Which pattern of colitis is most characteristic of ulcerative colitis?

• A. Continuous mucosal inflammation starting at the rectum
• B. Skip lesions with transmural inflammation
• C. Granulomatous inflammation with fissures
• D. Transmural involvement with fistulas

Answer: (A)

Ulcerative colitis classically shows continuous inflammation of the colon that begins in the rectum and extends proximally in a uniform, non‑skip fashion, limited to the mucosa and submucosa. This superficial, continuous pattern contrasts with Crohn disease, which typically features skip lesions with transmural involvement that can produce fistulas or fissures and may include granulomas. So the hallmark pattern—continuous mucosal inflammation starting at the rectum—best fits ulcerative colitis.