What type of tumor is a gastrointestinal stromal tumor (GIST)?

A gastrointestinal stromal tumor (GIST) is classified as a mesenchymal tumor because it originates from the interstitial cells of Cajal, which are part of the digestive tract's connective tissue. These tumors are characterized by mutations in the KIT gene or PDGFRA gene, leading to abnormal cell growth in the smooth muscle layer of the gastrointestinal tract.

Mesenchymal tumors arise from the mesoderm, which gives rise to connective tissues, bone, muscle, and blood vessels. GISTs specifically exhibit characteristics of smooth muscle tumors and are often found in the stomach or small intestine. Their origin from mesenchymal cells differentiates them from tumors that arise from epithelial cells, neuroendocrine cells, or lymphoid tissue, which fall into other categories. Therefore, understanding that GISTs are derived from the connective tissues of the gastrointestinal tract helps clarify their classification as mesenchymal tumors.