Pulmonary arteriovenous malformations (PAVMs) are vascular anomalies resulting in abnormal connections between pulmonary arteries and veins. In 80% of cases, PAVMs are present from birth, but clinical manifestations are rarely seen in childhood. These congenital malformations are typically associated with Hereditary Hemorrhagic Telangiectasia (HHT), a rare disease that affects 1 in 5000/8000 individuals. HHT disease is frequently caused by mutations in genes involved in the TGF-β pathway. However, approximately 15% of patients do not have a genetic diagnosis and, among the genetically diagnosed, more than 33% do not meet the Curaçao criteria. This makes clinical diagnosis even more challenging in the pediatric age group. Here, we introduce an 8-year-old patient bearing a severe phenotype of multiple diffuse PAVMs caused by an unknown mutation which ended in lung transplantation. Phenotypically, the case under study follows a molecular pattern which is HHT-like. Therefore, molecular- biological and cellular-functional analyses have been performed in primary endothelial cells (ECs) isolated from the explanted lung. The findings revealed a loss of functionality in lung endothelial tissue and a stimulation of endothelial-to-mesenchymal transition. Understanding the molecular basis of this transition could potentially offer new therapeutic strategies to delay lung transplantation in severe cases.

BACKGROUND: Metastatic cardiac tumors are known to occur more frequently than primary cardiac tumors, however, they often remain asymptomatic and are commonly discovered on autopsy. Malignant tumors with a relatively high frequency of cardiac metastasis include mesothelioma, melanoma, lung cancer, and breast cancer, whereas reports of esophageal cancer with cardiac metastasis are rare.
METHODS: The case of a 60-year-old man who complained of dysphagia is presented. Upper gastrointestinal endoscopy showed a submucosal tumor-like elevated lesion in the esophagus causing stenosis. Contrast-enhanced computed tomography showed left atrial compression due to the esophageal tumor, multiple liver and lung metastases, and a left pleural effusion. Pathological examination of a biopsy specimen from the esophageal tumor showed spindle-shaped cells, raising suspicion of esophageal sarcoma. The disease progressed rapidly, and systemic chemotherapy was deemed necessary, however, due to his poor general condition, administration of cytotoxic agents was considered difficult. Given his high Combined Positive Score, nivolumab was administered, however, the patient soon died from the disease. The autopsy confirmed spindle cell carcinoma (SCC) of the esophagus and cardiac metastasis with similar histological features. Cancer stem cell markers, ZEB1 and TWIST, were positive in both the primary tumor and the cardiac metastasis.
CONCLUSIONS: To the best of our knowledge, there have been no prior reports of cardiac metastasis of esophageal SCC. This case highlights our experience with a patient with esophageal SCC who progressed rapidly and died from the disease, with the autopsy examination showing cardiac metastasis.

Follicular thyroid carcinoma (FTC) is recognized by its ability to invade the tumor capsule and blood vessels, although the exact molecular signals orchestrating this phenotype remain elusive. In this study, the spatial transcriptional landscape of an FTC is detailed with comparisons between the invasive front and histologically indolent central core tumor areas. The Visium spatial gene expression platform allowed us to interrogate and visualize the whole transcriptome in 2D across formalin-fixated paraffin-embedded (FFPE) tissue sections. Four different 6 × 6 mm areas of an FTC were scrutinized, including regions with capsular and vascular invasion, capsule-near area without invasion, and a central core area of the tumor. Following successful capturing and sequencing, several expressional clusters were identified with regional variation. Most notably, invasive tumor cell clusters were significantly over-expressing genes associated with pathways interacting with the extracellular matrix (ECM) remodeling and epithelial-to-mesenchymal transition (EMT). Subsets of these genes (POSTN and DPYSL3) were additionally validated using immunohistochemistry in an independent cohort of follicular thyroid tumors showing a clear gradient pattern from the core to the periphery of the tumor. Moreover, the reconstruction of the evolutionary tree identified the invasive clones as late events in follicular thyroid tumorigenesis. To our knowledge, this is one of the first 2D global transcriptional mappings of FTC using this platform to date. Invasive FTC clones develop in a stepwise fashion and display significant dysregulation of genes associated with the ECM and EMT - thus highlighting important molecular crosstalk for further investigations.

Mesenchymal-epithelial transition (MET) exon 14-skipping mutation (METex14) is rare in pulmonary invasive mucinous adenocarcinomas (IMAs), and the clinical impact of MET-tyrosine kinase inhibitors (TKIs) remains unknown. We herein report a 75-year-old woman with IMA harboring METex14 who was treated with the MET-TKI tepotinib. The lung tumor regressed over six months; however, the patient ultimately died of exacerbated interstitial lung disease (ILD), possibly associated with tepotinib. An autopsy revealed diffuse alveolar damage in pre-existing chronic fibrosis. We discuss how to pre-evaluate ILD deterioration risks and monitor TKI-induced lung toxicity during treatment.

