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Pulmonary neuroendocrine (NE) cells are rare airway epithelial cells. The balance between Achaete‐scute complex homolog 1 (ASCL1) and hairy and enhancer of split 1, one of the target molecules of the Notch signaling pathway, is crucial for NE differentiation. Small cell lung cancer (SCLC) is a highly aggressive lung tumor, characterized by rapid cell proliferation, a high metastatic potential, and the acquisition of resistance to treatment. The subtypes of SCLC are defined by the expression status of NE cell‐lineage transcription factors, such as ASCL1, which roles are supported by SRY‐box 2, insulinoma‐associated protein 1, NK2 homeobox 1, and wingless‐related integration site signaling. This network reinforces NE differentiation and may induce the characteristic morphology and chemosensitivity of SCLC. Notch signaling mediates cell‐fate decisions, resulting in an NE to non‐NE fate switch. The suppression of NE differentiation may change the histological type of SCLC to a non‐SCLC morphology. In SCLC with NE differentiation, Notch signaling is typically inactive and genetically or epigenetically regulated. However, Notch signaling may be activated after chemotherapy, and, in concert with Yes‐associated protein signaling and RE1‐silencing transcription factor, suppresses NE differentiation, producing intratumor heterogeneity and chemoresistance. Accumulated information on the molecular mechanisms of SCLC will contribute to further advances in the control of this recalcitrant cancer. [ABSTRACT FROM AUTHOR]

Solid papillary carcinoma (SPC) is a histological subtype of breast carcinomas. At least 50% of SPC show neuroendocrine differentiation. Insulinoma‐associated protein 1 (INSM1) is a transcription factor now employed as a useful neuroendocrine marker. It is suppressed by the Notch signaling pathway in other neuroendocrine tumors. However, the usefulness of INSM1 as a neuroendocrine marker and the relationships between INSM1 and NOTCH receptors in SPC of the breast currently remain unclear. To clarify the usefulness of INSM1 as a neuroendocrine marker and the relationships between INSM1 and NOTCH receptors in SPC, we performed immunohistochemistry using 19 tissue specimens of SPC of the breast. We complementarily analyzed public RNA sequencing data on breast carcinomas. Immunohistochemical examinations revealed that the staining intensity of INSM1 was significantly higher in the neuroendocrine group than in the non‐neuroendocrine group. Positive correlations were observed between INSM1 and synaptophysin (SYP), or chromogranin‐A (CHGA). In all cases, NOTCH 2 and 3 were positive, while NOTCH 1 and 4 were negative. According to public RNA data analyses, there were positive correlations between INSM1 and SYP, or CHGA, and negative correlations between INSM1 and NOTCH1–3. INSM1 is useful as a diagnostic marker for SPC with neuroendocrine differentiation in the breast. [ABSTRACT FROM AUTHOR]

Reported herein is a 57-year-old man infected by Sparganum mansoni, a kind of tapeworm, showing a solitary nodule of the middle lobe of the right lung. Because a transbronchial biopsy could not diagnose the nodule, a right middle lobectomy was performed on suspicion of malignant tumor. The lesion was diagnosed as sparganosis by histological and immuno-serological examinations. Histological examination revealed granulomatous inflammation with neutrophil and eosinophil infiltration around the worm and interstitial pneumonia surrounding the nodule. Moreover, vasculitis with foreign body giant cell was seen around the lesion. To the authors' knowledge this is the second case of sparganosis limited in the lung, and the current report presents the first detailed histological description of a pulmonary sparganosis case. [ABSTRACT FROM AUTHOR]

We report an extremely rare case of primary lung cancer showing various histological elements diagnosed as the collision of an adenosquamous carcinoma and a large cell neuroendocrine carcinoma by loss of heterozygosity (LOH) analysis of the human androgen receptor (AR) and phosphoglycerate kinase (PGK-1) genes. The tumor exhibited a tiny ground-glass opaque shadow suggesting atypical adenomatous hyperplasia 18 months prior to surgery. However, the tumor grew rapidly, and the resected tumor consisted of two closely located nodules. The larger nodule was composed of well-differentiated adenocarcinomatous and moderately to poorly differentiated squamous cell carcinomatous elements, while the smaller nodule consisted of a large cell neuroendocrine carcinomatous element with partial squamoid differentiation having focal continuity with the adenocarcinomatous element. Both the adenocarcinomatous and squamous cell carcinomatous elements revealed transitional features and LOH of AR and PGK-1 genes, while the large cell neuroendocrine carcinomatous element showed a monoclonal pattern but possessed both alleles of AR and PGK-1 genes. From these clinical and pathological results, the parental cell of the large cell neuroendocrine carcinomatous element was considered to be different from that of the adenosquamous carcinomatous element. [ABSTRACT FROM AUTHOR]

Myoepithelioma of the lacrimal gland is extremely rare and only four cases, one of which was malignant, have been reported in detail. The present report describes a case of lacrimal gland myoepithelioma in a Japanese male with histological features suggestive of potentially malignant transformation. The excised tumor consisted of two components, a central nodular component and a peripheral component surrounding the former. These components were separated by a fibrous tissue. Microscopically, both components were comprised almost entirely of spindle-shaped cells, but with some epithelioid cells containing glycogen granules. Extracellular spaces in the peripheral component were filled with eosinophilic materials with the occasional crystalloid structures, which were immunoreactive for collagen type I. Neoplastic cells were immunoreactive focally for vimentin and S-100, but negative for cytokeratins, epithelial membrane antigen, muscle actin, smooth muscle actin, desmin, myosin, and glial fibrillary acidic protein. The neoplastic cells in the central component showed nuclear pleomorphism and atypia with a higher frequency of mitotic figures, and higher labelings of proliferation markers than those in the peripheral component. Neither invasion, necrosis, nor hemorrhage was observed in the tumor. From these findings we proposed a diagnosis of potentially malignant myoepithelioma. [ABSTRACT FROM AUTHOR]

Elucidates the incidence of histiocytoid breast carcinoma (HBC) in Japan. Review of histological specimen from breast cancer patients; Foci of in situ lobular carcinoma in cases of pure HBC; Presence of targetoid and Indian file invasive patterns in all cases of pure HBC.