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Extra-gastrointestinal stromal tumor of the greater omentum: report of a case and review of the literature
Christian Franzini, Luciano Alessandri, Irene Piscioli, Salvatore Donato, Rosario Faraci, Luca Morelli, Franca Del Nonno, Stefano Licci
World Journal of Surgical Oncology , 2008, DOI: 10.1186/1477-7819-6-25
Abstract: We here report the clinical, macroscopic and immunohistological features of an EGIST arising in the greater omentum of a 74-year-old man, with a discussion on the clinical behavior and the prognostic factors of such lesions and a comparison with the gastrointestinal counterpart.The EGISTs in the greater omentum can grow slowly in the abdomen for a long time without clinical appearance. In most cases a preoperative diagnosis is not possible, and the patient undergoes a surgical operation for the generic diagnosis of "abdominal mass". During the intervention it is important to achieve a complete removal of the mass and to examine every possible adhesion with the gastrointestinal wall. Yamamoto's criteria based on the evaluation of the mitotic rate and the MIB-1 labelling index seems to be useful in predicting the risk for recurrence or metastasis. More studies are necessary to establish the prognostic factors related to localization and size of the EGIST and to evaluate the impact of the molecular characterization as an outcome parameter related to the molecular targeted therapy. In absence of these data, an accurate follow-up is recommended.Stromal tumors represent the majority of primary non-epithelial neoplasms of the digestive tract and are collectively defined gastrointestinal stromal tumors (GISTs). They histologically, immunohistochemically and genetically differ from leiomyomas, leiomyosarcomas and schwannomas. GISTs may be defined as intra-abdominal mesenchymal tumors most frequently expressing the KIT protein, having a gain-of-function mutation in the regulatory juxtamembrane domain of the c-kit gene or an activating mutation in another class III receptor tyrosine kinase gene, the PDGFRA gene, which encodes the platelet derived growth factor receptor-alpha receptor tyrosine kinase protein [1,2]. The KIT protein can be detected by immunohistochemical assays for the CD117 antigen.GISTs are most commonly found in the stomach (40 to 70%), small intestine (20 to
A ruptured large extraluminal ileal gastrointestinal stromal tumor causing hemoperitoneum  [cached]
Shoji Hirasaki, Kohei Fujita, Minoru Matsubara, Hiromitsu Kanzaki, Hiromichi Yamane, Masato Okuda, Seiyuu Suzuki, Atsuko Shirakawa, Hideyuki Saeki
World Journal of Gastroenterology , 2008,
Abstract: We describe an 87-year-old woman with a large ileal gastrointestinal stromal tumor (GIST) causing hemoperitoneum. A CT scan demonstrated a large heterogeneous mass measuring about 13 cm × 11 cm in the pelvis and hemoperitoneum, with a non-uniform enhancement pattern. The mass was diagnosed as a GIST originating from the gastrointestinal tract. She underwent an urgent laparotomy and an ileal GIST with a rupture was found 130 cm from the anal to the Treitz’s ligament. Hemoperitoneum caused by ileal GIST rupture is a rare condition. Bleeding in the large tumor leading to rupture of the capsule might cause hemoperitoneum in the present case.
