B53 Inflammatory bowel diseases

Question 1

What is the basic eitiology of Inflammatory bowel disease? 3 major factors/processes that cause it.

Answer 1

Genetic susceptibilty: higher incidence in relatives, and associated with specific MHC2 alleles. Crohns disease is associated with certain NOD2 mutations.

Failure of immune regulation: Innapropriate immune response against the normal flora of the gut and also self antigens.

Involvment of the GI flora: It is highly prevalent in western countries and extremely rare in the developing world. Hygeine hypothesis of insufficient childhood exposure to innocuous microbes, exposure as an adult results in innapropriate immune resp. Hyperactive Th response and less active cellular response.

Question 2

Crohn disease, bullet points

Answer 2

• Forms anywhere in the intestines, mostly in the terminal ileum.
• Non-continuous, spares areas called skip lesions
• Inflammation through all layers of the bowel
• Causes thick edematous segments of bowel, fibrosis and stenosis
• Causes deep knife-like ulcers, which may form fistulas between loops of intestine, bladder, vagina, abdominal or anal skin.
• Ulcerations form long, deep, sigmoid lesions, with edematous, inflamed areas in between, forming the gross morphology cobblestone mucosa.
• Strong lymphoid infiltration lots of T helper cells, specifically Th17 cells.
• Appears in the teens and twenties.
• Mild female preference
• Non-caseating granulomas form in about 1/3rd of the cases.
• Causes malabsorption syndrome (is in the ileum and jejunum, the absorptive parts)
• Increases risk of malignancy if it is in the colon.
• Remitting relapsing with years on and years off. Progressive shortening of the intestine due to resection.
• ~50% will have re-occurence within 10 years after surgery, even if the there is a wide margin of resection around the afflicted region, occuring at the site of the surgical anastomosis.

Question 3

Ulcerative colitis, bullet points

Answer 3

• Limited to the colon
• Always begins at the rectum and progresses backwards
• Progresses continuously and there are no skip lesions
• Only the mucosa and submucosa is inflamed.
• Bowel becomes thin, not thick, and strictures are rare
• Pseudopolyps form when areas of mucosa regenerate, and the surrounding area is atrophied, thus they protrude from the surrounding area.
• Ulcers are broad-based and shallow.
• Even though the inflammation is limited to the mucosa and submucosa, ulcerative colitis can damage and impair the enteric nervous system of the muscular layer, and cause colon paralysis, and behind it toxic megacolon.
• Has a high malignant potential and should be biopsied to check for colon cancer, if significant dysplasia, prophylactic resection.
• Slight female preference
• Resection of the affected colon will cure the intestinal disease, but extraintestinal symptoms will still relapse
• Smoking decreases risk for Ulcerative colitis.
• Extra-intestinal symptoms:
  
  • ​Migratory polyarthritis

Question 4

What is the clinical presentation for Ulcerative Colitis?

Answer 4

Remitting relapsing periods of bloody diarrhea, with stringy mucoid material in it.

Abdominal pain and cramps. Lasts from days to months.

Question 5

What is the clinical presentation of Crohn’s disease?

Answer 5

First, it is highly variable.

• Most patients: mild diarrhea, fever, and abdominal pain
• 20% of patients present with symptoms mimicing appendicitis or bowel perforation and strong lower right quadrant abdominal pain.
• Some present with bloody diarrhea.

May also present with:

• Iron deficient anemia
• malabsorption syndrome and vitamin or lipid malabsorption syndromes.
• Stricture and obstructive ileus.

Question 6

What are the extraintestinal symptoms of IBD?

Answer 6

Extra-intestinal symptoms:

• Migratory polyarthritis
• Ankylosing spondylitis - inflammation and eventual fusion of the joins between the lumbar vertebrae.
• Erythema nodosum
• Bile duct inflammatory disorders, pericholangitis, primary sclerosing cholangitis
• and bile obstruction, stone formation
• Uveitis - choroid, iris, and ciliary body inflamation of the eye
• Sacroilitis - sacroiliac joint inflammation.
• Finger clubbing occurs in Crohn’s and not UC, but bile duct involvement is more frequent in UC than Crohns.

Question 7

What cancers are associated with IBD?

Answer 7

8-10 years following the diagnosis of IBD, the risk of cancer sharply increases.

Patients should be enrolled in monitoring programs to regularly screen for colon cancer.

Patients with primary sclerosing cholangitis have an immediately higher risk of cancer, and should be regularly screened as soon as it is diagnosed.

This screening is extensive, not just endoscopy, but also regular mucosal biopsies from multiple sites.