A 32-year-old man with abdominal pain and periodic diarrhea is found to have heme-positive stools. Stool cultures show no growth of pathogenic organisms. Colonoscopy with biopsy of the colonic mucosa is performed. Light microscopy of the tissue sample is shown in the image below. This patient most likely suffers from which of the following disorders?

Question

A 32-year-old man with abdominal pain and periodic diarrhea is found to have heme-positive stools.  Stool cultures show no growth of pathogenic organisms.  Colonoscopy with biopsy of the colonic mucosa is performed.  Light microscopy of the tissue sample is shown in the image below.  This patient most likely suffers from which of the following disorders?

Quizplus · Accepted Answer

11ec160b_3950_ca21_9249_9537877e11fa_MD0001_00 This younger patient with abdominal pain, heme-positive stool, and noncaseating granulomas (NCGs, pictured above) on microscopy has Crohn disease (CD). CD is an inflammatory bowel disease that can cause patchy inflammation throughout the gastrointestinal tract, interspersed with areas of normal bowel (skip lesions). NCGs are often seen in CD and are considered a hallmark of the disease. NCGs are characterized by an accumulation of epithelioid macrophages that frequently form multinucleated giant cells without central necrosis (noncaseating), surrounded by a cuff of lymphocytes. Granulomas are formed in an attempt to wall off an offending agent; in the case of CD this is likely due to an unregulated immune response to gut flora or self-antigens. They can be found in any layer of the intestinal wall, and may also be present in other tissues such as the lymph nodes and skin. Other characteristic histopathologic findings in CD include inflammation involving the entire thickness of the intestinal wall (transmural inflammation), distortion of normal mucosal architecture, and Paneth cell metaplasia. (Choice A) Acute appendicitis presents with periumbilical or right lower quadrant pain and fever. Microscopy shows a dense neutrophilic infiltrate and necrosis of the appendix. (Choice B) Collagenous (microscopic) colitis typically presents with frequent diarrhea in older women and histology demonstrates thickening of the subepithelial collagen band. (Choice D) Ischemic colitis is most common in older patients and presents with abdominal pain and bleeding; microscopy shows necrosis, thrombus formation, and hemorrhage. (Choice E) Pseudomembranous colitis is due to Clostridioides difficile infection and presents with watery diarrhea, abdominal pain, and fever. Microscopy shows mucopurulent exudates composed of fibrin, bacteria, and neutrophils. (Choice F) Ulcerative colitis is another cause of inflammatory bowel disease; histology demonstrates a continuous superficial inflammation affecting the mucosa and submucosa with crypt abscesses (neutrophil collections within glandular lumen) and crypt atrophy. Granulomas do not occur. Educational objective: Noncaseating granulomas are a hallmark of Crohn disease and can help distinguish it from ulcerative colitis, which does not form granulomas. Histopathology in Crohn disease also demonstrates transmural inflammation, distortion of the normal architecture, and Paneth cell metaplasia.

A 32-Year-Old Man with Abdominal Pain and Periodic Diarrhea Is