The signet-ring cell variant of squamous cell carcinoma (SCC) is an extremely rare histological subtype, with only 24 cases (including the present case) reported in the Medline database: 15 affecting the external surface of the body, 3 in the lung, 2 affecting the uterine cervix, 1 involving the gingiva, another one affecting the esophagus and the present case that is the first reported at the gastro-esophageal junction (GEJ). In one case, the location of the lesion was not mentioned. A 59-year-old male patient underwent segmental eso-gastrectomy for carcinoma of the GEJ. The microscopic examination showed a pT3N1-staged SCC composed of solid nests admixed in over 30% of the tumor, with cells having eccentrically located nuclei and clear vacuolated cytoplasm. The signet-ring cells did not show mucinous secretion and were positive for keratin 5/6 and vimentin, with nuclear expression of β-catenin and Sox2 and focal membrane positivity for E-cadherin. Based on these features, the case was considered a signet-ring SCC with epithelial-mesenchymal transition. Thirty-one months after surgery, the patient was disease-free, with no local recurrence and no known distant metastases. In SCC, a signet-ring cell component might be an indicator of the dedifferentiation of tumor cells towards a mesenchymal molecular subtype.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rare cancer, and in 80% of cases the cause is asbestos exposure. In 1972, the World Health Organization (WHO) declared asbestos is a carcinogenic substance. Since then, every developed country has restricted and banned the product. Because of its high heat resistance, asbestos had been widely used as building material for decades. The WHO estimated that approximately 125 million people are exposed to asbestos, and more than 107,000 die from asbestos-related diseases annually. Because of its long incubation period, the number of patients is estimated to keep increasing in the near future.
METHODS: The authors report a case of long-surviving MPM with a rushed clinical course after brain metastasis. A 69-year-old woman diagnosed with MPM (epithelial type) 6 years earlier presented with a brain metastasis. The pathological result of the brain metastasis was the sarcomatoid type. This case showed the possibility of subtype transition after long survival.
CONCLUSIONS: This article aids in understanding the long-term natural history of MPM and the possibility of epithelial-mesenchymal transition. Neurosurgeons have to be aware of its the natural history and the possibility of brain metastasis.

Malignant transformation in leiomyoma is rare, with a few documented cases of sarcomatous transformation in leiomyomas. However, carcinosarcomatous transformation in leiomyomas is extremely infrequent. A 45-year-old female presented with a mass sensation per abdomen for the last five months. An abdominal ultrasound revealed multiple uterine fibroids. Contrast-enhanced magnetic resonance imaging revealed a large multiloculated abdominopelvic mass arising from the fundus of the uterus, along with multiple smaller subserosal fibroids. A total abdominal hysterectomy with bilateral salpingectomy was performed. Grossly, the uterus was bosselated with multiple subserosal fibroids. The larger degenerated fibroid showed a smooth outer surface; however, the cut surface was predominantly cystic and filled with necrotic material. Microscopically and immunohistochemically, the larger mass showed a high-grade biphasic tumor comprising carcinomatous and sarcomatous components with the peripheral solid areas showing compressed smooth muscle bundles representing the residual leiomyomatous areas. A final diagnosis of carcinosarcomatous transformation in leiomyoma was rendered. The index report highlights the significance of systematic gross and microscopic examination of all the uterine masses in patients with multiple leiomyomata.

It has been proposed that epithelial-mesenchymal transition (EMT) is responsible for the pathogenesis of several diseases. However, the relationship between the EMT process and the severity of periodontitis has not been previously investigated.
This study aimed to localize and quantitatively assess the expression of transforming growth factor-beta 1 (TGF-β1), vimentin and E-cadherin in correlation with the EMT process in human gingiva of periodontally diseased patients in comparison with halthy individuals.
Gingival tissue samples from 36 participants were divided into 2 groups: the healthy (control) group (n = 9); and the periodontitis group (n = 27). The periodontitis group was further subclassified into mild, moderate and severe periodontitis subgroups (9 patients in each subgroup). The samples were subjected to histological staining, the histomorphometric analysis and the quantitative real-time polymerase chain reaction (RT‑PCR) analysis for TGF-β, vimentin and E-catherin. Statistical and correlation analyses were performed.
The hematoxylin and eosin (H&E) stain sections from both the moderate and severe periodontitis subgroups showed epithelial hyperplasia, perinuclear haloing and a marked increase in the inflammatory cell count as compared to the control group. The highest mean TGF-β1 and vimentin expression values were recorded in the severe periodontitis subgroup, whereas the lowest mean values were recorded in the control gingiva. On the contrary, the expression of E-catherin had the highest mean value in the control gingiva, whereas the lowest mean value was recorded in the severe periodontitis subgroup. All results were found to be statistically significant. The correlation analysis revealed a statistically significant positive correlation between the severity of periodontitis and the expression of TGF-β and vimentin, while a statistically significant inverse correlation was found between the expression of E-catherin and the severity of periodontitis.
There is a direct correlation between the severity of periodontitis and the expression of the EMT process markers (TGF-β and vimentin). This correlation indicates that EMT plays an important role in the pathogenesis and prognosis of periodontal disease. The data presented in this study could open the door for using anti-EMT agents in treating periodontal disease.

