The so-called "skip lesions" can affect any segment of the GI tract, but most commonly involve the ileum and colon, and the rectum is usually spared ("skip" refers to its discontinuous pattern).
We draw the GI tract in section to show transmural inflammation with wall thickening.
Creeping fat" that wraps around the GI tract.
Different types of lesions:
Aphthous erosions – these early signs of Crohn's disease are shallow, whitish or opaque sores in the mucous membrane.
Longitudinal, aka, rake or "bear claw" ulcers look as if someone dragged a rake down the lining of GI tract.
Eventually, the lining of the GI tract can take on a "cobblestone" appearance, as tissue becomes so crowded with ulcers that it resembles a cobblestone sidewalk.
Fissures in the wall form and can progress to form fistulas that open to abdominal/pelvic cavity or connect with other organs (such as the vagina).
As a result of chronic inflammation, fibrosis of the GI wall also occurs.
Histologically, Crohn's disease is associated with intestinal wall crypt distortion, fissures, and, in up to 60% of cases, noncaseating granuloma formation.
Crohn's disease is characterized by Th1/Th17 cell-mediated inflammation.
Signs/Symptoms:
Patients with Crohn's disease commonly complain of: Abdominal cramping (often on the right side, where the ileum meets the large intestine) Diarrhea (potentially bloody diarrhea) Fever and malaise Weight loss (due to malabsorption), Perianal lesions (25% of patients) - we show skin tags near the anus and fistulas that form in the anal canal and open to the perianal region.
Complications of Crohn's disease include problems related to fistulas, fissures, and obstructive strictures; dysplasia and adenocarcinoma; and, anemia from chronic blood loss.
Treatments: Patients are advised to avoid cigarette smoking and nicotine, as nicotine exacerbates inflammation in Crohn's disease. Patients are often prescribed anti-inflammatories and/or immune suppressors; in some cases, surgery is necessary to remove parts of the colon.