Gastrointestinal stromal tumor (GIST)

There is blood in the jenunum. A submucosal mass was seen. More bleeding started after probing the mass. Clips were placed.

Jejunal bleeding vessel at endoscopy 42 x 37 x 31 mm mildly lobulated solid vividly enhancing/hypervascular mass in the right upper quadrant abuts the loop of jejunum marked by endoscopic clips, but may be centered over mesentery. Evidence of AV shunting into a prominent vein that drains into the portal venous system. The arterial supply appears to be from a jejunal branch. No evidence of active contrast extravasation/bleeding. No surrounding stranding. No 2nd lesion. No liver lesion. Minor basal atelectasis. Conclusion Mass lesion relating to the endoscopically marked jejunum is most probably a GIST tumor, although necrosis would be commonly seen for this size. Other hypervascular differentials include carcinoid or glomus tumors. The AV shunting may be related to the tumor, or be related to the clipping.

Laparotomy and small bowel resection.
Tumor bleeding into bowel.
?GIST.

MACROSCOPIC DESCRIPTION: "Small bowel resection":  A segment of small bowel 35mm in length x 20mm in diameter with a central exophytic mushrooming serosal tumor 48x42x35mm.  Photograph taken.  Tumor surface inked blue.  Sectioning shows a pink fleshy tumor which extends into muscularis propria.  No mucosal polyps or tumors are seen.  No necrosis or hemorrhage is identified.

BLOCK DESIGNATION:

A    -  small bowel resection ends.
B-D  -  tumor including bowel wall.
E-F  -  tumor.  P6.  (TWR)

MICROSCOPIC DESCRIPTION: The sections show a circumscribed spindle cell tumor composed of intersecting fascicles.  Tumor cells have medium sized oval nuclei, fine chromatin, small nucleoli and a moderate amount of fibrillary cytoplasm.  There are occasional perinuclear vacuoles and frequent skenoid fibers.  There are scattered dilated vessels.  There are areas of granulation tissue, foamy macrophages and hemorrhage within the tumor.  The overlying serosa appears hemorrhagic.  The tumor replaces full thickness of the small bowel wall excluding the mucosa.
Focally there are ectatic vessels beneath the mucosa which focally communicate with the bowel lumen, consistent with a site of GI hemorrhage.  The overlying mucosa is otherwise unremkarkable. The sections of margins are clear of tumor.  No mitoses are identified.
By immunohistochemistry the tumor cells are C-KIT positive,  DOG1 positive, SMA negative and S100 negative.

DIAGNOSIS: Small bowel resection:

* Gastro-intestinal stromal tumor (GIST)
-  Size 48mm
-  No mitoses
-  C-KIT positive by immunohistochemistry

COMMENT: The behavior of gastro-intestinal stromal tumors is difficult to predict.  Based on the tumor location (small bowel), the size, and mitotic rate, this tumor is considered to have a low risk
of aggressive behavior (REF: DIAGNOSIS OF GASTROINTESTINAL STROMAL TUMORS (Fletcher et al), HUMAN PATHOLOGY Volume 33, No. 5 (May 2002)).