Although Crohn's disease may affect any part of the gastrointestinal tract, the most common sites are the ileum and the colon. Gross involvement of the upper gastrointestinal tract only occurs in a minority of patients (1–5%). In this subgroup, some patients do not have evidence of distal Crohn's disease at the time of diagnosis but almost all develop distal disease with the passage of time. Symptoms of gastroduodenal Crohn's disease include dyspepsia, epigastric pain, early satiety, nausea and vomiting. The endoscopic and radiological features of gastroduodenal Crohn's disease are similar to those of more distal disease and include irregular mucosal thickening, a nodular (cobblestone) mucosa, multiple aphthous ulcers, linear ulcers and duodenal strictures. Histological evaluation of endoscopic biopsies reveals a chronic inflammatory infiltrate that sometimes includes the presence of granulomas (10–30%). Medical therapy is identical to that for distal Crohn's disease although some patients may be given a trial of drugs which suppress gastric acid secretion. Surgery is only occasionally required for complications such as duodenal strictures and gastroduodenal fistulae.

The patient illustrated below was a 17-year-old woman who was investigated because of abdominal pain and diarrhea. Upper gastrointestinal endoscopy revealed notches in the duodenal folds (Fig. 1). After spraying the area with a solution of indigo carmine dye, several aphthous ulcers were identified in a longitudinal, ‘skip’ pattern (Fig. 2). Endoscopic biopsies only revealed non-specific inflammation. Colonoscopy revealed numerous aphthous ulcers in the sigmoid colon while a barium study showed longitudinal ulcers in the ileum. Non-caseating granulomas were identified in the colonic biopsies. The case illustrates the potential use of endoscopic dyes to facilitate the diagnosis of mild forms of Crohn's disease.