Mondo Description Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal (GI) tract, typically presenting in adults over the age of 40 (mean age 63), and only rarely in children, in various regions of the GI tract, most commonly the stomach or small intestine but also less commonly in the esophagus, appendix, rectum and colon. GISTs can be asymptomatic or present with various non-specific signs, depending on the location and size of tumor, such as loss of appetite, anemia, weight loss, fatigue, abdominal discomfort or fullness, nausea, vomiting, as well as an abdominal mass, blood in stool, and intestinal obstruction. GISTs can also be seen in familial syndromes such as Carney triad and neurofibromatosis type 1.

Uniprot Description Common mesenchymal neoplasms arising in the gastrointestinal tract, most often in the stomach. They are histologically, immunohistochemically, and genetically different from typical leiomyomas, leiomyosarcomas, and schwannomas. Most GISTs are composed of a fairly uniform population of spindle-shaped cells. Some tumors are dominated by epithelioid cells or contain a mixture of spindle and epithelioid morphologies. Primary GISTs in the gastrointestinal tract commonly metastasize in the omentum and mesenteries, often as multiple nodules. However, primary tumors may also occur outside of the gastrointestinal tract, in other intra-abdominal locations, especially in the omentum and mesentery.