Flashcards in GI 2 Deck (68):
What is the general cause of ischemic bowel disease?
Decreased intestinal blood flow
What is the most common type of ischemic bowel disease?
Acute intestinal ischemia
In acute intestinal ischemia, injuries can range from mucosal _______ to transmural bowel ________.
range from mucosal necrosis to transmural bowel infarction.
Ischemic bowel disease may occur if there is occlusion of one of three major vessels, where extensive ______ may occur unless the rich vascular anastomoses prevent ischemia.
infarction may occur unless collateral flow prevents it.
Which specific artery is most often occluded in the case of acute intestinal ischemia?
The superior mesenteric artery.
What are the three levels of severity of ischemic bowel disease? Which levels correspond to chronic occlusion and which levels correspond to acute artery occlusion?
1. Mucosal infarction
2. Mural infarction
3. Transmural infarction
Mucosal and mural are due to chronic OR acute hypoperfusion. Transmural is a result of acute occlusion of a major mesenteric artery.
Name six conditions that are predisposing for acute intestinal ischemia.
2. Aortic aneurysm
3. Hypercoagulable state
4. Oral contraceptive use
5. Embolization of cardiac vegetation (crap on valves)
6. Aortic atheroma (plaque)
Are cardiac failure, shock, dehydration, drugs that vasoconstrict, systemic vasculitides, portal hypertension, and mass effect from tumors examples of other conditions associated with bowel ischemia?
In ischemic bowel disease, the infarcted bowel is _______ and diffusely purple. Hemorrhage is seen in the submucosa, especially in ________ occlusions. Ischemic injury begins in the _______ and spreads ________. Within 18 to 24 hours there is a thin, fibrinous ________ over the serosa. The mucosal surface will show irregular white sloughs and the wall becomes thin and _______, and bubbles of gas may be present in the bowel wall and mesenteric veins.
infarcted bowel is edematous and diffusely purple.
hemorrhage seen in venous occlusions especially.
Ischemic injury begins in the mucosa and spreads outwards.
18-24 hours there is a thin, fibrinous exudate over the serosa.
Mucosal surface will show irregular white sloughs and the wall becomes thin and distended.
Name two complications from ischemic bowel disease.
1. Bacterial produce gangrene within 24 hours and can perforate the bowel.
2. Healing with granulation tissue and fibrosis with eventual stricture formation (narrowing) .
What is adynamic ileus?
When the bowel proximal to an infarcted area becomes clogged due to abnormal smooth muscle and peristalsis function.
What is celiac disease?
An autoimmune response to the ingestion of gluten that results in atrophy of the intestinal villi.
Celiac disease is characterized by generalized __________ and mucosal lesions.
What if someone has a positive response to taking gluten-containing foods out of their diet?
Then they probably have Celiac disease.
90% of patients with Celiac disease carry HLA____, HLA___, and _____.
HLA B8, HLA DR8, and DQ2
What specific protein in gluten is suspected of causing Celiac disease? What is the mechanism?
Gliadin interacts with the immune system, leading to the killing of enterocytes and damaging the mucosal epithelium --> loss of tight junctions and leaky intestines.
Name the cells that one would find in a section of bowel from a person with Celiac disease.
Increased CD8+ T cells.
Increased plasma cells, mast cells, eosinophils in the lamina propria but NOT in deeper layers.
Pseudomembranous colitis is an example of ________ enterocolitis in which the organism _________ proliferates following antibiotic use, releasing toxins in to the GI tract.
example of infectious enterocolitis in which C. difficile releases toxins into the GI tract.
Morphological changes of pseudomembranous colitis include the adhesion of a _________ mucus to the superficial mucosa, denuded surface epithelium and a dense infiltrate of _________ in the lamina propria. Superficially damaged crypts with released exudate resembles a ________.
fibrinosupprative mucus and infiltration of neutrophils in the lamina propria. Damaged crypts with released exudate looks like a volcano.
A herniation of the mucosa and submucosa through the muscular layers of the colon.
