PATCHINESS OF MUCOSAL INFLAMMATION IN TREATED ULCERATIVE-COLITIS - A PROSPECTIVE-STUDY

Conventional wisdom dictates that ulcerative colitis affects contiguou s areas of the colon and is most severe in the rectum, and that the fi nding of rectal sparing or patchy involvement should raise suspicions of Crohn's disease. We and others have noted occasional rectal sparing and patchy involvement in patients with ulcerative colitis. Therefore , we prospectively studied the prevalence of patchiness, including rec tal sparing, in treated cases of ulcerative colitis. Consecutive patie nts with longstanding ulcerative colitis were studied. The left colon was divided into three zones for scoring degree of activity, and biops y specimens from each zone were graded for histologic activity by a bl inded observer. Patchiness by endoscopy or histology was defined as (1 ) frank rectal sparing (normal appearance endoscopically; absence of i nflammation of the lamina propria and crypts histologically); (2) area s of greater inflammation proximally than distally; or (3) discrete ar eas of patchiness endoscopically within any one zone. Of 39 patients e valuated, 17(44%) had endoscopic evidence of patchiness, including 5(1 3%) with rectal sparing. Thirteen (33%) had histologic evidence of pat chiness, including 6(15%) with rectal sparing. Both endoscopic and his tologic patchiness were seen in 9 patients (23%). The patchy and nonpa tchy groups did not differ in regard to the use of rectal therapy. In patients with treated ulcerative colitis, the finding of rectal sparin g or patchiness should not necessarily indicate a change in the diagno sis to Crohn's disease.