Which statement best describes differences between Crohn's disease and ulcerative colitis?

Which statement best describes differences between Crohn's disease and ulcerative colitis?

• A. Crohn's disease is transmural with skip lesions; ulcerative colitis has continuous mucosal inflammation starting in the rectum.
• B. Crohn's disease affects only the colon; ulcerative colitis affects the small intestine.
• C. Crohn's disease is transmural with skip lesions; ulcerative colitis involves continuous mucosal inflammation starting in the rectum.
• D. Crohn's disease never involves granulomas; ulcerative colitis always has granulomas.

Answer: (A)

The main concept being tested is how the pattern and depth of inflammation differ between Crohn's disease and ulcerative colitis. Crohn's disease characteristically shows transmural inflammation, meaning the entire bowel wall is involved, and it tends to occur in patches separated by normal tissue—skip lesions. It can affect anywhere in the GI tract, from mouth to anus. Ulcerative colitis, on the other hand, involves only the mucosa and submucosa of the colon, and it presents as a continuous inflammatory process starting at the rectum and extending proximally without skipping areas. This combination—transmural disease with skip lesions for Crohn's and continuous mucosal inflammation starting in the rectum for ulcerative colitis—best captures the classic differences between the two conditions. The other statements are less accurate because Crohn's is not limited to the colon, ulcerative colitis is not a small intestine disease, and while Crohn's can have granulomas, they are not a defining, universal feature.

The main concept being tested is how the pattern and depth of inflammation differ between Crohn's disease and ulcerative colitis. Crohn's disease characteristically shows transmural inflammation, meaning the entire bowel wall is involved, and it tends to occur in patches separated by normal tissue—skip lesions. It can affect anywhere in the GI tract, from mouth to anus. Ulcerative colitis, on the other hand, involves only the mucosa and submucosa of the colon, and it presents as a continuous inflammatory process starting at the rectum and extending proximally without skipping areas.

This combination—transmural disease with skip lesions for Crohn's and continuous mucosal inflammation starting in the rectum for ulcerative colitis—best captures the classic differences between the two conditions. The other statements are less accurate because Crohn's is not limited to the colon, ulcerative colitis is not a small intestine disease, and while Crohn's can have granulomas, they are not a defining, universal feature.