A 46-year-old woman was first examined 14 years ago for a history of bloody diarrhea. A diagnosis of ulcerative colitis was made. The disease had been in remission for most of the time since then. It recurred in July 1974, when she again had multiple loose stools containing blood. She also complained of a dull ache in the right iliac fossa. On examination, a small, vague, slightly tender mass was palpable there. A plain film on the abdomen showed no abnormality. Figures 1 and 2 were made during barium enema examination.
Mucocele of the appendix.
The characteristic roentgenographic appearance of a round, welldefined filling defect in the cecum with nonfilling of the appendix enabled the correct preoperative diagnosis to be made. The small, round, translucent area about 4 mm in diameter visible in the center of the larger mass represented the proximal end of the appendix, which