A 65-year-old man presents with abdominal pain, 15-lb (6.8-kg) weight loss, rectal bleeding, diarrhea, and joint pain. He had recently started taking prednisone for rheumatoid arthritis. On endoscopy, he is noted to have mucosal friability and ulcerations with pseudopolyps in the descending colon with rectal sparing. His terminal ileum is normal. Which finding is associated with a diagnosis of Crohn’s disease?