Idiopathic localized dilatation of the ileum.

A 72-year-old man was noted to have an abdominal mass during a health check-up. Computed tomography showed a large cyst-like structure in the right subhepatic space (white arrowheads) that had continuity with the proximal and distal ileal loops. The wall of the structure showed the same enhancement pattern as the adjacent ileal loops, which suggested that the lesion was a part of the ileum (Picture 1). A small bowel series showed the presence of a saccular dilated segment of the ileum (black arrowheads) measuring 10.5× 8.0×6.7 cm (Picture 2). The resected specimen showed a localized dilated ileal loop without valvulae conniventes. Two abrupt transitional points (white arrows) to the adjacent ileal loops were found (Picture 3). When one sees a sharply demarcated cystic lesion with a bowel-like layered enhance-