الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The term gastrointestinal stromal tumors (GISTs) has traditionally been used as a descriptive term for soft tissue tumors of the gastrointestinal tract. Incidence of gastrointestinal stromal tumors is about 1-3 % of all gasterointestinal malignancies and occurs in 10-20 per one million people. In the past, some were thought to start in the muscle layer of the gastrointestinal tract, and some were thought to start in nerve cells. This is because the tumor cells look like muscle or nerve cells under the microscope. They were often thought to be related to sarcomas -- cancers that start in the muscle, bones of the legs and arms, or other connective tissues. It is now believed that they start in special cells found in the wall of the gastrointestinal tract, called the interstitial cells of Cajal (ICCs), or in very early cells that can develop into interstitial cells of Cajal
Interstitial cells of Cajal are part of the autonomic nervous system, which sends signals to the gastrointestinal tract. Some have called these cells the pacemakers of the gastrointestinal tract. The nerve signals they send cause muscles of the digestive organs to contract, which helps to move food and liquid through the GI tract Not all gastrointestinal stromal tumors are cancerous. Some are benign that they don’t invade into other areas or spread to other parts of the body Gastrointestinal stromal tumors are a subset of gastrointestinal mesenchymal tumors of varying differentiation. Previously, these tumors were classified as gastrointestinal leiomyomas, leiomyosarcomas, leiomyoblastomas, or schwannomas, on the basis of histologic findings and the fact that these tumors apparently originate in the muscularis propria layer of the intestinal wall. With the advent of immunohistochemical staining techniques and ultrastructural evaluation, gastrointestinal stromal tumors now are recognized as a distinct group of mesenchymal tumors. Gastrointestinal stromal tumors account for approximately 80% of gastrointestinal mesenchymal tumors The literature about gastrointestinal stromal tumors remains confusing because tumor classification and terminology are being continually refined. Furthermore, the exact definition of gastrointestinal stromal tumors varies among authors. Some use the term to describe any gastrointestinal submucosal mesenchymal tumor that is not myogenic (eg, leiomyosarcoma) or neurogenic (eg, schwannoma) in origin Diagnosis of gastrointestinal stromal tumors depends on medical history, symptoms, risk factors, one or more types of imaging tests, and biopsy