What type of factors are primarily responsible for causing diverticulosis? How was this figured out?
Environmental. We know this because the prevalence of the disease in different places is highly variable.
____% of people in western countries are affected by diverticulosis, and the prevalence of the disease _______ (increases or decreases) with age.
10%, prevalence increases with age
Describe a histologic cross section of a colon with diverticulosis in terms of how the layers are affected.
The mucosa, muscularis mucosae, and submucosa layers herneate through the muscularis externa layer.
Which section of the colon is affected by diverticulosis 90% of the time?
Sigmoid colon (distal)
Name the disease: A flask-like 1 cm out-pouching that extends through the muscularis externa and is retained by a serosal connective tissue.
What symptoms are typical of diverticulosis?
Trick question! It is usually asymptomatic.
Name the disease: Chronic, segmental, transmural inflammation of usually the distal small intestine (although can happen anywhere in the GI tract - particularly the right colon).
Which populations are predominantly affected by Crohn's disease?
Adolescents, young adults. Mostly Europeans. Especially high frequency amongst the Jewish pop. Slight female predominance.
Name four factors that are thought to predispose people to Crohn's disease.
1. Genetic: Family Hx of IBD, mutation of NOD2/CARD15 gene.
2. Immunologic: Chronic inflammation, messed up mucosal immune response, immunosuppression therapy.
3. Epithelial defects: Defective transport across epithelium.
4. Microbial: Not understood.
Which GI disease affects ALL layers of the GI tract wall (transmural inflammation)?
Describe five morphological characteristics of Crohn's disease.
1. Trasmural inflammation affecting all layers.
2. Segmental involvement along the length of the tract.
3. Noncaseating granulomas (40-60% of cases).
4. Fissuring with formation of fistulae (abnormal connections made between the fissures or adjacent intestines).
5. Cryptic abscesses! (Also in UC)
Microscopic changes from Crohn's disease include:
1. Infiltration of _________ into the epithelial layer and accumulation within crypts to form crypt ________.
2. Ulceration - the usual outcome.
3. Chronic mucosal change (atrophy, metaplasia).
4. Trasmural, nodular, lymphoid aggregates.
6. Lymphoid aggretates at the interface between mucosa and submucosa.
infiltration of neutrophils; formation of crypt abscesses
Name six clinical manifestations of Crohn's disease.
1. Abdominal pain and diarrhea in 75% of patients.
2. Fever in 50% of pts.
3. Complications include intestinal obstruction and fistulas.
5. Colonic bleeding.
6. Increased risk for small bowel cancer (3X higher) and colorectal cancer.
Name the disease: Narrowing of the GI lumen with bowel wall thickening, serosal extension of mesenteric fat ("creeping fat"), ulceration of the mucosal surface and swelling give a "cobblestone" appearance.
What is ulcerative colitis?
Chronic SUPERFICIAL inflammation (not transmural!) of the colon and rectum.
What causes ulcerative colitis?
Unknown, probably same factors as Crohn's are involved.
Name the disease: Diarrhea and rectal bleeding (risk of moderate anemia) with intermittent attacks. Severe colitis occurs with 20 bloody bowel movements daily with massive hemorrhage being life threatening. Toxic megacolon – extreme dilation of colon and risk of perforation (dangerous complication).
Name three pathologic features that help differentiate ulcerative colitis from other inflammatory diseases.
1. Affects from the distal part of the rectum to a variable distance proximally. Rarely spares the rectum or right (ascending) colon.
2. Inflammation is LIMITED to the colon and rectum (rarely involved the small intestine, stomach, or esophagus).
3. Affects the mucosal surface only. Cases that affect deeper layers are severe and usually asociated with toxic megacolon.
What are the three stages of ulcerative colitis?
Early, progressive, advanced.
Describe eight morphological changes seen in early ulcerative colitis.
