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

Gastrointestinal stromal tumors (GISTs) represent an enigmatic group of lesions of uncertain phenotype and biologic potential. Although earlier studies suggested smooth muscle cells, schwann cells, or neuronal differentiation, more recent evidence indicates that these tumors show phenotypic features that are similar to the interstitial cells of Cajal. Recently, investigators have begun to evaluate these lesions in a site-specific manner and have found that, in addition to morphologic differences between them, their biologic behavior also appears to be linked to their anatomic location. Many of these studies have emphasized the histologic and immunophenotypic features of GISTs in relation to their sites of origin, however, their site-specific ultrastructural characteristics have received little attention in the literature. In this study, we evaluated 34 GISTs (15 gastric, 12 small intestinal, 4 colonic, and 3 omental) for a variety of ultrastructural features in an effort to identify site-specific similarities and differences. Tumors predominantly composed of epithelioid cells were more commonly seen in gastric (60%) and omental (67%) tumors than in those of the small intestine (33%) and colon (0%). Cytoplasmic filaments and intercellular junctions were commonly seen in tumors from all locations, the filaments frequently forming paranuclear aggregates in the epithelioid cells. Tumors from all sites were composed of cells with surface filopodia and interdigitating cell processes, but in tumors of the stomach and omentum the filopodia were usually short and minimally intertwined, whereas those of small and large intestinal GISTs were characteristically long and complex. Basal lamina, though poorly formed, was present only in tumors of gastric and omental origin (13% and 67%, respectively). Pinocytotic vesicles were also seen in tumors from these sites (33% of gastric tumors and 67% of omental lesions) as well as those of the small intestine (17%) and the colon (25%). None of the gastric or omental tumors had microtubules; they were, however, seen in small intestinal (33%) and colonic (25%) stromal tumors. Skenoid fibers were seen in 33% of small intestinal GISTs and 1 metastatic gastric GIST. Overall, gastric and omental tumors have better developed features of myogenic differentiation and have blunt filopodia and minimally intertwined cell processes. Indeed, these 2 groups are indistinguishable ultrastructurally, raising the possibility that the genesis of omental GISTs is similar to that of gastric stromal tumors. Small intestinal stromal tumors have characteristic interdigitating cell processes and numerous elongate filopodia-like structures harboring intercellular junctions as well as microtubules and extracellular skenoid fibers. The constituent cells in colonic stromal tumors, while more reminiscent of small intestinal stromal, were frequently more primitive in appearance. In conclusion, GISTs from different anatomic locations share many overlapping ultrastructural characteristics; however, a few features are distinctive. It is hoped that these findings will aid in their recognition and contribute to the classification of this heterogeneous group of neoplasms.
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PMID:Gastrointestinal stromal tumors: an ultrastructural study. 1461 38

Gastrointestinal stromal tumors (GIST) represent compared to carcinomas a rare group of neoplasias of the gastro-intestinal tract of unclear dignity. We report the example of a patient suffering from a big retrogastral located gastrointestinal stromal tumor which had been detected as an incidental finding without previous complaints. Because origin and dignity of the process could not definitely be diagnosed, total resection (R0-resection) without systemic lymphadenectomy of the process measuring 11.5 cm x 11 cm x 7 cm was performed. Mitotic activity and tumor-size are regarded as predictive factors of potenzial malignancy of GISTs. In general tumors with low mitotic activity of up to 5 mitoses per 50 high power fields (HPFs) and a diameter smaller than 5 cm are regarded as benign. In the presented case, up to 4 mitoses per 50 HPFs could be detected and thus, in connection with tumor-size, an uncertain biological behaviour of the process has to be expected. Since no generally accepted consensus on the treatment of the GISTs exists, also patients originally suffering from tumors regarded as borderline-malignant should undergo a close-meshed follow-up in regular intervals.
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PMID:[Retrogastral located gastrointestinal stromal tumor (GIST) as a sonographically detected rare incidental finding]. 1208 85

As a result of major recent advances in understanding the biology of gastrointestinal stromal tumors (GISTs), specifically recognition of the central role of activating KIT mutations and associated KIT protein expression in these lesions, and the development of novel and effective therapy for GISTs using the receptor tyrosine kinase inhibitor STI-571, these tumors have become the focus of considerable attention by pathologists, clinicians, and patients. Stromal/mesenchymal tumors of the gastrointestinal tract have long been a source of confusion and controversy with regard to classification, line(s) of differentiation, and prognostication. Characterization of the KIT pathway and its phenotypic implications has helped to resolve some but not all of these issues. Given the now critical role of accurate and reproducible pathologic diagnosis in ensuring appropriate treatment for patients with GIST, the National Institutes of Health convened a GIST workshop in April 2001 with the goal of developing a consensus approach to diagnosis and morphologic prognostication. Key elements of the consensus, as described herein, are the defining role of KIT immunopositivity in diagnosis and a proposed scheme for estimating metastatic risk in these lesions, based on tumor size and mitotic count, recognizing that it is probably unwise to use the definitive term "benign" for any GIST, at least at the present time.
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PMID:Diagnosis of gastrointestinal stromal tumors: A consensus approach. 1450 50