Gastrointestinal Stromal Tumors: Molecular Mechanisms and Targeted Therapies  [PDF]
Erinn Downs-Kelly,Brian P. Rubin
Pathology Research International , 2011, DOI: 10.4061/2011/708596
Abstract: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and are diverse not only in their clinical behavior but also in their histologic appearance. GISTs are insensitive to conventional sarcoma chemotherapy and radiation. However GISTs are sensitive to small-molecule tyrosine kinase inhibitors as 85–90% of GISTs have KIT or platelet-derived growth factor receptor alpha (PDGFRA) mutations, which drive tumorigenesis. This review will briefly touch on the clinicopathological features of GIST, while the majority of the review will focus on the clinical and treatment ramifications of KIT and PDGFRA mutations found in GIST. 1. Background The last twenty years have seen great advances in the understanding of gastrointestinal stromal tumors (GISTs), from identifying their typical immunohistochemical phenotype and the molecular alterations that drive these tumors to the knowledge of their biologic potential and the use of effective tryosine kinase inhibitor targeted therapy. GISTs are the most common mesenchymal neoplasms of the gastrointestinal tract, and although insensitive to conventional sarcoma chemotherapy and radiation, they have shown dramatic clinical response to targeted kinase therapy. Activating mutations in KIT or platelet-derived growth factor receptor alpha (PDGFRA) have been identified in up to 80% and 10% of GISTs, respectively, and these mutually exclusive gain-of-function mutations play a fundamental role in GIST development by constitutively activating tyrosine kinase receptors [1–6]. Imatininib mesylate (ST1571; Gleevec, Novartis, East Hanover, NJ) is a selective tryosine kinase inhibitor that targets KIT and PDGFRA. The original indication was for the treatment of metastatic or unresectable GISTs with patients showing clinical responses in up to 80% of cases [7]; current FDA-approved labeling includes use in the adjuvant setting following complete gross resection of GISTs [8]. GISTs may occur anywhere in the gastrointestinal tract but are most common in the stomach and small bowel (roughly 60% and 30%, resp.), while 10% arise in other parts of the gastrointestinal tract (esophagus, colon, and rectum), and a small percentage are extragastrointestinal, arising in the mesentery, omentum, retroperitoneum, or pelvis [9, 10]. Once thought to represent smooth muscle neoplasms [11–13], GISTs are now known to share features with interstitial cells of Cajal (ICC), based on ultrastructure findings and immunophenotyping [14–19]. ICC are present within the interstitium of the muscularis propria
Extra-gastrointestinal stromal tumor of the omentum: a rare case report and review of the literature  [cached]
Dimitris Fagkrezos,Zisis Touloumis,Maria Giannila,Charalampos Penlidis
Rare Tumors , 2012, DOI: 10.4081/rt.2012.e44
Abstract: Gastrointestinal stromal tumors (GIST) are uncommon mesenchymal spindle-cell or epithelioid neoplasms, located mainly with higher frequency in the stomach and small bowel. GISTs represent the majority of primary non-epithelial neoplasms of the digestive tract, most frequently expressing the KIT protein a transmembrane tyrosine kinase receptor for stem cell factor. Extra-gastrointestinal stromal tumors tend to present In fewer than 5% of cases; they originate primarily from the mesentery, omentum or peritoneum. Furthermore, these extra-gastrointestinal tumors (EGIST) tend to be more common in patients over the age of 50 years. EGISTs are neoplasms with overlapping immunohistological features, occurring in the abdomen outside the gastrointestinal tract with no connection to the gastric or intestinal wall. We describe here a rare case of EGIST of the lesser omentum and report the clinical, macroscopic, immunohistological and radiological features of an EGIST arising in the lesser omentum of a 63-year old man. Clinical course and the prognostic factors of such lesions will also be discussed. EGISTs in the lesser omentum can grow slowly and remain silent despite a large tumor size. In most cases, a pre-operative diagnosis is not possible, and the patient undergoes a surgical operation for the generic diagnosis of abdominal mass. During the intervention it is important to achieve a complete removal of the mass and to examine every possible adhesion to the gastrointestinal wall.
