4. Crohn’s disease

Staining: HE

Overview. Granulomas are found throughout the thickness of the wall.

Organ: Large intestine

Description:

Many histological findings are important in Crohn’s. Not all of them can be found on this slide:

An aphthous ulcer, which is a knifelike deep ulcer, is present.

Non-caseating granulomas are visible throughout the whole thickness of the wall. These contain giant cells.

Lymphocytes and plasma cells infiltrate the whole thickness of the wall (the whole thickness isn’t pictured here)

Plasma cells, lymphocytes and eosinophils are abundant throughout the whole thickness of the wall.

Cryptal distortion, where the crypts lose their normal round shape and instead take on an irregular shape is present.

Cryptitis, where neutrophils are present in the walls of the crypts, may be present.

Cryptal abscess, where neutrophils are present in the lumen of the crypts, is present.

Paneth cell metaplasia, where Paneth cells are not normally present (the left colon), is present. If Crohn’s affects a part of the colon where Paneth cells are normally present (the right colon), there will be Paneth cell hyperplasia. Paneth cells have large eosinophilic granules that make their cytoplasm look reddish. Look for reddish parts on the bottom of crypts.

Cryptal distortion

Pseudopyloric metaplasia, where the colonic crypts become more like pyloric glands, is probably not present on the slide.

Diagnosis: Crohn’s disease

Risk factors:

  • Western diet
  • Genetic factors

Theory:

Granulomas are only found in 40% of cases, so absence of them is not enough to exclude Crohn’s.

The crypts are distorted because they are repeatedly destroyed and regenerated due to inflammation.

Granulomas
Giant cells
Eosinophils
Neutrophils in the walls of the crypts = cryptitis. This picture is NOT from our slide, it’s from https://librepathology.org/wiki/Cryptitis. I could not find evidence of cryptitis on the slide, however our teacher said that there should be. Maybe you’ll find it.
Neutrophils in the lumen of the crypts = cryptal abscess
Paneth cell metaplasia