What causes collar button ulcer in the gastrointestinal tract on radiographic imaging?
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The collar button ulcer is caused by mucosal ulceration with undermining submucosal extension limited by the relatively resistant muscularis propria of the gastrointestinal tract wall. It is most commonly associated with inflammatory diseases such as ulcerative colitis, particularly in advanced acute stages. It may also appear transiently in other ulcerating inflammatory diseases affecting the GI tract, including infectious and granulomatous conditions.
Why is it called so?
The name “collar button ulcer” arises from the distinctive radiographic imaging appearance of the ulcer, which resembles a collar button. This shape results from a small mucosal defect with a broader undermined submucosal base, producing a flask-like or collar-stud configuration.
Pathophysiology
The ulcer begins as mucosal damage that extends laterally beneath intact mucosa into the submucosa, limited by the muscularis propria, creating an undermined base wider than the mucosal opening. This undermining leads to the button-like shape on imaging. The process reflects ongoing inflammatory destruction predominantly involving mucosa and submucosa, with adjacent relative muscular wall preservation, characteristically seen in ulcerative colitis and other inflammatory colitides.
Alternative names: Collar-stud ulcer
Other associated named signs: In ulcerative colitis, additional signs include pseudopolyps, mucosal stippling, lead pipe colon, and thumbprinting.
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