An introduction to gastrointestinal pathology

Gastrointestinal pathology is a large part of pathology as radiologists can often describe the extent of disease... but don't get the diagnosis right all the time.

Normal

Layers of the alimentary canal:

• mucosa (epithelium, lamina propria, muscularis mucosa)
• submuscosa and submucosal plexus (or Meissner's plexus)
• muscularis externa (inner longitudinal, myenteric plexus (or Auerbach's plexus) outer circumferential)
• adventitia (if retroperitoneal), serosa (if intraperitoneal)

Bowel

Small bowel

• Villi - should see three good ones in a normal biopsy.
• Crypts.
• Paneth cells.

Duodenum

• Small bowel (as above).
• Submucosal glands (Brunner's glands).

Large bowel vs. small bowel

• Small intestine.
  • Villi (key feature).
  • Brunner's glands - duodenum only (key feature).
  • Paneth cells more common.
    • Paneth cells are in the base of the crypts and have eosinophilic granules. They are found (normally) in the small bowel and right colon. They may appear on the left side (i.e. descending colon) in pathologic states, e.g. IBD.
• Large intestine
  • More goblet cells.
  • More lymphocytes usually.

Intestinal polyps

Main article: intestinal polyps

The bread and butter of gastrointestinal pathology.

Esophagus

Main article: Esophagus

Largely forgotten organ at SB... but no shortage of these at SMH.

Stomach

Main article: Stomach

H. pylori, cancer and more...

Small bowel

Main article: Small bowel

The part of the GI tract pathology mostly forgot.

Duodenum

Main article: Duodenum

Commonly biopsied.

Gallbladder

Main article: Gallbladder

A growth industry... with the expanding waist lines in the (Western) world.

Liver

Main article: Liver

An organ that pathologists now sometimes forget.

Colon

Main article: Colon

Includes discussion of the rectum.

Appendix

Main article: Appendix

Acute appendicitis and more...

See also

• Introduction