Which patterns differentiate ulcerative colitis from Crohn disease in the colon mucosa?

Which patterns differentiate ulcerative colitis from Crohn disease in the colon mucosa?

• A. UC: continuous mucosal inflammation, crypt abscesses, mucosal atrophy, loss of haustra; Crohn: transmural inflammation, skip lesions, granulomas.
• B. UC: transmural inflammation and granulomas; Crohn: mucosal-only inflammatory changes with crypt abscesses.
• C. UC: granulomas present; Crohn: mucosal atrophy and crypt abscesses.
• D. UC: fistulas; Crohn: mucosa with mucous plaques only.

Answer: (A)

In the colon, where ulcerative colitis and Crohn disease differ most clearly is the depth and pattern of involvement. Ulcerative colitis stays limited to the mucosa (and submucosa) with continuous, uniform inflammation starting at the rectum and spreading contiguously. That mucosal inflammatory process often shows crypt abscesses—neutrophils filling the crypts—and over time leads to mucosal atrophy and loss of haustra, giving a smooth “lead-pipe” appearance. Crohn disease, by contrast, typically involves the entire wall (transmural) and can affect any segment with noncontiguous, patchy involvement known as skip lesions; granulomas may be present in the mucosa or deeper layers and complications like fistulas or strictures arise from the deeper inflammation. That’s why the best description is the one that labels ulcerative colitis as continuous mucosal inflammation with crypt abscesses, mucosal atrophy, and loss of haustra, while Crohn disease is described as transmural inflammation with skip lesions and granulomas. Other options mix these features incorrectly—for example, attributing transmural inflammation and granulomas to ulcerative colitis, or describing Crohn disease as mucosal-only inflammation with crypt abscesses, or suggesting fistulas belong to ulcerative colitis. Those mismatches don’t align with the characteristic patterns used to distinguish the two in colon mucosa.

In the colon, where ulcerative colitis and Crohn disease differ most clearly is the depth and pattern of involvement. Ulcerative colitis stays limited to the mucosa (and submucosa) with continuous, uniform inflammation starting at the rectum and spreading contiguously. That mucosal inflammatory process often shows crypt abscesses—neutrophils filling the crypts—and over time leads to mucosal atrophy and loss of haustra, giving a smooth “lead-pipe” appearance. Crohn disease, by contrast, typically involves the entire wall (transmural) and can affect any segment with noncontiguous, patchy involvement known as skip lesions; granulomas may be present in the mucosa or deeper layers and complications like fistulas or strictures arise from the deeper inflammation.

That’s why the best description is the one that labels ulcerative colitis as continuous mucosal inflammation with crypt abscesses, mucosal atrophy, and loss of haustra, while Crohn disease is described as transmural inflammation with skip lesions and granulomas.

Other options mix these features incorrectly—for example, attributing transmural inflammation and granulomas to ulcerative colitis, or describing Crohn disease as mucosal-only inflammation with crypt abscesses, or suggesting fistulas belong to ulcerative colitis. Those mismatches don’t align with the characteristic patterns used to distinguish the two in colon mucosa.