GASTROINTESTINAL STROMAL TUMOR (GIST)

Question 1

Definition (5)

Answer 1

1- Most common type of stromal or mesenchymal tumors of gastrointestinal tract
2- Occurs most commonly in the stomach and proximal small intestine
3- They were previously considered benign, but on prolonged follow up, MOST have malignant potentials, they are slow growing tumors
4- Usually asymptomatic, however they may ulcerate and bleed
5- May be discovered incidentally when an upper endoscopy is done for dyspepsia

Question 2

Histology

Answer 2

3 subtypes: spindle (most common), epitheloid, and mixed/pleomorphic

Question 3

GIST

Answer 3

G: gastric, genes: cKIT (CD117), PDGFRA (mutations inherited at AD fashion)
I: Interstitial cells of Cajal
S: spindle cells, submucosal mass
T: tyrosine kinase receptor

Question 4

Treatment (2)

Answer 4

1- Surgical resection with negative margins
2- Imatinib (tyrosine kinase inhibitor) used in advanced stages (unresectable/metastatic) and as adjuvant treatment after resection