Primary Small Bowel Adenocarcinoma Presenting with Duodenal Stricture and Hepatic and Gastroduodenal Artery Encasement: A Case Report.

Primary small bowel adenocarcinoma is rare, with an estimated U.S. annual incidence of 3.9 cases per million persons, and is often associated with a poor prognosis. We report a case of a 68-year-old male diagnosed with primary duodenal adenocarcinoma with hepatic artery and gastroduodenal artery encasement. The patient initially presented with persistent nausea and vomiting unresponsive to ondansetron and metoclopramide, and initial computed tomography (CT) of abdomen and pelvis revealed significant stomach distension concerning for gastric outlet obstruction. Esophagogastroduodenoscopy (EGD) revealed significant duodenal stricture, with results of triple phase CT of pancreas significant for tissue encasing the common hepatic artery and the origin of the gastroduodenal artery. Pathology results verified the presence of a moderately differentiated adenocarcinoma involving the small bowel. Due to artery encasement by the tumor, the patient was deemed to be a poor surgical candidate, and instead received a duodenal stent for symptomatic relief with initiation of a chemotherapy regimen consisting of folinic acid, oxaliplatin, and fluorouracil (FOLFOX) as an outpatient. This case highlights the presentation and diagnostic workup of a rare cancer.