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Gastrointestinal stromal tumor
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Conditions

Gastrointestinal stromal tumor

A gastrointestinal stromal tumor (GIST) is a tumor arising from specialized cells in the digestive tract, often linked to specific genetic mutations that trigger abnormal cell growth.

Overview

GISTs most commonly occur in the stomach or small intestine and are thought to grow from interstitial cells of Cajal (ICCs). While most cases are sporadic, some are familial. A rare form, SDH-deficient GIST, typically occurs in childhood or young adulthood.

Symptoms

Small tumors may be asymptomatic. When symptoms occur, they include:

  • Abdominal pain or swelling
  • Nausea and vomiting
  • Loss of appetite and weight loss
  • Bleeding into the gastrointestinal tract, leading to low red blood cell counts (anemia), weakness, and tiredness
  • Black, tarry stools or vomiting of blood

Familial cases may involve multiple tumors, noncancerous overgrowth (hyperplasia) of other cells, and skin conditions like urticaria pigmentosa.

Causes

GISTs are driven by genetic changes that keep cell signaling pathways constantly turned on, leading to uncontrolled growth:

  • KIT gene mutations: Associated with about 80% of cases.
  • PDGFRA gene mutations: Associated with about 10% of cases.
  • SDH-deficient GIST: Caused by mutations in SDHA, SDHB, SDHC, or SDHD genes, which reduce the function of the succinate dehydrogenase (SDH) enzyme.

Inheritance

Most GISTs are sporadic, caused by a somatic mutation that occurs only in tumor cells during a person's lifetime. Familial GISTs associated with KIT or PDGFRA mutations typically follow an autosomal dominant pattern, where one inherited altered gene increases tumor risk, and a second somatic mutation is required for tumor formation. SDH-deficient GIST also follows an autosomal dominant pattern.

Frequently Asked Questions

KIT exon 11 mutations are the most common and predict a good response to the tyrosine‑kinase inhibitor imatinib. Most patients start imatinib (400 mg daily) as adjuvant therapy after resection, and the mutation type helps determine dose and duration.
Yes. Black, tarry stools (melena) indicate upper‑GI bleeding, which can be caused by a GIST that has ulcerated into the lumen. If you also have dizziness, rapid heartbeat, or fainting, seek emergency care immediately; prompt endoscopy or imaging can locate the source and stop the bleed.
Diagnosis usually starts with a contrast‑enhanced CT or MRI of the abdomen to define tumor size and location. Endoscopic ultrasound (EUS) with fine‑needle aspiration can obtain tissue. Pathology looks for CD117 (c‑KIT) and DOG1 positivity, and molecular testing for KIT, PDGFRA, or SDH mutations guides therapy.
If a first‑degree relative had a GIST, especially at a young age, hereditary GIST should be considered. Testing for germline KIT, PDGFRA, or SDH gene mutations is recommended, and if a pathogenic variant is found, regular imaging (e.g., annual CT) and counseling for family members are advised.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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