Small erythematous mucosal plaques: an endoscopic sign of Crohn's disease.

A non-ulcerated granulomatous lesion of the large bowel mucosa has been found in 11 patients, nine of whom already had or eventually developed classical features of Crohn's disease. These lesions, which are multiple, consist of small well-circumscribed raised erythematous plaques surrounded by normal mucosa. At biopsy there is focal haemorrhage of the lamina propria, rupture of the crypts, release of mucus, and frank granulomatous reaction with giant cell formation. The lesion may be reversible or be followed by the classical mucosal ulcerations. They may occur in the presence or the absence of classical lesions of Crohn's disease elsewhere in the gastrointestinal tract. As this non-ulcerated lesion may occur in isolation, it may provide the initial clue to the diagnosis of Crohn's disease.