Diseases of Lower GI - Pathology (not done)

Question 1

Define Gluten Sensitive Enteropathy. Describe the diagnostic histologic features

Answer 1

a

Question 2

Describe the etiology of Whipple’s disease

Answer 2

a

Question 3

Describe the clinical presentation of Whipple’s disease

Answer 3

a

Question 4

List the major causes of diarrheal illness

Answer 4

a

Question 5

Describe acute ischemic colitis

Answer 5

a

Question 6

Describe the complications of acute ischemic colitis

Answer 6

a

Question 7

Describe chronic ischemic colitis

Answer 7

a

Question 8

Describe the complications of chronic ischemic colitis

Answer 8

a

Question 9

Define pseudomembranous colitis. What is its etiology?

Answer 9

Cause: C. Diff

• Often occurs after a course of antibiotics (probably the reason why some people call it “antibiotic associated colitis”)
• Usually due to 3rd generation cephalosporins
• Common in hospitalized pts (up to 30%)

Presentation: fever, leukocytosis, abdominal pain, cramps, watery diarrhea

Pathogenesis:

• Antibiotics cause disruption of colonic flora => C. diff overgrowth
• C Diff releases toxins => disruption of epithelial cytoskeleton, tight junction barrier loss, cytokine release and apoptosis

Question 10

Describe the pseudomembrane of pseudomembranous colitis

Answer 10

• Adherent layer of inflammatory cells — “Volcano like” eruption of PMNs
• Mucinous debris at sites of of colonic mucosal injury
• Crypt loss

It seriously looks like a thick green/tan film or plaque over the erythematous colon

Question 11

a

Answer 11

a

Question 12

Describe the two histologic patterns associated with the clinical entity of microscopic colitis

Answer 12

Collagenous colitis

• Thickened subepithelial collagen layer
• Lymphocytes still expanding the lamina propia
• Normal crypts

Lymphocytic colitis

• Increased intraepithelial lymphocytes
• Normal crypts

Question 13

Explain why the disease is called “microscopic” colitis

Answer 13

You can’t see this grossly on a colonoscopy! That’s why GI docs still do a biopsy and sent it to pathology b/c it can only be diagnosed microscopically.

Question 14

What are the gross and microscopic features of Crohn disease?

Answer 14

• Skip lesions
• Ileal involvement (“regional enteritis”) — can be “mouth to anus”!
• Fissuring ulcers, sinus tracts, fistula
• Transmural chronic inflammation
• Inflammatory strictures
• Thickened wall!
• Granulomas (1/3 of cases)

Question 15

What are the gross and microscopic features of UC?

Answer 15

• ALWAYS rectal involvement w/ retrograde continuous diffuse disease
• No ileal involvement
• Disease is worse distally
• Mucosal inflammation only (not transmural)
• No fissures, sinuses, or fistula tracts
• Thinned wall!

Question 16

Describe the anatomic process underlying diverticulosis

Answer 16

Over a lifetime, decreased dietary fiber => Decreased stool bulk => Elevated intraluminal pressure => Mucosal herniation through focal defects in the bowel

• Most common in sigmoid colon
• Asymptomatic or intermittent cramping, lower abdominal discomfort

Question 17

List the clinical factors that predispose people to diverticulosis

Answer 17

Not enough fiber in your diet

Doesn’t say much more than that

Question 18

What is a diverticulum?

Answer 18

An outpouching or herniation of the mucosa and submucosa

Question 19

Describe the histologic features of appendicitis

Answer 19

• Mucosal ulceration
• Transmural acute and chronic inflammation
• Extension of inflammation into the mesoappendix

Question 20

How are Crohn disease and UC similar?

Answer 20

Epidemiology

• F>M
• Most common in white people (2-9x higher in Ashkenazi Jews)

Pathogenesis - generally

• Abnormal host interactions w/ intestinal microbiota
• Causes intestinal epithelial dysfunction
• Ultimately => aberrant mucosal immune responses
• Architectural disorganization