Granulomas of the gut in Crohn's disease

To investigate the distribution of granulomas in Crohn's disease, a step sectioning study of the surgically resected intestines was carried out. This study proved that granulomas in Crohn's disease are found in the seemingly uninvolved intestinal mucosa as well as in the affected mucosa. Granulomas in the apparently involved mucosa were close to the mucosal surface (less than 500 μm) and small (80 to 160 μm across), while in the affected mucosa they were farther away from the mucosal surface (more than 500 μm) and larger (more than 160 μm across). We emphasize that these small granulomas, namely microgranulomas, in the apparently uninvolved intestinal mucosa, are of great value in diagnosing Crohn's disease.