Background: While terminal ileitis is most often associated with Crohn’s disease, it has a broad differential, including malignancy. Case Presentation: We report an 83-year-old female with fever and right lower quadrant abdominal pain. An imaging study revealed an abscess located at a thickened terminal ileum. The etiology of terminal ileitis was unclear, but symptoms subsided with antibiotics and cessation of naproxen. Two years later, the patient presented with similar symptoms and imaging findings. Colonoscopy revealed a submucosal mass, which was found to be adenocarcinoma, located in the cecum and terminal ileum. Conclusion: This case highlights that differential for cecal adenocarcinoma with extension into the terminal ileum should be considered in those presenting with terminal ileitis and abscess formation.

Keywords: Cecal adenocarcinoma, terminal ileitis, abscess, diagnostic challenge.