The role of mutational analysis of KIT and PDGFRA in gastrointestinal stromal tumors in a clinical setting
Alessandra Maleddu, Maria A Pantaleo, Margherita Nannini, Guido Biasco
Journal of Translational Medicine , 2011, DOI: 10.1186/1479-5876-9-75
Abstract: Mutation of tyrosine kinase receptors is a mechanism of drug resistance that can occur either at the beginning of treatment (primary resistance) or during the course of therapy (secondary resistance). In addition, mutational status can predict the response to treatment with tyrosine kinase inhibitors, but the role of mutational status as a prognostic factor remains controversial.Evidence of a potential role of mutational status as a prognostic factor has emerged over the past decade. The presence of KIT exon 11 insertion/deletion involving either one or both Trp557-Lys558 amino acids correlates with a poorer clinical outcome if compared to patients with tumors wild type for KIT exon 11 mutations. A malignant clinical behavior has also been documented for KIT exon 13 and KIT exon 9 mutant GIST. Patients with GIST harboring a PDGFRA mutation seem to have a better prognosis than the others.The aim of this paper is to review the clinical significance of tyrosine kinase mutational status.Gastrointestinal stromal tumors (GIST) are rare tumors of the gastrointestinal tract. They arise mostly in the stomach, followed by the small bowel and colon. Less frequently they are found in the rectum, esophagus or in an extra-gastrointestinal location. The biology of GIST has been widely investigated since Hirota et al. [1] demonstrated mutations of the KIT receptor as a pathogenic mechanism of GIST. Other mutations affecting KIT exons 9, 13 and 17 have been demonstrated [2,3]. About 15% of GIST do not express KIT mutations and of these approximately 5 to 7% have a mutation affecting the gene encoding for PDGFRA [4]. There is also a small subgroup of GIST, called wild type (WT), which do not harbor either KIT or PDGFRA mutations [5].KIT and PDGFRA are two trans-membrane receptors that belong to the type III tyrosine kinase family whose natural ligands are stem cell factor (SCF) and platelet-derived growth factor (PDGF). Both receptors have a similar structure with five immunoglobulin
Pitfalls in mutational testing and reporting of common KIT and PDGFRA mutations in gastrointestinal stromal tumors
Sabine Merkelbach-Bruse, Wolfgang Dietmaier, Laszlo Füzesi, Andreas Gaumann, Florian Haller, Julia Kitz, Antje Krohn, Gunhild Mechtersheimer, Roland Penzel, Hans-Ulrich Schildhaus, Regine Schneider-Stock, Ronald Simon, Eva Wardelmann
BMC Medical Genetics , 2010, DOI: 10.1186/1471-2350-11-106
Abstract: When comparing results from six different molecular laboratories we recognized the need of standardisation. Six German university laboratories with experience in mutation analysis in GISTs joined together to develop recommendations for the mutation analysis of the most common and clinically relevant hot spots, i. e. KIT exons 9 and 11 and PDGFRA exon 18. We performed a three-phased interlaboratory trial to identify pitfalls in performing molecular analysis in GISTs.We developed a design for a continuous external laboratory trial. In 2009 this external trial was conducted by 19 laboratories via the initiative for quality assurance in pathology (QuiP) of the German Society of Pathology and the Professional Association of German Pathologists.By performing a three-phased internal interlaboratory trial and conducting an external trial in Germany we were able to identify potential pitfalls when performing KIT and PDGFRA mutational analysis in gastrointestinal stromal tumors. We developed standard operation procedures which are provided with the manuscript to allow other laboratories to prevent these pitfalls.Gastrointestinal stromal tumors (GISTs) represent the most common mesenchymal tumors of the gastrointestinal tract. About 50% of GISTs behave clinically aggressive. Since 2001, treatment options have dramatically improved with the introduction of tyrosine kinase inhibitors. On the molecular level, the vast majority of tumors carries activating mutations in the KIT gene or the PDGFRA (platelet derived growth factor receptor alpha) gene, both genes encoding closely related type III tyrosine kinases. The relevance of the mutational status in these genes both for clinical prognosis and for prediction of response to treatment has been increasingly recognized[1,2]. Mutational analyses are now performed in many laboratories worldwide and several protocols have been published. Given the high impact on clinical decisions, mutational testing should meet the highest standard for
A Malignant Gastrointestinal Stromal Tumor of the Gallbladder Immunoreactive for PDGFRA and Negative for CD 117 Antigen (c-KIT)  [PDF]
