Clinical Presentation

A 20-year-old man presents with a 1-year history of abdominal pain and diarrhea.

(A) Coronal reformatted infused computed tomography (CT) shows marked mural thickening of the distal small bowel (arrows) with a three-layer density pattern, consistent with the “fat halo” sign. In addition, there are dilatation and separation of the vasa recta of this segment along the mesenteric side, consistent with the “creeping fat” or “comb” sign. (B) Small-bowel follow-through shows a “cobblestone” appearance of barium (arrows) within the terminal ileum and an adjacent stricture (“string” sign).

Differential Diagnosis

• Crohn disease: