An Unexpected Challenge: Marked Small Bowel Obstruction Arising From a Poorly Differentiated Metastatic Mucinous Adenocarcinoma of the Distal Ileum in a Risk-Free Healthy Patient.

Adenocarcinoma, while constituting the predominant variant among small bowel cancers, is a component of the broader category of primary small bowel malignancies, which are notably infrequent in occurrence. The diagnosis of such malignancies is often markedly delayed, a consequence of their insidious onset and the nonspecific nature of the abdominal symptoms presented. A 69-year-old Caucasian male presented to the emergency department manifesting acute, sharp, and colicky abdominal pain accompanied by a single episode of vomiting, all developing over one day. His medical history was notable for gastroesophageal reflux disease (GERD) and regionally confined prostate adenocarcinoma, which was under meticulous surveillance by the urological team. The patient's lifestyle was characterized by abstention from alcohol and tobacco, adherence to a nutritious diet, and a commitment to regular physical activity. Subsequent examination and surgical excision of an abnormal mass, as delineated on computed tomography (CT), culminated in the diagnosis of a stage IV, poorly differentiated adenocarcinoma. We have reported this case to spark research regarding early diagnostic techniques for small bowel adenocarcinoma (SBA). In this case, a healthy individual presented with vague abdominal pain and a single episode of vomiting. Diagnosis required the surgical resection of the tumor, where metastasis was also visualized. Due to the rare nature of SBA, we believe different diagnostic measures and adjuvant therapy should be researched for earlier diagnosis and subsequently better patient outcomes.