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GIST and gastrointestinal neuroendocrine tumours

GIST is a mesenchymal tumour (KIT/CD117), most common in the stomach, resected with clear margins without lymph node dissection and given adjuvant imatinib when high-risk; a small-bowel neuroendocrine tumour is resected with its mesenteric nodes, and carcinoid syndrome appears only with liver metastases.

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Why it matters in the exam

For GIST the exam asks about the origin (interstitial cells of Cajal), the markers (KIT/CD117 and DOG1, sometimes a PDGFRA mutation), the site (stomach in most cases, then small bowel) and the presentation — gastrointestinal bleeding or a mass. Work-up is CT and EUS with biopsy. Treatment is resection with clear margins, without rupturing the tumour and without routine node dissection (nodal spread is rare); the risk of recurrence depends on size, mitotic rate and site, and in high-risk tumours adjuvant imatinib is given for about 3 years. A gastric GIST smaller than 2 cm without symptoms can be followed.

For a small-bowel neuroendocrine tumour (NET) — usually in the ileum — carcinoid syndrome is asked: flushing, diarrhoea, wheezing and right-sided heart valve disease, which appear only with liver metastases (or a tumour draining directly into the systemic circulation), because the liver breaks down serotonin. Diagnosis: 24-hour urinary 5-HIAA and chromogranin A, and the sensitive imaging is Ga-68 DOTATATE PET. Treatment: resection with the mesenteric nodes, sometimes surgery even in disseminated disease; somatostatin analogues (octreotide) for symptoms and to slow the tumour, and octreotide before surgery to prevent a "carcinoid crisis" during anaesthesia.

Key points

• GIST — KIT/CD117, stomach; resection without node dissection.
• High-risk GIST — imatinib for about 3 years.
• Small-bowel NET — resection with the mesenteric nodes.
• Carcinoid syndrome — only with liver metastases; urinary 5-HIAA.
• Octreotide for symptoms and before surgery.

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Sources

• ESMO–EURACAN–GENTURIS Clinical Practice Guidelines: Gastrointestinal stromal tumours, 2022 — Diagnosis, resection and adjuvant imatinib
• ENETS guidance papers for gastroenteropancreatic neuroendocrine tumours, 2023 — Small-intestinal and appendiceal NET, somatostatin analogues
• Sabiston Textbook of Surgery, 21st edition (2022) — Small Intestine

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.