A 14-year-old girl has a 9-month history of diarrhea, periumbilical and postprandial abdominal pain, fever, and weight loss. Her menses are now irregular. She has had several episodes of blood in her stools. Which of the following is the most likely diagnosis?

The presentation of Crohn disease (granulomatous colitis) depends on the location and extent of lesions. Onset of the GI or extraintestinal symptoms can be insidious. The "textbook" presentation is as described, although only 25% of patients have the "triad" of diarrhea, weight loss, and abdominal pain. Crohn disease characteristically is associated with transmural, granulomatous intestinal lesions that are discontinuous and can appear in both the small and large intestines. Although Crohn disease can first appear as a rectal fissure or fistula, the rectum is often spared. Arthritis/arthralgia occurs in a minority of affected children. Other extraintestinal symptoms include erythema nodosum or pyoderma gangrenosum, liver disease, renal calculi, uveitis, anemia, specific nutrient deficiency, and growth failure. In relation to the general population, the risk of colonic carcinoma in affected persons is increased, but not to the degree associated with ulcerative colitis.