Gastrointestinal Stromal Tumor

**Semantic type:** Neoplastic Process

**Definition:** A stromal tumor most commonly seen in the gastrointestinal tract. Rare cases of solitary masses in the omentum or the mesentery have also been reported (extragastrointestinal gastrointestinal stromal tumor). It is a tumor that differentiates along the lines of interstitial cells of Cajal. Most cases contain KIT- or PDGFRA-activating mutations. Until recently, surgery has been the only effective therapy for this tumor. However, many patients still experience recurrence. Conventional chemotherapy and radiation therapy have been of limited value. A KIT tyrosine kinase inhibitor, imatinib mesylate (also known as STI-571 or Gleevec), is now effective in the treatment of relapsed and unresectable cases.

**Synonyms:** - GIST - GIST - GIST, NOS - GISTs - Gastrointestinal Stromal Neoplasm - Gastrointestinal Stromal Tumor (GIST) - Gastrointestinal stromal tumor - Gastrointestinal stromal tumor, NOS - Gastrointestinal stromal tumor, unspecified site - gastrointestinal stromal tumor