuse abdominal pain without small bowel obstruction because the intussusception of MD was within its own lumen. Laparoscopy may be useful for confirming the presence of intussusception, and demonstrating the underlying organic lesion serving as the lead point. Conclusion It is important to differentiate this rare pathological feature of MD from other entities as the treatment is surgical rather than medical. Abdominal surgeons should bear in mind this rare entity.