The understanding of mesenchymal neoplasms of the gastrointestinal tract has evolved dramatically over the last two decades since gastrointestinal stromal tumor (GIST) was described as the most common stromal tumor arising anywhere from the esophagus to the ano-rectum. Although morphologically similar to other benign and malignant smooth muscle and neural stromal neoplasms, GIST constitutes a distinct group of rare gastrointestinal tract tumors that originate from the interstitial cells of Cajal, regulators of gut peristalsis that normally express CD117, which is the product of the c-KIT proto-oncogene that encodes a tyrosine kinase receptor that regulates cellular proliferation in GISTs. Virtually all GISTs occur from mutations of the c-KIT oncogene and exhibit consistent expression of c-KIT (CD117), which is considered the most specific criterion for a diagnosis of GIST. Gastrointestinal stromal tumors vary in their behavior and several features have to be considered to assess their malignant potential. The advent of sophisticated imaging techniques for the evaluation and sampling of stromal tumors of the gastrointestinal tract has resulted in improved detection of GISTs. The identification of a novel tumor-specific target in c-KIT resulted in the development of a tyrosine kinase-inhibitor (imatinib mesylate) that provides an encouraging option for treating GISTs. This article reviews recent advances in the understanding of the cell biology, diagnosis, and therapy of GISTS.
Objective. To study the yield of endoscopic ultrasonographically guided fine-needle aspiration cytologic examination in the diagnosis of submucosal masses. Methods. From 1999 to 2003, 10 patients underwent ultrasonographically guided fine-needle aspiration for the cytologic diagnosis of submucosal masses in our institution. The endoscopic ultrasonography records and the cytology database were consulted, and the reports were analyzed, as were slide material and the technical aspects related to these procedures. All procedures were performed under conscious sedation and cardiorespiratory monitoring on an outpatient basis. Ten patients (4 men and 6 women; mean age, 60.8 years) were studied. Results. Eight lesions were located in the stomach, and 2 were located in the esophagus, with a mean diameter of 3.3 cm. An experienced cytopathologist was present on-site during all procedures for assessment of adequacy and preliminary cytologic examination. Cytologic diagnoses were obtained in 8 cases as follows: 6 gastrointestinal stromal tumors, 1 organizing submucosal hematoma, and 1 low-grade mucosa-associated lymphoid tissue-associated lymphoma. Two cases consisted of scant gastric epithelium only and were considered nondiagnostic. The cytologic diagnoses guided further clinical treatment. Conclusions. Ultrasonographically guided fine-needle aspiration with cytopathologic analysis has a high accuracy rate (80%) for diagnosing submucosal lesions. These findings potentially affect clinical decision making. Key words: endoscopic ultrasonography; fineneedle aspiration; submucosal tumors. he term submucosal tumor (SMT) refers to any protrusion or indentation observed through the gastrointestinal lumen having an intact mucosal surface and discovered either incidentally during routine endoscopy or because of associated symptoms such as abdominal pain, dysphagia, and gastrointestinal bleeding.1 These symptoms can be related either to the presence of intramural masses or to external compression of the gastrointestinal tract wall.Endoscopy alone has suboptimal accuracy of as low as 40% for identifying the cause of submucosal bulges.
2Usually the mucosal surface is normal, and conventional forceps biopsy results are frequently negative. Other noninvasive imaging methods such as transabdominal ultrasonography and computed tomography are also suboptimal for evaluating submucosal indentations.
3Endoscopic ultrasonography (EUS) combines the endoscopic view with ultrasonographic images generated by a
This paper reviews the role of endosonography and optical coherence tomography (OCT) for imaging of Barrett's esophagus (BE). The routine use of endoscopic ultrasound (EUS) to screen patients with BE is neither justified nor cost effective. EUS does appear to have a role in patients who have BE and high-grade dysplasia or intramucosal carcinoma, in whom a non-operative therapy is being contemplated. For patients with a diagnosis of esophageal cancer with or without BE, EUS is superior to computed tomography or magnetic resonance imaging for assessing esophageal wall penetration and for detecting regional lymph node involvement. In its current state, OCT is not yet ready for application in clinical practice. However, given its superior resolution compared with other modalities such as EUS, OCT has great potential as a powerful adjunct to standard endoscopy in surveillance of BE and may enhance the ability of endoscopists to detect high-grade dysplasia at an early stage. With further technical refinement, this technique may become a mainstay in the surveillance of BE and other premalignant conditions of the gastrointestinal tract.
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