Athanasios Petrou,Pari Alexandrou,Alexandros Papalambros,Angelica Saetta,Paraskevi Fragkou,Michalis Kontos,Nicholas Brennan,Antonio Manzelli,Kostantinos Bramis,Evangelos Felekouras
HPB Surgery , 2011, DOI: 10.1155/2011/327192
Abstract: Gastrointestinal stromal tumors (GISTs) compose the largest category of well-recognized nonepithelial neoplasms of the gastrointestinal tract (GI). GISTs of the gallbladder are extremely rare tumors. Only four malignant, two benign and one GIST-like tumor of the gall bladder have ever been described. The four malignant GISTs were all positive for CD 117 antigen (c-kit). We present for the first time a malignant gastrointestinal stromal tumor of the gallbladder, immunoreactive for platelet-derived growth factor receptor alpha (PDGFRA) and negative for CD 117 antigen (c-KIT). 1. Introduction Gastrointestinal stromal tumors (GISTs) are well recognized nonepithelial neoplasms of the gastrointestinal tract (GI). After decades of ultra structural, immunohistochemical, and genetic studies, it is now evident that most GISTs are believed to differentiate from Cajal (ICCs) pacemaker cells. The Cajal pacemaker cells are involved in gastrointestinal tract mobility and regulation of autonomous neuronal transmission [1]. The vast majority of GISTs arises in the stomach (50%). Other common sites include the jejunum and ileum (30%), duodenum (5%), colon and rectum (5%), and the esophagus (5%) [2]. Only seven gallbladder GISTs have ever been reported, and of these, four were malignant [3–9]. These malignant gallbladder GISTs were all positive for CD 117 (c-kit) and CD34 or CD117 alone [4–7]. We report a unique gallbladder GIST which is negative for CD 117 and CD 34 but positive for platelet-derived growth factor receptor alpha (PDGFRA). Apart from the extremely rare site of occurrence, GIST of the gallbladder remains a challenging topic and needs to be examined on the basis of histologic findings, clinical history, and molecular profile with the later having significant impact on the treatment strategy. 2. Case Report A 72-year-old woman was admitted to the First Department of Surgery, University of Athens with symptoms suggestive of obstructive jaundice: fever and chills, dark urine, intermittent right upper quadrant (RUQ) abdominal pain, and jaundice. Clinical examination revealed mild tenderness in the RUQ only with no palpable masses. Initial investigations showed a white cell count (WCC) of 11,556?cells/mm3, Total Bilirubin/Direct Bilirubin (TBil/DBil) of 4.80/3.60?mg/dL, alkaline phosphatase (ALP) 440?IU/L, and γ-glutamyl transpeptidase (γ-GTP) 210?IU/L. Tumor markers were within the normal range. Ultrasound demonstrated a thickened gallbladder wall, bile stones, and moderate common bile duct (CBD) dilatation. Bile duct lithiasis was suspected and an endoscopic
Chromosome copy number changes carry prognostic information independent of KIT/PDGFRA point mutations in gastrointestinal stromal tumors
Mara Silva, Isabel Veiga, Franclim R Ribeiro, Joana Vieira, Carla Pinto, Manuela Pinheiro, Bárbara Mesquita, Catarina Santos, Marta Soares, José Dinis, Lúcio Santos, Paula Lopes, Mariana Afonso, Carlos Lopes, Manuel R Teixeira
BMC Medicine , 2010, DOI: 10.1186/1741-7015-8-26
Abstract: In the present study, somatic mutations in KIT and PDGFRA were evaluated by direct sequencing analysis in a consecutive series of 80 GIST patients. For a subset of 29 tumors, comparative genomic hybridization was additionally used to screen for chromosome copy number aberrations. Genotype and genomic findings were cross-tabulated and compared with available clinical and follow-up data.We report an overall mutation frequency of 87.5%, with 76.25% of the tumors showing alterations in KIT and 11.25% in PDGFRA. Secondary KIT mutations were additionally found in two of four samples obtained after imatinib treatment. Chromosomal imbalances were detected in 25 out of 29 tumors (86%), namely losses at 14q (88% of abnormal cases), 22q (44%), 1p (44%), and 15q (36%), and gains at 1q (16%) and 12q (20%). In addition to clinico-pathological high-risk groups, patients with KIT mutations, genomic complexity, genomic gains and deletions at either 1p or 22q showed a significantly shorter disease-free survival. Furthermore, genomic complexity was the best predictor of disease progression in multivariate analysis.In addition to KIT/PDGFRA mutational status, our findings indicate that secondary chromosomal changes contribute significantly to tumor development and progression of GIST and that genomic complexity carries independent prognostic value that complements clinico-pathological and genotype information.Gastrointestinal stromal tumors (GIST) represent the most common mesenchymal tumors of the gastrointestinal tract [1]. A diagnosis of GIST involves a multidisciplinary approach that combines clinical, pathological, and genetic features. Mutually exclusive activating mutations in KIT or PDGFRA occur in 85 to 90% of the cases and are considered primary events in GIST pathogenesis [1-3]. These genes encode type III transmembrane receptor proteins which, upon connection to their respective ligands, activate downstream signaling pathways involved in cell proliferation and survival [4-6
