S3326 Sigmoid Colon Obstruction Secondary to Metastatic Pancreatic Adenocarcinoma: A Rare Clinical Presentation

Introduction: Pancreatic adenocarcinoma most frequently metastasizes to the liver, lungs, and adrenal glands. Metastatic involvement of the sigmoid colon is exceptionally rare, with fewer than a dozen cases documented in the medical literature. Symptomatic presentations are even more uncommon, with only 3 reported cases describing bowel obstruction secondary to pancreatic adenocarcinoma metastasis. We present a rare case of pancreatic adenocarcinoma metastasizing to the sigmoid colon, manifesting as large bowel obstruction and confirmed through histopathological analysis. Case Description/Methods: A 74-year-old man with a history of stage IV pancreatic adenocarcinoma, status post Whipple procedure, presented with 1-week history of intermittent lower abdominal pain, decreased oral intake, emesis, and absence of bowel movements. On physical examination, the abdomen was distended and tender to palpation. A computed tomography scan of the abdomen with oral contrast revealed wall thickening of the sigmoid colon, raising concern for a mass or stricture resulting in large bowel obstruction, along with findings suggestive of recurrent metastatic disease. Gastroenterology initially attempted a flexible sigmoidoscopy, which was unsuccessful due to complete luminal obstruction of the sigmoid colon. A subsequent colonoscopy was performed, during which an uncovered metal stent was placed, resulting in significant stool drainage. A suspicious mass was visualized in the sigmoid colon, and biopsies were obtained. Immunohistochemical staining of the samples was positive for CK7 and CDX2, and negative for CK20. These findings supported a diagnosis of metastatic pancreatic adenocarcinoma. Following stent placement, the patient reported relief from obstructive symptoms and was able to tolerate a liquid diet. Despite initial clinical improvement, his condition continued to decline due to extensive metastatic disease, and he ultimately expired. Discussion: This case highlights the exceptionally rare presentation of pancreatic adenocarcinoma metastasizing to the sigmoid colon. Prompt endoscopic stent placement allowed for both symptomatic relief and the opportunity to obtain tissue samples for diagnosis. Although rare, metastasis to the colon should be considered in patients with a prior history of pancreatic cancer who present with obstructive gastrointestinal symptoms. Early identification and intervention can significantly impact symptom management and quality of life.