We’re lead to believe that Ulcerative Colitis (UC) always presents in the same way, which is continuous and only in the colon, so I am here to clear this “fact” up.
The excerpts below are taken from BSG guidelines on inflammatory bowel disease biopsies. This is a 22 page document which you can download and read! I have added a few explanations for the medical jargon within the text to make this easier to understand!
Although UC is typically continuous between anatomical sites, there are various exceptions to the rules. The caecum (pouch connected to the junction of the small and large intestines) may show changes reminiscent of UC despite an uninvolved adjacent colon (caecal patch). Also, there may be apparent rectal sparing endoscopically or in biopsies (though not in resections). These phenomena do not change the diagnosis but should lower the threshold for considering Crohn’s Disease (CD). ‘Appendiceal UC’ may be discontinuous with colonic disease (‘skip’ lesion). Longstanding and/or treated UC may be distributed unevenly between sites, within sites, and within biopsies. (Pg 7)
Extent and distribution can also vary with time and treatment. Rectal sparing, discontinuity between sites, and patchy or focal changes within sites are recognised features of longstanding UC. (Pg 13)
Upper gastrointestinal involvement
Occasionally, there is distal terminal ileal inﬂammation in UC. Despite being attributed to ‘backwash’, it is not always accompanied by caecal involvement. Villous atrophy (when your intestinal villi —the microscopic, finger-like tentacles that line the wall of your small intestine—erode away), mixed lamina proprial inﬂammation, cryptitis, crypt abscesses and focal erosion may be seen. Pyloric metaplasia (mucous gland metaplasia) can occur, but is not common.
Duodenal involvement is not uncommon in CD but is also seen in a few UC patients whose biopsies may show a pattern of diffuse chronic inﬂammation and crypt changes resembling the colorectal abnormalities. ‘Focally enhanced gastritis’, characterised by a focal mixed perifoveolar/periglandular inﬂammatory inﬁltrate with epithelial damage, was ﬁrst reported as a feature of CD, but is not speciﬁc, and can also be seen in UC.
Upper gastrointestinal involvement by UC may be more common in children than in adults. (pg 13)