Which structure is likely compressed by the following tumor?
A 58-year-old man is admitted to a hospital with severe abdominal pain, nausea, and vomiting resulting in dehydration. Emergency computed tomography (CT) scan reveals a tumor located between the celiac trunk and the superior mesenteric artery.
The pyloric canal and the neck of the pancreas are situated anterior to the abdominal aorta between the origin of the celiac trunk and the superior mesenteric artery. The transverse colon passes anterior to the superior mesenteric artery and the third part of the duodenum. The other structures are not located in front of the aorta.