Sarcomas are cancers that can develop in any soft tissue in the body, such as fat, muscle, fibrous tissue (like tendons and ligaments), synovial tissue (in joints), blood vessels, lymph vessels or nerves. Small intestine sarcomas account for about 10% of all small intestine cancers. Most small intestine sarcomas are gastrointestinal stromal tumours (GISTs), which can develop anywhere in the gastrointestinalgastrointestinalReferring to or having to do with the digestive organs, particularly the stomach, small intestine and large intestine. (GI) tract. After the stomach, GISTs develop most commonly in the small intestine.
A small intestine GIST starts in the interstitial cells of Cajal, which are cells in the wall of the small intestine. Most GISTs have a particular gene mutation called KIT, which distinguishes them from other sarcomas. GISTs occur throughout the small intestine, but most occur in the jejunum and ileum.
Most people with GISTs present with bleeding in the GI tract. These tumours have a lot of blood vessels in them, so bleeding is a common symptom. They can also cause a perforation or obstruction in the small intestine, which can lead to abdominal pain and weight loss.
GISTs may become quite large before a person is diagnosed. Many tumours are larger than 5 cm (2 inches) at diagnosis. Large tumours are more aggressive than small ones. These tumours commonly spread (metastasize) to the liver and lungs. GISTs rarely spread to nearby (regional) lymph nodes.
GISTs of the small intestine are graded and staged differently than carcinomas of the small intestine.