Endoscopy — Ulcerative Colitis with Pseudopolyps

A 34-year-old woman with an 11-year history of ulcerative colitis presents with a 6-week flare characterized by 8 bloody stools per day, weight loss, and elevated inflammatory markers (CRP 62, fecal calprotectin 2,400). Ileocolonoscopy reveals the pattern marked **A** in the diagram: continuous inflammation from the rectum with loss of normal vascular pattern, friability, contact bleeding, and scattered inflammatory pseudopolyps. The terminal ileum is normal. Biopsies confirm ulcerative colitis without dysplasia. Based on the endoscopic findings at location **A**, which of the following best describes the key distinguishing feature of ulcerative colitis compared to Crohn disease?