Abstract Small intestinal neoplasia is a rare condition that frequently presents a diagnostic challenge. We describe the case of a 70-year-old patient who presented with several years of chronic, intermittent abdominal pain, previously diagnosed as irritable bowel syndrome. Radiographic evaluation, including upper gastrointestinal series with small bowel follow-through and computed tomography, demonstrated dilated small bowel with possible strictures. Colonoscopy and upper endoscopy were unrevealing. Attempted capsule endoscopy resulted in capsule retention. Subsequent laparoscopy led to the identification of severe, active Crohn disease with strictures, ulcers, crypt abscesses, pyloric metaplasia, and transmural inflammation. Extensive flat and polypoid high- and low-grade dysplasia were present, as well as an area of well-differentiated adenocarcinoma invading into the muscularis propria. We discuss the epidemiology, pathogenesis, and diagnosis of small bowel malignancy.