A 50 year old male presented with recurrent bloody diarrhea. Colonoscopy showed geographical ulcers. Histopathology is shown below. What is your diagnosis?
**Core Concept**
The patient's presentation of recurrent bloody diarrhea with geographical ulcers on colonoscopy is suggestive of an inflammatory bowel disease, specifically one that causes deep ulcers in the colon. This condition is characterized by a chronic, relapsing course and can lead to complications such as colorectal cancer.
**Why the Correct Answer is Right**
The histopathology findings, although not explicitly described, are likely to show a mixed inflammatory infiltrate with ulceration and crypt abscesses. The presence of geographical ulcers on colonoscopy is a hallmark of Crohn's disease, which can affect any part of the gastrointestinal tract from the mouth to the anus. The ulcers in Crohn's disease are typically deep and can lead to complications such as fistulae, abscesses, and obstruction. The exact mechanism behind Crohn's disease is not fully understood, but it is thought to be related to an abnormal immune response to luminal antigens, leading to chronic inflammation and tissue damage.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the histopathology or clinical presentation of Crohn's disease. While ulcerative colitis (UC) can also cause bloody diarrhea, it typically presents with continuous inflammation limited to the rectum and extending proximally in a continuous manner, unlike the geographical ulcers seen in Crohn's disease.
* **Option B:** This option is incorrect because it does not accurately describe the histopathology or clinical presentation of Crohn's disease. Ischemic colitis typically presents with acute onset of bloody diarrhea and can be caused by a variety of factors including vascular disease, medications, and hypoperfusion.
* **Option C:** This option is incorrect because it does not accurately describe the histopathology or clinical presentation of Crohn's disease. Infectious colitis typically presents with acute onset of diarrhea and can be caused by a variety of pathogens including bacteria, viruses, and parasites.
* **Option D:** This option is incorrect because it does not accurately describe the histopathology or clinical presentation of Crohn's disease. Diverticulitis typically presents with left lower quadrant pain and can be caused by a variety of factors including diverticula, foreign bodies, and inflammatory bowel disease.
**Clinical Pearl / High-Yield Fact**
The presence of geographical ulcers on colonoscopy is a key feature that distinguishes Crohn's disease from other forms of inflammatory bowel disease, including ulcerative colitis. Additionally, the presence of deep ulcers and complications such as fistulae and abscesses are also characteristic of Crohn's disease.
**Correct Answer: C. Crohn's disease**