1. Raw, red, and granular mucosal surface.
2. Yellowish exudate.
3. Bleeds easily.
4. Superficial erosions or ulcers.
5. Mucosal congestion, edema, and microscopic hemorrhages.
6. Inflammatory infiltrate in the lamina propria.
7. Damage of colorectal crypts and infiltrating neutrophils.
8. Supperative necrosis of crypts --> crypt abscesses filled with neutrophils.
Describe three morphological changes seen in progressive ulcerative colitis.
1. Mucosal folds are lost.
2. Crypt abscesses coalesce laterally (crypt distortion) and form pseudopolyps.
3. Granulation tissue develops without strictures (stenoses).
Describe three morphological changes seen in advanced ulcerative colitis.
1. Large bowel is shortened, especially on the left (descending) side.
2. Mucosal folds are lost and replaced by granular or smooth mucosal pattern.
3. Atrophy of mucosa with chronic inflammatory infiltrate in the mucosa and upper submucosa.
Are most symptoms from ulcerative colitis intermittent with remission in between attacks?
Can a person with moderate colitis have recurrent episodes of loose, bloody stools, cramps, low-grade fever lasting days to weeks, and moderate anemia from blood loss?
What is toxic megacolon? What inflammatory disease is it associated with?
It is a complication of Ulcerative collitis. It is characterized by extreme dilation of the colon and an increased risk of perforation.
People with long-standing ulcerative colitis have a higher risk of ______ cancer than the general population.
Describe a severe case of ulcerative colitis.
>20 bloody bowel movements/day resulting in dehydration and anemia. Can be life-threatening.
Non-neoplastic polyps usually occur sporadically, particularly in the ______, and they _______ in frequency with age.
occur in colon, increase in frequency with age
What percentage of epithelial polyps in the large intestine are non-neoplastic? What percentage of people over 60 have them?
90% of all epithelial polyps are non-neoplastic. 50% of people over 60 have them.
Most polyps are _______, small (<5mm dia), nipple-like, hemispherical, smooth protrusions of the mucosa.
Over half of non-neoplastic polyps are found in the _________ colon.
Do non-neoplastic polyps have malignant potential? What is the exception.
Generally, no. Exception is that some hyperplastic polyps - sessile serrated adenomas located on right side of the colon may be the precursor to colorectal carcinomas.
Which type of polyps are considered premalignant that arise from the mucosa?
____% of adenomatous polyps of the colon in the US are found in the rectosigmoid region.
How are adenomatous polyps classified?
Tubular, villous, tubulovillous
Describe a tubular adenomatous polyp.
They have a head and a stalk. The stalk is covered by normal epithelia and the head is composed of neoplastic epithelium with varying degrees of dysplasia.
Describe a villous adenomatous polyp.
Large (>2 cm), broad and elevated lesion with a shaggy, cauliflower-like surface with variable degrees of dysplasia and foci of carcinomas.
Describe a tubulovillous adenomatous polyp.
Have features of tubular and villous.
Which adenomatous polyp type is more likely to have foci or carcinomas and therefore carry a higher cancer risk?
Name five risk factors for colorectal cancer.
2. Chronic IBD
3. Prior colorectal cancer
5. Genetics/family Hx
Name the two pathways involved in the development of colorectal cancer.
APC/beta-catenin and mismatch repair (microsatellite instability) pathways.
Name three clinical manifestations of colorectal cancer. How do they metastasize?
1. Occult blood in the stool (most common).
2. Iron deficiency anemia.
Metastasis through direct extension or vascular/lymphatic invasion (particularly for liver).
The vast majority of colorectal cancers are _________.
What is appendicitis?
Inflammatory disease of the wall of the vermiform appendix that leads to transmural inflammation and perforation with peritonitis (if untreated).
What inflammatory cell type is involved in infiltrating the wall of the appendix in a case of appendicitis?
What cell type can be seen infiltrating the intestinal epithelia in a case of Celiac disease? What do these cells end up doing?
Intra-epithelial T lymphocytes end up killing the intestinal epithelium.
What is a pseudopolyp and which disease is it often found in?
When much of the mucosal surface is eroded, leaving the few, undamaged areas look like they are polyps sticking out. Seen in ulcerative colitis.