Vignette: A 34-year-old male presents to the emergency department with a 2-day history of severe, crampy abdominal pain, bloody diarrhea, and fever. He mentions that he has been having intermittent abdominal pain and diarrhea for the past 3 months. His medical history is significant for Ankylosing Spondylitis (AS) for which he has been taking NSAIDs. On physical examination, he appears to be in distress. His temperature is 38.5 C, blood pressure is 135/85 mm Hg, pulse rate is 105 beats/min, and respiratory rate is 18 breaths/min. Abdominal examination reveals diffuse tenderness with guarding. Laboratory tests show a WBC count of 15,000/mm3 and Hemoglobin of 10 g/dL. Stool culture and tests for Clostridium difficile are negative. A colonoscopy is performed which shows continuous areas of inflammation, ulcerations and pseudopolyps in the colon.
The most likely pathophysiological mechanism underlying this patient’s condition is:
A) Transmural inflammation
B) Mucosal and submucosal inflammation
C) Granuloma formation
D) Skip lesions
E) Fissures and fistula formation
B) Mucosal and submucosal inflammation
This patient's presentation of bloody diarrhea, abdominal pain, fever, and colonoscopy findings of continuous colonic inflammation with ulcerations and pseudopolyps is consistent with Ulcerative Colitis (UC). UC is a chronic inflammatory bowel disease that is characterized by relapsing and remitting mucosal and submucosal inflammation (Choice B) that typically starts in the rectum and extends proximally in a continuous manner. This is in contrast to Crohn's disease, another type of inflammatory bowel disease, which is characterized by transmural inflammation (Choice A) and can affect any part of the gastrointestinal tract in a discontinuous ("skip") pattern (Choice D) leading to complications such as fissures and fistulae (Choice E). Granuloma formation (Choice C) is also a feature of Crohn's disease but not UC. Long-term NSAID use is a risk factor for UC.
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