The relationship between inflammatory and serosal connective tissue changes in ileal Crohn's disease: evidence for a possible causative link.

The relationship between the gross connective tissue and inflammatory changes in ileal Crohn's disease remains unclear. This study investigated 20 patients undergoing ileal resection for Crohn's disease and 20 normal controls. The specimens were blocked in 1 cm serial sections and fully examined, including fresh morphometry and documentation of a range of pathological features. Pathological features of disease showed uniform distributions within affected segments, although specimens showed different patterns and severity of affliction. Serosal fat wrapping (FW) was present in all cases and was significantly greater than normals [mean 63.5% (SD 27. 8) vs. 21.0% (6.4), p<0.001], as was mesenteric thickening (MTh) [mean 18.0 mm (SD 11.1) vs. 5.9 mm (2.2), p<0.001]. The extent of FW correlated significantly with the degree of acute and chronic inflammation (r()=0.32 and 0.23 respectively, p<0.01), particularly the extent of transmural inflammation in the form of lymphoid aggregates (r()=0.35, p<0.01). MTh did not correlate with any features studied. These findings support the hypothesis that serosal connective tissue changes in Crohn's disease are related to the local effects of underlying chronic inflammatory infiltrates. Full thickness, radial samples from a grossly affected area are representative of the histopathological features present in a diseased segment as a whole.