What are the histologic findings characteristic of Crohn disease (CD)?

Updated: Oct 17, 2017
  • Author: William A Rowe, MD; Chief Editor: BS Anand, MD  more...
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Answer

Because biopsy specimens obtained at colonoscopy are generally superficial mucosal samples, the pathologist may have difficulty making a definitive diagnosis of ulcerative colitis or Crohn disease based on histologic findings alone. However, histology also helps rule out other causes of inflammation, including infectious colitis and ischemic colitis. The characteristic pattern of inflammation in Crohn disease is a transmural involvement of the bowel wall by lymphoid infiltrates that contains sarcoidlike granulomas in about half of the cases (most commonly in the submucosa). Also characteristic are proliferative changes in the muscularis mucosa and in the nerves scattered in the bowel wall and myenteric plexus. In the involved foci of the small and large bowel, Paneth cell hyperplasia is frequent and areas of pyloric metaplasia may be seen. In full-blown cases, long and deep fissurelike ulcers form. (See the following images.)

Deep knifelike, fissuring, transmural ulcer in Cro Deep knifelike, fissuring, transmural ulcer in Crohn disease.
Granuloma in the mucosa in a Crohn disease patient Granuloma in the mucosa in a Crohn disease patient.
Colonic granuloma in a patient with Crohn disease Colonic granuloma in a patient with Crohn disease (arrow). Hematoxylin-eosin staining. Courtesy of Dr E. Ruchelli.
A crypt abscess demonstrating active, neutrophilic A crypt abscess demonstrating active, neutrophilic inflammation in Crohn disease.

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