gastrointestinal stromal tumour

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gastrointestinal stromal tumour

A mesenchmal tumour consisting of malignant spindled cells, which affects patients above age 50. GISTs are common in the stomach and thought to arise in the interstitial cells of Cajal in the muscularis propria.

Gastrointestinal stromal tumour
1–4%—Oesophagus (leiomyoma more common).
60%—Stomach.
4%—Duodenum.
30%—Jejunum/ileum.
<1%—Colon (leiomyoma/sarcoma more common).
<<1%—Appendix.
2–4%—Rectum/anorectum.

Extragastrointestinal GIST
• Omentum;
• Mesentery.

Pathogenesis GIST
85–90%—c-KIT (tyrosine kinase receptor; activation favours proliferation) mutations.
5%—GISTs PDGFRA (platelet derived growth factor receptor alpha, a c-KIT homologue) mutation.
5%—GISTs Wild type, neither mutation.
 
Clinical findings
Symptoms are nonspecific and include bleeding, abdominal pain, nausea, vomiting and weight loss.

Adverse prognostic features
Epithelioid type, nuclear atypia, high mitotic count, necrosis, large size, non-gastric location, mucosal invasion, invasion of other organs, metastasis; possible other factors include Ki-67 labelling index, p53 overexpression, p16 loss, KIT mutation, PDGFRA mutation.
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