system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 65-year-old man comes to the physician because of abdominal pain and bloody, mucoid diarrhea for 3 days. He has been taking over-the-counter supplements for constipation over the past 6 months. He was diagnosed with type 2 diabetes mellitus 15 years ago. He has smoked one pack of cigarettes daily for 35 years. His current medications include metformin. His temperature is 38.4°C (101.1°F), pulse is 92/min, and blood pressure is 134/82 mm Hg. Examination of the abdomen shows no masses. Palpation of the left lower abdomen elicits tenderness. A CT scan of the abdomen is shown. Which of the following is the most likely underlying cause of the patient's condition?
assistant
Focal weakness of the colonic muscularis layer