Atlas of Gastroenterological Endoscopy
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Gastrointestinal stroma tumors (GIST) - in general
GIST are rare mesenchymal tumors of the gastrointestinal tract (nerve tissue and smooth muscle). They originate propably from mesenchymal stem cells with a potential to differentiate. In the classification of GI-tract tumors they are a relatively new entity.Histology and Immunhistochemistry discriminate gastrointestinal stroma tumors from leiomyomas and neurinomas. The most important location is the stomach. Usually classic signs of malignancy (cellular invasion, metastasis) are missing, but a set of histological criteria decides whether the tumor should be classified as malignant or benign (mitotic activity, cellular pleomorphism, developmental stage of the cell and quantity of cytoplasma). Tumors with a high mitotic activity and a size above 5 cm are considered to be malignant. Recent pharmacological advances (Thyrosine kinase inhibitors) have determined c-kit (i.e. CD117) the most important marker. C-kit positive tumors respond extremely well to chemotherapy.
Gastrointestinal Stroma Tumor (GIST) with arterial hemorrhage
GIST GIST
Arterial hemorrhage (Forrest Ia) from an ulcer on top of a submucous tumor of the gastric body. The hemorrhage is successfully treated by injection of 3 ml of a fibrin- adhesive. A fibrin string swings from the tumor into the gastric cavity.
GIST The tumor measures 4 cm in diameter. The mucosa as such shows no pathological changes underlining the submucous location of the tumor by means of endoscopy.
Surgery shows the tumor at the dorsal wall of the gastric body with the ventral wall opened up by incision. Two superficial ulcers are seen. The lower one is supposed to be the site of the former hemorrhage. Histology reveals a gastrointestinal stroma tumor (GIST, subtype of a leiomyoma) with a low mitotic activity.
  • eröffnete Magenvorderwand = ventral gastric wall opened up by incision
  • Magenhinterwand = dorsal gastric wall
  • Ulkus alt/frisch = Ulcer old/ recent
  • Längsgastrostomie Korpusmitte = vertical median gastrostomy of the body
GIST
GIST, borderline malignant potential
GIST Tumor of the gastric body more than 5 cm in size. The mucosa presents normal except a little erythematous. The yellow colour shining through the mucosa raises the suspicion of a lipoma. A button- whole biopsy fails to establish the diagnosis. Histologic work- up of the surgical resection specimen demonstrates a GIST with borderline malignant potential. (tumor size, vimentin-, MIB1- and desmin positivity).
GIST with ulcerations
GIST with ulcer GIST with ulcer
Ulcerations and hemorrhages (see above) do frequently occurr, owing to the extensive vascularisation of these tumors.