BACKGROUND: Gliosarcoma (GS) refers to the presence of mesenchymal differentiation (as seen using light microscopy) in the setting of glioblastoma (GB, an astrocytoma, WHO Grade 4). Although the same approach to treatment is typically adopted for GS and GB, there remains some debate as to whether GS should be considered a discrete pathological entity. Differences between these tumors have not been clearly established at the molecular level.
METHODS: Patients with GS (n=48) or GB (n=1229) underwent molecular profiling (MP) with a pan-cancer panel of tests as part of their clinical care. The methods employed included next-generation sequencing (NGS) of DNA and RNA, copy number variation (CNV) of DNA and immunohistochemistry (IHC). The MP comprised 1153 tests in total, although results for each test were not available for every tumor profiled. We analyzed this data retrospectively in order to determine if our results were in keeping with what is known about the pathogenesis of GS by contrast with GB. We also sought novel associations between the MP and GS vs. GB which might improve our understanding of pathogenesis of GS.
RESULTS: Potentially meaningful associations (p<0.1, Fisher\'s exact test (FET)) were found for 14 of these tests in GS vs. GB. A novel finding was higher levels of proteins mediating immuno-evasion (PD-1, PD-L1) in GS. All of the differences we observed have been associated with epithelial-to-mesenchymal transition (EMT) in other tumor types. Many of the changes we saw in GS are novel in the setting of glial tumors, including copy number amplification in LYL1 and mutations in PTPN11.
CONCLUSIONS: GS shows certain characteristics of EMT, by contrast with GB. Treatments targeting immuno-evasion may be of greater therapeutic value in GS relative to GB.

BACKGROUND: Neuroendocrine neoplasms (NENs) are a complex group of tumours that occur in many organs. Routinely used IHC markers for NEN diagnosis include CgA, synaptophysin, Ki67 and CD56. These have limitations including lack of correlation to clinical outcomes and their presence in non-tumour tissue. Identification of additional markers and more quantitative analyses of tumour tissue has the potential to contribute to improved clinical outcomes. We used qRT-PCR to profile the expression levels of a panel of markers in tumour and matched non-tumour tissue from a patient with a G1 pancreatic neuroendocrine tumour. Differences in mRNA levels between tumour and non-tumour tissue were compared with IHC analyses of the same sample.
METHODS: An elderly man presented with lower abdominal pain for 6 months. Histological analysis identified a low grade, well differentiated pancreatic endocrine neoplasm. Twenty-seven tumour markers for neuroendocrine status, proliferation, stem cell phenotype, angiogenesis, epithelial to mesenchymal transition, cell adhesion, differentiation and tumour suppression were selected from previous studies and mRNA levels of these markers were measured in tumour and adjacent non-tumour tissue sample using qRT-PCR. IHC was carried out on the same tissue to detect the corresponding marker proteins. Of the markers analysed, seven showed higher mRNA levels in tumour relative to non-tumour tissue while thirteen had lower expression in tumour relative to non-tumour tissue. Substantial differences in mRNA levels were a gain of CgA, CD56, β-catenin, CK20, PDX1 and p53 and loss of Ki67, PCAD, CK7, CD31, MENA, ECAD, EPCAM, CDX2 and CK6. Comparison of qRT-PCR data with IHC showed correlation between fifteen markers.
CONCLUSIONS: Our study is unique as it included matched controls that provided a comparative assessment for tumour tissue analysis, whereas many previous studies report tumour data only. Additionally, we utilised qRT-PCR, a relatively quantitative diagnostic tool for differential marker profiling, having the advantage of being reproducible, fast, cheap and accurate. qRT-PCR has the potential to improve the defining of tumour phenotypes and, in combination with IHC may have clinical utility towards improving tumour stratification or distinguishing tumour grades. The results need to be validated with different grades of NENs and related to clinical outcomes.