The granuloma in Crohn's disease.

The number of granulomas in sections of bowel involved by Crohn's disease has been counted and related to length of previous history, treatment with steroids, site of involvement, and the subsequent course of the disease. It was found that a high content of granulomas predicted a good prognosis in the large bowel and anus, but was of no prognostic significance in the small bowel. A large regional variation in granuloma counts was observed from an average of 1 per section in the small bowel to 6 in the colon, 18 in the rectum, and 36 in the anus. Those patients with a long clinical history showed a low granuloma content. The findings are consistent with the view that the granuloma represents an adaptive mechanism for the removal or localisation of the causative agent of Crohn's disease.