Small bowel adenocarcinoma develops in 1.5% of patients who have longstanding Crohn disease and is very rarely diagnosed preoperatively because of its rarity, overlapping imaging features, and lack of reported cases. Nonspecific findings including loss of mural stratification (i.e., "target sign") and mild degree of bowel wall enhancement when combined with enlarged mesenteric lymph nodes were helpful computed tomographic findings to suspect malignancy in our case.