THE RELATIONSHIP OF GRANULOMAS TO BLOOD-VESSELS IN INTESTINAL CROHNS-DISEASE

It has been suggested that granulomatous vasculitis is a primary mecha nism in the production of pathologic changes seen in Crohn's disease. We set out to investigate the relationship of granulomas to blood vess els and to confirm or refute previous reports of granulomatous vasculi tis in Crohn's disease. Thirty paraffin embedded tissues from 11 patie nts with Crohn's disease were selected after examination of H&E staine d sections for the presence of granulomas. Using an immunohistochemica l method, various monoclonal antibodies were applied to sequential sec tions from each tissue to demonstrate vascular structures and granulom as. In three patients none of the granulomas occurred in association w ith blood vessels, in five a small proportion of the granulomas affect ed blood vessels, and in three granulomatous vasculitis appeared occlu sive and significant. A total of 232 granulomas were identified, 22% o f which were closely associated with blood vessels, which included bot h arteries and veins; 16% were perivascular, while 6% were intravascul ar. Perivascular granulomas did not surround blood vessels or invade t he medial layers. They were asymmetric, suggesting that they originate d by encroachment of nearby lymphatic or connective tissue granulomas. These results indicate that the granulomas of Crohn's disease are usu ally not associated with blood vessels; however, there is a minority o f patients in whom vascular granulomatous inflammation may be importan t, although probably as a secondary phenomenon.