CT imaging features of extragastrointestinal stromal tumor in the mesentery

Objective: To review the CT features of extragastrointestinal stromal tumor (EGIST) in the mesentery. Methods: The clinical records and CT of 15 patients with histologically confirmed EGIST in the mesentery were retrospectively studied. Results: Of the 11 high-risk EGISTs and 4 intermediate-risk EGISTs, metastasis was observed in the liver (1), abdominal cavity (1), right lower abdomen and pelvis (2), around the descending duodenum (3), mesentery root (4), left lower abdominal mesentery (4), or right pelvis (2). The mean tumor size was 11.5 cm (5.6-22.0 cm). The tumor was round with well-defined boundary (6) or irregular with poor-de-fined boundary (9). Unenhanced CT showed heterogeneous density with cystic-necrotic components in all 15 masses with calcification (2) or hemorrhage (1). The solid components showed progressive mild to moderate enhancement with CT values of 22-32 HU in the arterial phase and 38-40 HU in the venous phase. The cystic-necrotic components did not enhance. Maximum intensity projection (MIP) helped to clarify tumor blood supply by the superior mesenteric artery in 6 tumors with stripe-like and clustered vessels. Conclusion: EGIST in the mesentery has characteristic CT features. MIP can help clarify the tumor blood supply for preoperative evaluation. (authors)