Microaggregate of immunostained macrophages in noninflamed gastroduodenal mucosa: A new useful histological marker for differentiating Crohn's colitis from ulcerative colitis

OBJECTIVE: In 10% of cases it may be difficult to differentiate Crohn's col itis from ulcerative colitis. Distinguishing the two conditions is importan t because they are distinct entities with different therapeutic implication s. Noncaseating,granulomas are usually considered diagnostic of Crohn's dis ease. We previously reported that the presence of a microaggregate of immun ostained macrophages within the noninflamed gastroduodenal mucosa was a cha racteristic finding of Crohn's disease. The aim of this study was to determ ine whether a microaggregate of immunostained macrophages can be a reliable marker for differentiating Crohn's colitis from ulcerative colitis. METHODS: We investigated the presence of microaggregates of immunostained m acrophages and epithelioid cell granulomas in biopsy specimens taken from t he noninflamed gastroduodenal mucosa of 22 known Crohn's colitis patients a nd 23 established ulcerative colitis patients. The incidence of microaggreg ates and granulomas was compared between these two groups. RESULTS: Microaggregates and granulomas were detected only in the Crohn's c olitis patients. In addition, the presence of microaggregates was more freq uent than that of granulomas in Crohn's colitis patients (54.5% and 18.2%, respectively, 95% confidence interval for the difference: 10.0-62.7%). CONCLUSION: Detecting a microaggregate of immunostained macrophages in a bi opsy specimen taken from noninflamed gastroduodenal mucosa seems to be a us eful method for differentiating Crohn's colitis from ulcerative colitis. (C ) 2000 by Am. Cell. of Gastroenterology.