Meckel diverticulum

Meckel diverticulum (also Meckel's diverticulum), is congenital structure of the distal small bowel that occasionally gets inflamed and may present with acute appendicitis-like symptoms.

Meckel diverticulum
Diagnosis in short
LM	small bowel mucosa, +/-gastric mucosa (foveolar epithelium, oxyntic mucosa), +/-pancreatic epithelium
Gross	small bowel outpouching on antemesenteric aspect ~5 cm long, ~60 cm from the ileocecal valve
Site	small intestine
Symptoms	abdominal pain
Prevalence	uncommon ~2% of population
Prognosis	benign
Clin. DDx	acute appendicitis, other causes of abdominal pain
Treatment	surgical removal

General

• Most common congenital anomaly of the gastrointestinal tract.
  • Remnant of the omphalomesenteric duct - a connection of the yolk sac and midgut.

The rule of 2s:

• 2 feet from the terminal ileum
• 2% of the population
• 2% symptomatic.
• 2 inches long.
• 2 year old.
• 2 types of epithelium - gastric and pancreatic.

Main clinical DDx of a symptomatic Meckel diverticulum:

• Appendicitis.

Gross

• Antimesenteric attachement, i.e. a Meckel's diverticulum hangs off the side opposite of the mesentery.

Image

• 

  Meckel diverticulum. (AFIP/WC)

Microscopic

Features:

• Small bowel mucosa.
• +/-Gastric mucosa:
  • Foveolar epithelium: champagne flute-like columnar epithelium.
  • Oxyntic mucosa: parietal cells (pink) and chief cells (purple).
• +/-Pancreatic epithelium:
  • Pancreatic acini.

Images

• Gastric foveolar epithelium in a MD (radiographics.rsna.org).
• Gastric glands in a MD (radiographics.rsna.org).
• Pancreatic glands in a MD (radiographics.rsna.org).

See also

• Small intestine.