RADIOLOGY: GASTROINTESTINAL: GI: Case# 88: CARCINOID & SMV OCCLUSION. 57-year-old woman with history of diarrhea and vague abdominal pain. There is a small amount of ascites present. A large mass with stellate margins radiating into the mesentery is identified. Calcification is noted within the mass. The SMV is not visualized suggesting thrombosis. There is diffuse small bowel wall thickening and dilatation. Carcinoid is the most common primary neoplasm of the small bowel. When found in the mesentery, these tumors induce a desmoplastic response which involves a thickening and retraction of the mesenteric fat. The desmoplastic response may result in venous occlusion, such as in this case. Calcifications within these mesenteric tumors are common. The carcinoid syndrome does not occur until metastatic disease to the liver is present. Symptoms of carcinoid syndrome include nausea and vomiting, diarrhea, episodic flushing, and headache.