GI Pathology III: Small Intestine Flashcards
What are the clinical features and histological findings in Hirschsprung disease?
Constipation with lack of ganglion cells on histology
What is the infectious agent in pseudomembranous colitis?
C. difficile
What is the common parasitic infection that presents with bloody diarrhea?
E. histolytica
What is the gene mutation in familial adenomatous polyposis (FAP)?
Autosomal dominant mutation of the APC gene
Plicae Circularis
Plicae circularis are folds of the mucosa and submucosa
Paneth Cells
Function in cell defense in the intestine. Paneth cells have lysozymes and defensins.
What are features specific to the duodenum?
Brunner’s Glands
What are features specific to the ileum?
Peter’s Patches
What is the main function of the large intestine?
Absorption of water
Where is Meissner Plexus located?
In the submucosa
Where is Auerbach’s Plexus located?
Between the circular and longitudinal muscle in the muscularis propria
Intussusception
Telescoping of bowel segment into distal segment often at the ileocecal junction
Volvulus
Twisting of the bowel around its mesentery leading to obstruction and can compromise blood flow
Where does volvulus occur in children? Adults?
Children - midgut
Adults - sigmoid
Necrotizing Entercolitis
Most common GI emergency in premature neonates with acute necrotizing inflammation of the small and large bowels
Meckel’s Diverticulum
Disease of 2’s
- 2:1 male to female
- 2 major complications are pain with inflammation and hemorrhage with ulcer
Who is most affected by Hirschsprung disease?
Males in a 4:1 ratio
What is Hirschsprung disease associated with?
Down syndrome
What can pancreatic insufficiency be caused by and what does it result in the malabsorption of?
- Pancreatitis/Cancer
It will affect the absorption of fat and vitamins A, D, E and K
What is the most common type of disaccharide deficiency and what are the symptoms?
Lactase. Osmotic diarrhea.
Abetalipoproteinemia
Decreased synthesis of apolipoprotein B which decreases the amount of chylomicrons leading to the accumulation of fat and cholesterol in the enterocytes - presents as failure to thrive
Celiac Disease
Autoimmune disorder that results in the damage of small intestinal lining when gluten is eaten
Who is celiac disease seen most often in?
Caucasians and Europeans
What is the pathogenesis of celiac disease?
Gluten is converted to gliadin which is deaminated by TTG and is presented to a T cell. The T cell will attack the enterocytes and activate B-cells leading to Ab formation
What happens to the villi in celiac disease?
They are lost from the inflammation
What are the prominent cells seen in celiac disease?
CD8+ T cells
What are the important tests for celiac disease?
- Serologic test for TTG and gliadin Ab
- Biopsy showing villous atrophy
What are some bacterial causes of enterocolitis?
- Cholera
- Campylobacter
- Yersinia
- E. coli
- Shigella
- Salmonella
What are some viral causes of enterocolitis?
- Norovirus
- Rotavirus
What are some of the parasitic causes of enterocolitis?
- Nematodes
- Flatworms
- Protozoans (Giardia, E. histolytica)
What is the histological characteristic of E. histolytica infection?
Flask shaped ulcer
What is the histological finding in pseudomembranous enterocolitis?
Mushroom pseudomembrane
Who is generally affected by collagenous enterocolitis?
Middle to older age women
What is the histological finding of collagenous enterocolitis?
Presence of collagen (blue with trichrome stain)
What is lymphocytic enterocolitis associated with?
Autoimmune diseases
What will be seen on histology of lymphocytic enterocolitis?
Lymphocytes
Whipple Disease
Rare and found in men more commonly. It is caused by Tropheryma whippleli and is engulfed by macrophages where they fill the lamina propria and distend it.
Crohn’s Disease
It is a disordered response to bacteria. Usually affects the terminal ileum but can affect any part of the GI tract and it will show with strictures and serosal creeping fat.
What is seen on histology of Crohn’s disease?
- Transmural inflammation - full thickness of the wall
- Ulceration and non-caseating granulomas
Ulcerative Colitis
Autoimmune with relapsing attacks of bloody mucoid diarrhea with pain with diffuse continuous inflammation
What layers does ulcerative colitis affect?
Only the mucosa and submucosa, and there are NO non-caseating granulomas
What is the diarrhea of Crohn’s like?
Non-bloody
What is the diarrhea of ulcerative colitis like?
Bloody
What is a distinguishing feature in the how the intestines are affected in Crohn’s VS ulcerative colitis?
Crohn’s will have skip areas and thus is focal.
UC is continuous and therefore diffuse.
