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Background: Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a cancer stem cell (CSC) marker of colorectal cancer and may be a CSC marker of other cancer types. Few studies have been conducted on LGR5 expression in extrahepatic cholangiocarcinoma (ECC). Methods: We analyzed LGR5 expression using RNAscope, a highly sensitive RNA in situ hybridization technique. Fifty-three ECCs were selected from the medical archives at Shinshu University Hospital and analyzed using a tissue microarray. LGR5 expression levels were divided into expression and no expression groups. LGR5 expression and clinicopathological characteristics were analyzed. Results: Among 25 cases, no LGR5-positive dots were identified. Among 28 cases, some LGR5-positive dots were observed in carcinoma cells, together with a wide range of LGR5-positive cells. LGR5 expression was conspicuous in glandular duct formations. Well- to moderately differentiated types showed significantly higher LGR5 expression than the poorly differentiated type (p = 0.0268). LGR5 expression was associated with good overall survival (p = 0.0219) and good disease-free survival (DFS) (p = 0.0228). High LGR5 expression was associated with well- to moderately-differentiated types, indicating a favorable prognosis. In terms of DFS, multivariate analysis showed that high LGR5 expression was an independent favorable prognostic factor (p = 0.0397). Conclusions: These findings suggest that LGR5 is a promising, novel prognostic marker. [ABSTRACT FROM AUTHOR]

CIC-DUX4 sarcoma (CDS) is a recently identified subtype of small round cell sarcoma. Morphologically, CDS partially resembles Ewing sarcoma (ES) and has been classified as "ES-like sarcoma"; however, detailed clinicopathologic and molecular genetic analyses have indicated that CDS is a new independent disease. Many studies have provided light microscopic, immunohistochemical, and genetic information about CDS. However, ultrastructural findings associated with this sarcoma are lacking. The aim of this study was to investigate the ultrastructure of CDS tumors and to compare their features with those of ES. We examined two cytogenetically confirmed CDS cases. We found that, compared to typical ES, CDS presented heterogeneity: in cell density, from tightly packed to loosely unconnected areas; in cell shape, from polygonal to pleomorphic with small processes; and in nuclear shape including round, oval, polygonal, elongated, invaginated, or wrinkled formations. However, abundant glycogen in the cytoplasm and rare cell adhesion apparatus between cells are major similarities between CDS and typical ES. Neuroendocrine granules, which are seen in rare ES cases, could not be identified in these two CDS cases. Although cytogenetic differences can validate a definite diagnosis, ultrastructural features could also provide important information about the differences between CDS and ES. [ABSTRACT FROM AUTHOR]

Here, we report a case of mediastinal mesenchymal tumor with a pericytic neoplasm feature that responded to radiation therapy. A 43‐year‐old man visited our hospital with a complaint of esophageal obstruction and chest pain. Chest computed tomography revealed a middle mediastinal tumor and a mesenchymal tumor was diagnosed with a pericytic neoplasm feature by video‐assisted thoracoscopic biopsy. The definitive treatment for soft tissue tumor is surgical resection; however, the mediastinal tumor was unresectable because of esophageal and tracheal invasion. Radiation therapy was administered and there was a partial tumor response and 2 years disease‐free status. With a review of the literature, we discuss the clinical and pathological characteristics of this rare tumor and its treatment. [ABSTRACT FROM AUTHOR]

Patients with stage I testicular germ cell tumors have a long life expectancy, but the tumors have a potential to relapse after treatment. Although relapse is observed within a few years in most cases, late relapse over 10 years after initial treatment has also been reported in patients with stage I testicular germ cell tumors. We encountered a case of testicular seminoma that developed mediastinal lymph node metastasis 13 years after radical surgery for the primary tumor. The relapsed disease progressed rapidly and the patient died within 1 month due to respiratory failure without any chance for therapy. On postmortem examination, the thoracic lesions were pathologically confirmed to be metastases from the testicular seminoma with yolk sac tumor. Here, we report the clinical course and a review of the relevant literature. Based on our experience, we emphasize long-term follow-up and/or careful examination in patients with stage I testicular germ cell tumors. [ABSTRACT FROM AUTHOR]