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

The report describes a malignant gastrointestinal stromal tumor occurring in the duodenum in a 71-year-old woman. The neoplasm showed both epithelioid and spindle cell patterns by light microscopy. The ultrastructural features were diagnostic of nerve sheath origin. The tumor had numerous wrapping processes joined by junctions and surrounded by axons. No features of smooth muscle differentiation were identified. Immunocytochemistry was inconclusive. The differential diagnosis of such neoplasms is discussed.
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PMID:Gastrointestinal stromal tumor of the duodenum: a case report. 175 8

A gastrointestinal stromal tumor, arising from the rectal ampulla of a 63-yr-old man, was investigated using conventional techniques as well as Western blot analysis of its cytoskeleton proteins. The expression of desmin, muscle-specific actins, vimentin, S-100 protein, chromogranin, neuron-specific enolase, and keratins was studied using the avidin-biotin technique. The tumor cells showed a positive reaction only to antivimentin antibody. Ultrastructural analysis failed to provide conclusive evidence for neural or muscular origin of the tumor. Western blot analysis of the tumor whole-protein extract allowed identification of the presence of gamma-smooth-muscle actin, thus suggesting an enteric smooth-muscle origin of the tumor. This result seems partially to support a parenchymal smooth-muscle origin for S-100 protein and desmin-negative gastrointestinal tumors.
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PMID:Gastrointestinal stromal tumor: evidence for a smooth-muscle origin. 777 83

Nine cases are presented of a distinctive morphologic variant of myogenic gastrointestinal stromal tumor characterized by an unusually prominent myxoid stromal background reminiscent of a neural neoplasm but lacking the immunohistochemical or ultrastructural features of peripheral nerve sheath or ganglionic differentiation. The patients included six women and three men aged 42 to 86 years (mean, 70). The lesions occurred in the stomach (seven cases) and small intestine (two cases) and ranged in size from 2.5 to 9.5 cm. They were described grossly as well circumscribed, unencapsulated, with a prominently myxoid and often cystic cut surface. Histologically, the lesions were composed of a proliferation of round, spindle, or stellate cells embedded in an abundant myxoid stroma. Histochemical stains showed strong positive reaction of the myxoid stromal background with alcian blue at pH 2.5; this staining reaction was abolished by treatment with hyaluronidase, indicating an abundance of connective tissue mucosubstances rich in hyaluronic acid. Immunohistochemical stains showed strong positivity of the tumor cells with vimentin antibodies in all cases and focal weak to moderate positive staining with muscle actin (HHF35) in eight cases and with desmin in two. Stains for keratin, S-100; epithelial membrane antigen, and collagen type IV were uniformly negative. Ultrastructural examination carried out in all cases showed features consistent with those previously described for myogenic gastrointestinal stromal tumors, namely, scattered mitochondria and prominent Golgi apparati, strands of rough endoplasmic reticulum, focal accumulation of intracytoplasmic microfilaments with occasional focal condensations, subplasmalemmal attachment plaques and immature cell junctions, focal extracellular basal lamina material, and surface-oriented micropinocytotic activity. The myxoid changes observed in these tumors may represent a secondary, nonspecific reaction pattern of the tumor cells to some noxious stimulus, or they may be a form of degenerative phenomenon such as that commonly observed in smooth-muscle tumors of the uterus and other sites. Myogenic gastrointestinal stromal tumors with prominent myxoid stroma should be distinguished from benign schwannoma of the stomach and gastrointestinal autonomic nerve tumors. Because of the differences in prognosis for these entities, immunohistochemical and ultrastructural examinations are recommended for the evaluation of gastrointestinal stromal neoplasms with prominent myxoid features.
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PMID:Gastrointestinal stromal tumors with prominent myxoid matrix. Clinicopathologic, immunohistochemical, and ultrastructural study of nine cases of a distinctive morphologic variant of myogenic stromal tumor. 750 67

Gastric tumors discovered during pregnancy are rare. A cystic gastric stromal tumor with adjacent peritoneal nodules and associated with ascites was encountered in a 32-year-old pregnant patient. On initial clinical evaluation the mass was thought to originate from the uterine adnexa. The tumor itself was composed of uniform spindle cells with minimal mitotic activity. Immunohistochemical and ultrastructural studies were consistent with a gastrointestinal stromal tumor (GIST). Small nodules on the gastric serosa and adjacent omentum resembled those of leiomyomatosis peritonealis disseminata but were confined to the upper abdomen and on further study lacked evidence of smooth muscle differentiation. Although many of these nodules were not resected, a CT scans 3 and 9 months later failed to detect them. This case of GIST in pregnancy is apparently unique and distinct from leiomyomatosis peritonealis disseminata and rare forms of intestinal leiomyomatosis.
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PMID:Gastric stromal tumor with peritoneal nodules in pregnancy: tumor spread or rare variant of diffuse leiomyomatosis. 894 78

