GI Radiography

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Imaging Findings:

Study reveals an exophytic gastric mass, with ascites and peritoneal deposits.

Diagnosis:

Gastrointestinal stromal tumors (GIST) are mesenchymal tumors which typically arise in association with the muscularis propria of gastrointestinal (GI) tract wall. They are most frequent in the stomach (60%), but also can occur in the small bowel (30%) or elsewhere, including the colon and rectum (5%), esophagus (<5%). In addition, GIST may occur as a primary tumor of the omentum, mesentery or retroperitoneum. They account for 1-3 % of gastric neoplasms, 20% of small bowel tumors and 0.2-1% of colorectal tumors. These tumors arise pathologically from the wall of the gastrointestinal tract and can be characterized as benign, borderline, low or high malignant potential based on the pathologic appearance.

GIST are a subset of a more broad category of mesenchymal tumors of the gastrointestinal tract which also includes leiomyomas, leiomyosarcomas, and schwannomas. In the past, this group of tumors had been regarded as smooth muscle tumors, but with the development of more specific diagnostic techniques, GIST are believed to display differentiation along the lines of interstitial cells of Cajal

CT plays an important role for the diagnosis and staging of these neoplasms as CT can identify the tumor and assess for local spread or distant metastases.

CT APPEARANCE

GISTs can occur anywhere in the GI tract from the esophagus to the rectum, as well as the omentum, mesentery, and retroperitoneum. The majority of GISTs appear to be well-defined, extraluminal or intramural masses with varying attenuation based on size. Small tumors tend to appear homogeneous. The larger tumors ( > 6 cm) frequently show central areas of necrosis or hemorrhage. Central gas and mural calcification are uncommon findings. Gastric GISTs commonly demonstrate extension into the gastrohepatic ligament, gastrosplenic ligament, and lesser sac, and frequently, the bulk of the tumor is seen in an extragastric location. The majority show peripheral enhancement.

Reference

http://www.ctisus.org/rsna_2004/gastric_path/articles/article3.html

Dr. Nikhil Cunha, Mumbai