Pendular stromal tumour of the stomach with dominant PDGFRA immunoexpression: Case report and short literature review  [PDF]
Latin?i? Stojan,?olovi? Nata?a,Micev Marjan,?olovi? Radoje
Srpski Arhiv za Celokupno Lekarstvo , 2012, DOI: 10.2298/sarh1204216l
Abstract: Introduction. Gastrointestinal stromal tumours are most frequent mesenchimal tumours of the gastrointestinal tract that originate from Cajal’s interstitial cells that are most frequently CD-117 positive. Stromal tumours of the stomach are the most frequent mesenchimal tumours of the gastrointestinal tract. Such tumours are usually sessile, but rarely pendular when they can be easily removed with a limited local excision of the stomach wall around the pedicle. Major stomach resections are rarely necessary. Case Outline. In a 54-year-old woman with abdominal pain and fever of unknown aetiology, a large spherical mobile and almost painless mass was found within the upper right abdomen. US and CT showed a mainly cystic, partly solid tumour, of 15.5×12.5 cm in diameters. Laboratory data including tumour markers were within normal limits. At operation a mobile and free tumour of the stomach attached to the anterior wall with a 2.5 cm pedicle was found and easily excised. Abdominal mucosa was normal. There was no liver metastasis or peritoneal dissemination. Hystology and imunohistochemistry showed a rare sclerosing sincitial subtype of stromal tumour with imunophenotype heterogenicity with a dominant PDGFRA and rare CD-117 immunoexpression. The postoperative recovery was uneventful. The patient was symptom-free with no sign of recurrence after a year and a half. Conclusion. A rare subtype of histological highly malignant stromal tumour of the stomach, macroscopically of pendular type, that was easily excised, was presented which so far showed a favourable evolution with no signs of recurrence.
Malignant peripheral nerve sheath tumor arising from the greater omentum: Case report
Masashi Miguchi, Yuji Takakura, Hiroyuki Egi, Takao Hinoi, Tomohiro Adachi, Yasuo Kawaguchi, Manabu Shinomura, Masakazu Tokunaga, Masazumi Okajima, Hideki Ohdan
World Journal of Surgical Oncology , 2011, DOI: 10.1186/1477-7819-9-33
Abstract: Primary solid omental tumors are rare and include various types of tumors such as gastrointestinal stromal tumors (GIST), leiomyosarcomas, hemangiocytomas, fibrosarcomas, leiomyomas, liposarcomas, desmoids tumors, fibromas, mesotheliomas, and myosarcomas [1]. Although the pathological spectrum of primary omental tumors is diverse, no report has yet been published on malignant peripheral nerve sheath tumors (MPNSTs) arising from the greater omentum.In this report, we describe the extremely rare case of a Japanese man who had an MPNST arising from the greater omentum.The patient was a 71-year-old man who was healthy by birth and was admitted to our hospital with pain in the right lower abdomen. Physical examination revealed a large, firm, movable mass in the abdomen. The hematological tests, including those for the serum levels of tumor markers such as carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, and CA125, yielded normal results. Abdominal computed tomography (CT) revealed a large (approximately, 9 × 9 cm), well-circumscribed, lobulated mass in the pelvis. The central region of the mass appeared to have low density, while the marginal region was well enhanced in the CT scan (Figure 1A). CT/positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) showed a mass with increased FDG accumulation in the right lower abdomen, without any evidence of distant metastasis (Figure 1B). Evaluation of the gastrointestinal tract did not yield any definite results. The origin of the tumor could not be clearly determined.Exploratory laparotomy was performed under the diagnosis of an intra-abdominal tumor of unknown origin. During laparotomy, it was observed that the tumor arose from the greater omentum and was not connected with the gastrointestinal tract (Figure 2). The tumor was completely excised along with the greater omentum.Gross pathological examination revealed that the tumor was a whitish-grey oval mass, with a maximum diameter of 9 cm (Figure 3
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