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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gingival tumor that invaded the anterior maxilla was removed from a 14-year-old boy and studied by light and electron microscopy. The tumor was composed exclusively of myoepithelial cells and appeared to be malignant. By light microscopy, the tumor appeared to be a poorly differentiated epithelial neoplasm of undetermined origin; however, electron microscopical examination showed myoepithelial differentiation, indicative of a salivary gland origin. To our knowledge, the present case represents the only confirmed myoepithelioma that shows features indicative of malignant potential. Myoepitheliomas may be related to mixed tumors of salivary glands.
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PMID:Myoepithelioma of minor salivary gland origin. Light and electron microscopical study. 4 74

Two cases of adenomatoid odontogenic tumor were examined by light and electron microscopy. Morphologically the tumors could be divided into four layers. The ultrastructure of the tumor cells of each layer was revealed to be similar respectively to that of four layers seen in the enamel organ of a normal tooth germ. Duct-like structures and eosinophilic small areas were frequently present in compactly proliferating cell layers. Short columnar cells forming duct-like structures and eosinophilic small areas appeared similar ultrastructurally to ameloblasts during predentin formation. Therefore it seems reasonable to assume that this tumor originates from the enamel organ. The contents in the lumen of each eosinophilic small area varied, and seemed to be secreted into the stroma by circumscribing epithelial tumor cells. A fine filamentous layer was present in both of the duct-like structures and some of the eosinophilic small areas, and the former was different from the latter with respect to the alcian blue (pH 2.5) and toluidine blue (pH 4.4) staining reactions.
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PMID:Ultrastructural study of adenomatoid odontogenic tumor. 8 12

A first case of genuine neoplasm is reported in the order Araneida. This epithelial tumor, proceeding from oviduct ends, invades uterus; malignancy is strongly supported by cell structure and extensive local behavior.
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PMID:[A malignant tumour in the female genital tract of Pachygnatha clercki Sundevall, 1823 (Arachnida, Araneae, Tetragnathidae)]. 10 Feb 55

The application of biochemical studies for the detection of Epstein-Barr virus (EBV)-DNA in human tumor cells is discussed. These studies resulted in the consistent demonstration of viral nucleic acid in African Burkitt's lymphoma biopsies and in epithelial tumor cells of nasopharyngeal carcinomas. The viral DNA resides within those cells regularly in multiple copies per cell. Besides these tumors our group detected significant concentrations of EBV-DNA in a German lymphoma patient revealing histological characteristics of Burkitt's lymphoma. Moreover, virus DNA was also found in a patient suffering from immunoblastic lymphadenopathy. More than 50 additional B-cell lymphomas and more than 40 biopsies from patients with Hodgkin's disease did not contain detectable amounts of EBV-DNA when tested by nucleic acid hybridization. A tentative scheme of EBV-induced pathogenesis is discussed.
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PMID:Biochemical approaches to detection of Epstein-Barr virus in human tumors. 17 25

Electron microscopy examination of nasopharyngeal carcinoma grafts in nude mice showed that the tumor cells retained their epithelial characteristics, as betrayed by the presence of keratin fibrils and of functional complexes at the cell membrane. Thus the cells positive for Epstein-Barr virus-specific nuclear antigen present in such grafts do represent the progeny of human epithelial tumor cells. C-type virus particles were observed in one tumor graft, indicating that epithelial human cells could pick up a mouse virus.
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PMID:Epithelial characteristics of tumor cells in nasophasyngeal carcinoma. 18 91

A case of a malignant epithelial tumor of tail of the pancreas in a 3-year-old Japanese girl is presented. This is the fourth case reported with ultrastructural study. This type of pancreatic carcinoma of the infant has no endocrine granules or endocrine function. The ultrastructural study suggests that the tumor is derived from a primitive epithelial cell with differentiation toward acinar cell.
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PMID:Pancreatic carcinoma in infancy. An electron microscopic study. 18 66

Lung carcinoma of sheep (Jaagsiekte) is a bronchiolar-alveolar cell carcinoma. Differences in the ultrastructural patterns of early and advanced lesions of the disease are described. A-type and C-type viruses were observed in advanced tumors and were absent in early lesions. Numerous microtubules were characteristic in the epithelial tumor cells of the early lesions and were absent in the advanced tumor. In comparison to the early lesions, extensive cytosome production, surfactant secretion, and glycogen accumulation were observed in the advanced tumor. The immune response to the early tumor lesion was restricted to the peribronchiolar lymph aggregates, while in the advanced stages of the disease the systemic immune response was markedly increased.
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PMID:Pulmonary carcinoma (Jaagsiekte) of sheep. Ultrastructural study of early and advanced tumor lesions. 19 Aug 91

Erytrophagocytosis by epithelial tumor cells has been observed in metastases of ductal carcinoma of the female breast. Some malignant cells of this tumor seem to be capable of phagocytizing and digesting extravasated red blood cells with for formation of residual hemosiderin probably from their hemoglobin content. Erythrophagocytosis has been observed only in hemorrhagic areas of the tumor. Erythrophagocytosis has been observed only in hemorrhagic areas of the tumor. Although the nature of this phenomenon is unknown, it is postulated that acquired hematological disturbancess during the natural course of the malignant disease affect the surface of the red blood cells making them vulnerable to phagocytosis by the malignant cells. This case seems to represent the second time such a phenomenon has been reported in an epithelial neoplasm in man. However, it has been more frequently observed in reticulo-endothelial malignancies. The possible occurence of this phenomenon should alert pathologists to search for it in primary and metastatic epithelial tumors and in living patients to correlate pertinent hematological studies in an attempt to elucidate its possible significance.
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PMID:Erythrophagocytosis by epithelial cells of a breast carcinoma. 19 42

Saliva samples from 59 patients with nasopharyngeal carcinoma (NPC) and from 20 normal individuals were studied to determine the nature and origin of the EBV-specific IgA in NPC saliva. About 50% of NPC saliva samples contained secretory IgA specific for EBV. The corresponding tumor IgA(alpha) was found in plasma cells surrounding the epithelial tumor cells and the secretory piece at the surface of epithelial cells. A slightly higher proportion of NPC saliva samples containing IgA was found in patients from Tunis than in samples from Hong Kong. Attention is drawn to the clinical value of the salivary IgA in diagnosis and monitoring of treatment of NPC.
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PMID:EBV specific secretory IgA in saliva of NPC patients. Presence of secretory piece in epithelial malignant cells. 20 74

Amyloid as defined by positive Congo red green birefringence and STB red birefringence was observed in the stroma of a tubular carcinoma of minor salivary gland origin. The amyloid exhibited additional histochemical characteristics of immunamyloid, viz., positive DMAB-nitrate and DC-reactions and spontaneous autofluorescence. Electron microscopic studies of the epithelial tumor cells displayed large amounts of cytoplasmic microfilaments similar to those present in the extracellular amyloid masses. It is suggested that the amyloid is derived from spontaneous assembly or polymerization of cytoplasmic microfibrils of the dying tumor cells as has been proposed for the amyloid associated with the calcifying epithelial odontogenic tumor (CEOT).
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PMID:Amyloid stroma in a tubular carcinoma of palatal salivary gland: a histochemical and ultrastructural study. 20 40


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