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. Until recently, surgery has been the only effective therapy for GIST. However, even after complete resection of tumor, many patients still eventually die of disease recurrence. Conventional chemotherapy and radiation therapy have been of limited value. Within the last few years, it was discovered that most GISTs have a gain-of-function mutation in the c-kit proto-oncogene. This results in ligand-independent activation of the KIT receptor tyrosine kinase and an unopposed stimulus for cell growth. STI-571 is a small molecule that selectively inhibits the enzymatic activity of the ABL, platelet-derived growth factor receptor, and KIT tyrosine kinases and the BCR-ABL fusion protein and is a landmark development in cancer therapy. Its clinical development marks a new era of rational and targeted molecular inhibition of cancer that emanates from direct collaborations between scientists and clinicians. It provides proof of the principle that a specific molecular inhibitor can drastically and selectively alter the survival of a neoplastic cell with a particular genetic aberration. The advent of STI-571 has markedly altered the clinical approach to GIST. It has proven to be effective in metastatic GIST and is also under investigation as a neoadjuvant and adjuvant therapy.
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PMID:Clinical management of gastrointestinal stromal tumors: before and after STI-571. 1209 71

This paper reviews data on the prognosis of gastrointestinal stromal tumors (GISTs). These tumors are specific KIT-expressing and KIT-signaling-driven mesenchymal tumors, many of which have KIT-activating mutations. GISTs occur in the entire gastrointestinal (GI) tract and may also arise from the omentum, mesenteries, and retroperitoneum. They range from small benign tumors to sarcomas at all sites of occurrence. A KIT tyrosine kinase inhibitor, STI-571 (imatinib [Gleevec]; Novartis, Basel, Switzerland), has recently shown promise in the treatment of metastatic GISTs. Understanding the natural history of GIST before introduction of STI-571 will help assess the impact and position of this new treatment. The frequency of benign versus malignant GISTs varies between sites. Benign GISTs outnumber malignant GISTs in the stomach, whereas malignant GISTs are more common in the intestines. Tumors that have metastasized at presentation have a very poor prognosis. Traditionally, the 3 key prognostic factors have been mitotic rate, tumor size, and site. Tumors that are small (< or =2 cm) and show mitotic activity not exceeding 5 mitoses per 50 high-power fields (HPFs) have an excellent prognosis, probably independent of site, although this has not been shown specifically for all sites. In the stomach, most epithelioid GISTs are benign, provided that mitotic counts do not exceed 5/50 HPFs. However, a small proportion of tumors apparently lacking mitotic activity do metastasize. Tumors with a mitotic rate >5/50 HPFs usually have a malignant behavior. The Ki67 index may help identify tumors with malignant potential, but large site-specific series are not yet available. Genetic markers, including DNA-copy number changes, telomerase activity, and KIT mutation status, may be useful in more accurately identifying tumors with malignant potential.
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PMID:Evaluation of malignancy and prognosis of gastrointestinal stromal tumors: a review. 1209 72

A 56-year-old man was hospitalized because of swelling of the right upper extremity and anemia. A diagnosis of superior vena cava (SVC) syndrome caused by lymphogenous metastasis was made after chest computed tomography (CT) scan and biopsy of cervical lymph nodes were carried out. Standard examinations, such as abdominal CT scan and endoscopies of the upper and lower gastrointestinal tract, failed to find the primary lesion. However, selective angiography of the superior mesenteric artery (SMA) showed a clear stain of bleeding vessels in the small intestine. Laparotomy was performed, and immunohistochemical findings revealed sarcomatoid carcinoma in the small intestine (a rarely seen neoplasm). This aggressive carcinoma, which showed negative reactivity with CD34, CD117 (c-kit), and S-100 was clearly distinguished from other mesenchymal tumors, such as malignant gastrointestinal stromal tumor (GIST) and malignant fibrous histiocytoma (MFH).
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PMID:Small-intestinal sarcomatoid carcinoma with superior vena cava syndrome. 1210 83

Carney's triad represents the association of gastric gastrointestinal stromal tumor, pulmonary chondroma, and extraadrenal paraganglioma. Only 79 cases of this rare condition have been described. Here, the authors describe the unusual case of a 14-year-old boy who presented with a complete Carney's triad. This is only the second reported case in the world literature of a patient manifesting a complete Carney's triad at presentation. The management of each tumor is discussed.
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PMID:An unusual case of complete Carney's triad in a 14-year-old boy. 1214 13

