Review Question - QID 108740

A 15-year-old boy is brought to his pediatrician for a follow-up visit. His parents report that he is doing well in school and has many friends. Their only concern is that he has a “difficult stomach.” Every few months, he complains of intermittent abdominal pain that takes several days to pass. He occasionally misses school due to the pain. There is blood in his stool during these episodes. These symptoms have persisted for many years. The parents have so far managed the condition using herbal teas and essential oils but have not sought formal medical care. His temperature is 98.2°F (36.8°C), blood pressure is 106/61 mmHg, pulse is 88/min, and respirations are 12/min. He has lost 10 pounds since his annual visit the year before and is the same height. On physical exam, the patient is thin with conjunctival pallor. His sclerae are anicteric and his abdomen is soft and non-tender without hepatosplenomegaly. He also has the findings seen in Figure A. He undergoes an abdominal CT that shows disease affecting the terminal ileum. Which of the following is most likely to be present in this patient?