A 65-year-old man is evaluated in the clinic due to several months of abdominal pain and vomiting. The pain starts 2 to 3 hours after meals, is characterized as crampy, and is often associated with bilious vomiting. Lately, the patient has been tolerating only liquids and has consequently lost 12 lbs in the past 4 months. On physical examination, he has mild epigastric tenderness on deep palpation. Contrast-enhanced CT scan of the abdomen shows an irregular mass in the third portion of the duodenum that is infiltrating beyond the gut wall. If this mass continues to enlarge, which of the following structures is most likely to be compromised in this patient?

Question

A 65-year-old man is evaluated in the clinic due to several months of abdominal pain and vomiting.  The pain starts 2 to 3 hours after meals, is characterized as crampy, and is often associated with bilious vomiting.  Lately, the patient has been tolerating only liquids and has consequently lost 12 lbs in the past 4 months.  On physical examination, he has mild epigastric tenderness on deep palpation.  Contrast-enhanced CT scan of the abdomen shows an irregular mass in the third portion of the duodenum that is infiltrating beyond the gut wall.  If this mass continues to enlarge, which of the following structures is most likely to be compromised in this patient?

Quizplus · Accepted Answer

11ec160b_357f_9eca_9249_23aa303c29ce_MD0001_00 The first part of the duodenum emerges from the pylorus of the stomach and is horizontally oriented over the first lumbar vertebra. It is the only part of the duodenum that is not retroperitoneal. The second part of the duodenum courses inferiorly from the level of L1 to L3. This part of the duodenum is in close relation to the head of the pancreas and contains the ampulla of Vater, the site where pancreatic and common bile duct secretions are released. The third part of the duodenum courses horizontally over L3, the abdominal aorta, and the inferior vena cava. It is in close association with the uncinate process of the pancreas and the superior mesenteric artery and vein. Small bowel malignancies are rare; if they occur in the third part of the duodenum, anterior tumor invasion could compromise the superior mesenteric vessels. The fourth part of the duodenum courses superiorly and to the left of the L2 and L3 vertebrae and becomes the jejunum past the ligament of Treitz. (Choice A) The common bile duct is formed when the common hepatic duct and cystic duct join in the porta hepatis region of the hepatoduodenal ligament. The common bile duct courses inferiorly, posterior to the first part of the duodenum and within the head of the pancreas, to drain into the second part of the duodenum. (Choice B) The gastroduodenal artery arises from the common hepatic artery and courses inferiorly, posterior to the first part of the duodenum, where it then splits into the anterior superior pancreaticoduodenal artery and the right gastroepiploic artery. Peptic ulcers involving the posterior duodenal bulb can erode into the gastroduodenal artery and cause bleeding. (Choice C) The portal vein is formed by the union of the superior mesenteric and splenic veins in the retroperitoneum. It is located posterior to the pancreas at the level of the first lumbar vertebra and makes no contact with the duodenum. (Choice E) The left ureter has no relation to the duodenum. The right ureter courses retroperitoneally, posterior to the second part of the duodenum, for a short length. Educational objective: The third part of the duodenum courses horizontally across the abdominal aorta and inferior vena cava at the level of the third lumbar vertebra. The superior mesenteric vessels lie anterior to the duodenum at this location. __________ References: Upper gastrointestinal bleeding due to superior mesenteric artery to duodenum fistula: rare complication of metastatic lung carcinoma. (http://www.ncbi.nlm.nih.gov/pubmed/2039005)

A 65-Year-Old Man Is Evaluated in the Clinic Due to Several