Gastrointestinal Stromal Tumor

One of the most common mesenchymal tumors of the GI tract.  Patients may present with early satiety, gastrointestinal bleeding, vague abdominal pain. Actual obstruction is rare.  The tumor can be large by time the diagnosis is made and patients may present with metastases (usually liver). On imaging studies GISTs appear as intramural masses.
Internal calcifications may be present. As the tumor grows larger it can undergo necrosis and ulcerate. GISTs can directly invade adjacent structures in the abdomen. Mets are ususlly to the liver. Spread to the peritoneal cavity can be seen.Metastatic adenopathy  is uncommon. 70% of GISTs occur in the stomach, 20% in the small intestine and less than 10% in the esophagus. GISTs are  connective tissue tumors. They are thought to arise from interstitial cells of Cajal (part of the autonomic nervous system of the intestinethat control motility.)


Most GISTs arise from a mutation in the c-kit gene.  This gene encodes for a transmembrane growth factor receptor called stem cell factor (scf), a tryosine kinase receptor. Mutations to c-kit usually occur in the intracellular domain of the receptor and cause it to be active independent of scf binding. GISTs that do not have a c-kit mutation often have a mutatuion in a related tyrosine kinase receptor, platelet derived growth factor receptor alpha (PDGFR-a).

GIST tumors with c-kit or PDGFR-a mutations can be treated with Imatinib (GLEEVAC), a tyrosine kinase inhibitor.

Miettinen M, Lasota J. "Gastrointestinal stromal tumors: review on morphology, molecular pathology, prognosis, and differential diagnosis". Arch. Pathol. Lab. Med. 130 (10): 1466–78