Gastrointestinal autonomic nerve tumor (GANT) is a specialized form of stromal neoplasm whose ultrastructural features support a myenteric plexus derivation and provide the basis for its diagnosis. GANT actual frequency, relationship to skeinoid fibers, and CD34 expression status are some of the controversial aspects of this entity. Out of 14 gastrointestinal stromal tumors gathered during a 1-year period, six (42%) instances were diagnosed as GANT by electron microscopic study of at least five ultrathin sections per case. Additionally, GANTs were immunohistochemically investigated with a panel of nine antibodies including CD34. Ultrastructurally, every GANT case showed diagnostic findings and evidence of skeinoid fibers, whereas immunohistochemically all except one were CD34 positive. Immunoreactivity for neuron-specific enolase, synaptophysin, and vimentin was a common occurrence as well. In conclusion, GANT seems to be more frequent than hitherto recognized, skenoid fibers are a regular feature of GANT, and a positive CD34 immunoreaction does not discriminate between GANT and other non-smooth muscle, non-schwannian neoplasms.
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PMID:Gastrointestinal autonomic nerve tumor: further observations regarding an ultrastructural and immunohistochemical analysis of six cases. 895 4

Smooth muscle tumors of the alimentary tract are uncommon. A retrospective study was made of 7 patients treated for leiomyosarcoma of the small and large bowel to identify prognostic factors that influence results. The symptoms associated with these tumors varied according to the anatomic sites of the lesions and the position of the growth in relation to the intestinal lumen but the most common presenting clinical signs are bleeding or obstruction. The differential diagnosis between benign and malignant smooth muscle tumors is sometimes quite difficult. Clinical behavior of the myosarcomas of the gastrointestinal tract can be predicted to a large extent by the site of the tumor, the presence or absence of invasion of adjacent vital organs, and the histopathologic grade of malignancy. Although the mitotic activity of a gastrointestinal stromal tumor remains the most critical prognostic factor, tumors have been seen to recur locally and to metastasize even with rare or absent mitotic figures. Further studies are needed to pinpoint the factors that may be correlated to the prognosis.
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PMID:[Leiomyosarcoma of the small intestine and the colorectum. A case contribution]. 908 27

The gastrointestinal autonomic nerve tumor (GAN tumor) is an uncommon stromal tumor with a morphological feature resembling the cell processes of the enteric plexus, and was originally termed a plexoma or plexosarcoma. Light microscopic studies show the GAN tumor most often consists of spindle-shaped cells indistinguishable from a smooth muscle tumor or Schwann cell tumor. Immunohistochemical and ultrastructural examinations of 18 cases of gastrointestinal stromal tumor (GIST) were performed. During ultrastructural examination, all of the 12 cases which were immunohistochemically positive for S-100 protein or neuron-specific enolase (NSE) showed synapse-like structures containing dense core neurosecretory granules measuring 100-200 nm, and 40-60 nm endocytoplasmic vesicles. These results suggest that most GIST of neurogenic origin are tumors derived from the myenteric nerve plexus.
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PMID:Gastrointestinal autonomic nerve tumors: immunohistochemical and ultrastructural studies in cases of gastrointestinal stromal tumor. 914 26

We report a case of gastrointestinal stromal tumor (GIST) of the stomach. The patient was a 79-year-old woman with two gastric submucosal tumors detected by ultrasonography. Proximal gastrectomy was carried out and the tumors were diagnosed as GIST by histological and immunohistochemical investigations. Mesenchymal tumors of the gastrointestinal tract have been traditionally regarded as largely leiomyomatous lesions. However, GIST and other tumors have been distinguished recently on the basis of tumor cell differentiation shown by immunohistochemical studies. We discuss the concept and the immunohistochemical characteristics of GIST.
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PMID:Gastrointestinal stromal tumor of the stomach. 921 84

Neoplasms of the small intestine are very rare. Gastrointestinal stromal tumors (GISTs) are one of the new undifferentiated stromal tumors of the gastrointestinal tract diagnosed by immunohistochemistry. We present a case of a malignant GIST arising from the small intestine and report the radiologic characteristics of the tumor and pathological correlation. CT showed a very large, enhancing mass with extensive central necrosis located on the mesenteric side of the jejunum. A perforation into the jejunal lumen was observed by upper GI series. MRI showed a very large tumor which was hypointense on T2-weighted images. Ultrasound revealed a mixed solid and cystic mass. Grossly, the tumor was solid peripherally with extensive central necrosis. Microscopically, it consisted of spindle and epithelioid cells. Immunohistochemically, the cells stained positive for CD34, which is diagnostic of GIST.
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PMID:Malignant gastrointestinal stromal tumor of the small intestine: radiologic-pathologic correlation. 927 78

A unique case of duodenal stromal tumor in a 51-year-old man is reported. The tumor histologically showed spindle cell proliferation and numerous eosinophilic globules. Most globules were composed of tangled 45 nm thick fibrils, which were ultrastructurally identical to 'skeinoid fibers'. The presence of glycogen granules in the tumor cells and the immunoreactivity for alpha-smooth muscle actin suggested smooth muscle differentiation. Focal ultrastructural findings also supported the smooth muscle nature of this tumor. There were no immunohistochemical and ultrastructural features indicating neural differentiation. In previous studies, the presence of such 'skeinoid fibers' was suggested to be a histological marker for neural differentiation in gastrointestinal stromal tumor. However, the findings in the present case suggest that numerous 'skeinoid fibers' can be identified in duodenal stromal tumor with smooth muscle differentiation, although this condition may be rare.
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PMID:Numerous eosinophilic globules (skeinoid fibers) in a duodenal stromal tumor: an exceptional case showing smooth muscle differentiation. 941 40


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