Gain-of-function c-kit gene mutations and immunoreactivity of the c-kit protein CD117 in many gastrointestinal stromal tumors (GISTs) seem to support the idea that GISTs form a biologically distinct entity. In this study, the clinicopathologic features of 171 cases of GIST at a single institution were investigated for accurate diagnosis, and their relative risk for mortality was estimated by multivariate analysis. A GIST was defined diagnostically as a mesenchymal spindle or epithelioid cell lesion arising in the wall of the gastrointestinal tract with consistent immunoreactivity for CD117. The 171 patients with GISTs comprised 96 males (56.1%) and 75 females (43.9%), with a mean age of 59.4 years. One hundred and forty-five tumors (84.8%) occurred in the stomach, 18 (10.5%) in the small intestine, 6 (3.5%) in the rectum, and 2 (1.2%) in the esophagus. The median tumor size was 4.5 cm (range, 1.2 to 38 cm). Spindle-cell GISTs were present in 132 cases (77.2%); mixed GISTs, in 25 cases (14.6%); and epithelioid GISTs, in 14 cases (8.2%). Ten cases (55.6%) of spindled small intestine GIST contained eosinophilic skeinoid fibers. Immunoreactivity for CD34, h-caldesmon, alpha-smooth-muscle actin (SMA), desmin, and S-100 was observed in 156 (91.2%), 131 (76.6%), 46 (26.9%), 7 (4.1%), and 14 (8.2%) tumors, respectively. The percentage of CD34 positivity (38.8%) was low, in contrast with the high percentage of reactivity for SMA (77.8%) and S-100 (44.4%) in small intestine GISTs. By our histologic grading system using tumor differentiation, MIB-1 score, and necrosis, 129 tumors (75.4%) were classified as low grade and 42 tumors (24.6%) were classified as high grade. With a median follow-up period of 83.5 months for 122 living patients, the 5-year and 10-year survival rates were 81.7% and 67.4%, respectively. Multivariate analysis showed that both tumor size >10 cm and high grade were significantly associated with a poor outcome. As a result, GISTs >10 cm or high grade, 5 to 10 cm and low grade, and < or =5 cm and low grade were regarded as high risk, intermediate risk, and low risk for mortality, respectively. In conclusion, it is important to recognize GISTs that have a specific molecular pathogenesis and to separate them from other mesenchymal tumors with optimal immunostaining for CD117 when making a diagnosis and prognostic classification based on tumor size and MIB-1 grade.
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PMID:Gastrointestinal stromal tumor: consistent CD117 immunostaining for diagnosis, and prognostic classification based on tumor size and MIB-1 grade. 1215 68

Gastrointestinal stromal tumors (GISTs) are a heterogeneous group of mesenchymal tumors with a wide spectrum of histologic features and consistent expression of c-Kit. We describe an 85-year-old woman who presented with left lower quadrant abdominal pain and was subsequently diagnosed as having a malignant GIST. The tumor was composed of short fascicles of spindle cells. In addition to the presence of tumor giant cells, the tumor also demonstrated many osteoclast-like giant cells, a feature that has not been previously described in the literature. These giant cells expressed histiocytic markers CD68 and alpha(1)-antitrypsin but not c-Kit, a marker for GISTs. Electron microscopy showed no features of smooth muscle differentiation in the giant cells. The possible origin of the osteoclast-like giant cells is discussed in the context of immunohistochemical and ultrastructural characteristics.
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PMID:A malignant gastrointestinal stromal tumor with osteoclast-like giant cells. 1217 99

Gastrointestinal stromal tumor (GIST), a stromal tumor of the gastrointestinal tract defined as CD117 (c-kit)-positive neoplasm, occurs primarily in adults. GIST with CD117 (c-kit) mutation and certain cytogenetic abnormalities is associated with malignancy, though a definite relationship between prognosis and molecular alterations remains to be elucidated. We report the cytologic features of an epithelioid GIST arising in the stomach of a child and metastatic to the liver, and the molecular mutational analysis of both the primary gastric tumor and the liver metastasis. Literature of pediatric GISTs was also reviewed. Fine needle aspiration of the liver metastasis, processed by Ultrafast Papanicolaou stain, showed fragments of cohesive small epithelioid cells with bland oval nuclei and unipolar cytoplasm transected by capillaries. Immunohistochemically, all nodules in the stomach and liver expressed CD117 (c-kit). Interestingly, some of the gastric tumor clusters were uniformly CD34 positive, whereas others were uniformly CD34 negative, suggesting heterogeneity of tumor clones. The presence of neurosecretory granules further subtyped the tumor into gastric autonomic nerve tumor (GANT). Molecular mutational analysis, performed in both the gastric tumor and the liver metastasis, showed no sequence abnormality in exons 9, 11, and 13 of CD117 (c-kit). Cytogenetic study revealed normal karyotype. These features might suggest a different molecular mechanism leading to malignancy in certain GISTs arising in children.
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PMID:Epithelioid gastrointestinal stromal tumor of the stomach with liver metastases in a 12-year-old girl: aspiration cytology and molecular study. 1265 41


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