Clinical history: 50 year old female with diarrhea, 5-8 bowel movements per day, abdominal pain, lasting > 1 year.
Questions: What is the diagnosis, the main differential, and pathological features that help to distinguish between the two?
What is the most probable diagnosis?
Clinically, Crohn's disease and ulcerative colitis can have very similar presentations. In these cases endoscopy and histology can be helpful to distinguish between the two. Both diseases are treated similary with immunosuppression. If surgery is contemplated, however, it is important to distinguish between the two, as total colectomy with ileal pouch can be curative in ulcerative colitis, while this same procedure is associated with a high complication rate in Crohn's colitis.
Crohn's disease is characterized by trans-mural involvement, which explains several other features of Crohn's disease, such as creeping fat, stiff and thickened colonic wall, deep fissures, propensity for fistula formation and stricture formation. All of these features are uncommon in ulcerative colitis, which shows more superficial involvement.
Crohn's disease is also characterized by patchy involvement of the colon, and possible involvement of the entire GI tract. The ulcers can show abrupt transition to adjacent normal colon (aphthous ulcer). In ulcerative colitis the colon is involved diffusely, with the disease extending from the rectum proximally without skip areas.
In this case, a key diagnostic feature is the presence of well formed granulomas, which are seen in approximately 35% of cases of Crohn's disease, but are not found in ulcerative colitis. The patchy involvement is also evident, with some biopsy fragments uninvolved, some completely involved, and some showing focal inflammation with abrupt transition to adjacent normal colon.