What are the cross sectional imaging features of gastrointestinal stromal tumor (GIST)?
GIST arises from the interstitial cells of Cajal, uniquely expresses CD117, and may have benign or malignant biologic behavior. It most commonly occurs in the stomach (60%) (most often in the gastric fundus and body), followed by small bowel (25%) (usually in the jejunum), and anorectum (10%).
A focal soft tissue enhancing mass is typically seen, often with intraluminal and/or exophytic soft tissue tumor components. Small (<5 cm) lesions tend to be homogeneous, whereas large (>5 cm) lesions tend to be heterogeneous secondary to presence of hemorrhage, calcification, cystic change, and/or necrotic change. Unlike other GI tract malignancies, lymphadenopathy is very uncommon, although distant metastases (most commonly to the liver) and extension to the peritoneal cavity may be encountered