GI Pathology - Small Intestine Flashcards
What are 4 causes of intestinal obstruction?
Hernias
Adhesions
Volvulus
Intussusception
What is the most common cause of intestinal obstruction wordwide?
What is the most common cause in the US?
Hernia (3rd most common in the US)
Adhesions
What is the most common cause of intestinal obstruction in children <2 y/o?
Intussusception
What part of the colon is most at risk for volvulus?
Sigmoid colon
What are the clinical signs of intestinal obstruction?
Abdominal pain and distension
Vomiting
Constipation
What age and sex is ischemic bowel disease most common?
What types of disease does it often occur?
An acute obstruction can lead to…
If decreased bowel sounds, guarding or rebound tenderness, what should be done?
F>M; >70 y/o
Co-exists often with cardiac and/or vascular disease
Sudden onset of cramping, LLQ abdominal pain, desire to defecate, bloody diarrhea
Surgery
What are the 2 major etiologies of ischemic bowel disease?
Acute obstruction to flow
- severe atherosclerosis
- AAA
- embolus
Chronic/hypoperfused states
- HF
- shock
- dehydration
- drugs
- vasculitidies
In ischemic disease:
Which infarcts, by themselves, may NOT be fatal?
What is the mortality associated with transmural infarcts?
The worst outcome is associated with occlusion of which artery?
Mucosal and non-transmural infarcts may not be fatal
10% mortality in first 30 days
Superior mesenteric a. occlusion
What is Angiodysplasia?
Where in the GI tract does it occur most commonly?
At what age does it most often present?
A lesion characterized by malformed submucosal and mucosal BVs
Cecum or right colon
After 60 y/o
What are the 3 major variables in the pathogenesis of ischemic bowel disease?
- Severity of vascular compromise
- Duration
- Vessels affected
What is melena vs. hematochezia?
Melena is a dark, sticky stool containing dried blood
Hematochezia is bright red feces
What is the presentation of malabsorption?
What is the hallmark?
What disorders are commonly associated with malabsorption in the US? (4)
Chronic diarrhea, accompanied by gas, abdominal pain, borborygami, anorexia and weight loss
Hallmark is steatorrhea
Pancreatic insufficiency
Celiac disease
Crohn disease
Intestinal graft vs. host disease
Malabsorption results from disturbances in at least one of the following 4 phases:
Intraluminal digestion - protein, carb and fat digestion
Terminal digestion - hydrolysis of carbs and peptides in the brush border
Transepithelial transport - nutrients, fluid and electrolytes are transported across and processed within the intestinal epithelium
Lymphatic transport of absorbed lipids
What is the definition of diarrhea?
What are the definitions of the following types of diarrhea? Secretory diarrhea Osmotic diarrhea Malabsorptive diarrhea Exudative diarrhea
“An increase in stool mass, frequency or fluidity, typically greater than 200 gm/day”
Secretory diarrhea: isotonic stool that persists during fasting
Osmotic diarrhea: occurs in lactase deficiency - due to excessive osmotic forced exerted by unabsorbed luminal solutes (approx >50 mOsm more conc. than plasma)
Malabsorptive diarrhea: from nutrient malabsorption - ceases with fasting
Exudative diarrhea: from inflammatory disease, characterized by purulent, bloody stools that persist during fasting
Celiac disease (adult-variant)
Age of onset
Major symptoms
Females have greater incidence of what symptom?
What feature is common?
30-60 y/o
Chronic diarrhea, bloating
Chronic fatigue, F>M
Malabsorption
Celiac disease (child-variant)
Which gender is at greater risk?
What symptoms are common from 6-24 mo?
What symptoms are common for older children?
What are some extraintestinal symptoms?
M=F
6-24 mo: irritability, abdominal distension, chronic diarrhea, weight loss, muscle loss
Older: abdominal pain, N/V, bloating, constipation
Extraintestinal: arthritis/arthralgia, aphthous ulcers, anemia, delayed puberty, etc.
Almost all patients with Celiac disease carry which 2 alleles?
HLA-DQ2 or HLA-DQ8
What is the recommended test for Celiac disease?
Serum IgA endomysial Abs (EMA) and serum IgA tissue transglutaminase (tTG) Abs
tTG is the single recommended serologic test for Celiac disease screening
What is environmental enteropathy?
What do affected individuals suffer from?
What is the cause?
A disease prevalent in areas/populations with poor sanitation or hygiene, such as developing countries.
Malabsorption, malnutrition, stunted growth and defective intestinal mucosal immune function.
The cause is unknown and there are not any means for diagnosis permitted at this time.
What is autoimmune enteropathy?
What is the inheritance?
In what age is it most common?
Autoantibbodies to which cells are common?
A disorder characterized by severe persistent diarrhea and autoimmune disease.
X-linked
Young children
Enterocytes and goblet cells, sometimes parietal or islet cells.
What is IPEX?
What is the associated germline mutation?
A severe, familial form of autoimmune enteropathy
FOXP3 mutation
What is Abetalipoproteinemia?
What is the inheritance?
What protein is defective?
What stain is used?
What are 3 major symptoms?
What cells are seen on peripheral blood smear?
A rare disorder characterized by inability to secrete triglyceride-rich lipoproteins
AR
Microsomal triglyceride transfer protein (MTP) - pts. cannot assemble or export lipoproteins which leads to intracellular lipid accumulation
Red-O
Failure to thrive, diarrhea and steatorrhea
Acanthocytic red cells (burr cells)
What are the 2 types of lactase deficiency and their features?
Congenital lactase deficiency: mutation in gene encoding lactase.
-rare and presents as exploding diarrhea and abodminal distension upon milk ingestion
Acquired lactase deficiency: down-regulation of lactase gene occurs.
- common in NA, AA and Chinese pops.
- can be acquired post infection and may resolve
- SX include fullness, diarrhea, flatulence, etc.
Of the 4 malabsorptive defects (intraluminal digestion, terminal digestion, transepithelial transport and lymphatic transport), which are associated with the following diseases?
Celiac disease Environmental enteropathy Autoimmune enteropathy Abetalipoproteinemia Lactase deficiency Whipple disease
Celiac disease - terminal digestion and transepithelial transport
Environmental enteropathy - terminal digestion and transepithelial transport
Autoimmune enteropathy - terminal digestion and transepithelial transport
Abetalipoproteinemia - transepithelial transport
Lactase deficiency - terminal digestion
Whipple disease - lymphatic transport/absorption
Vibrio cholera
Pathogenesis
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (2)
Pathogenesis: cholera toxin leads to constant AC activation and increasing cAMP, which leads to massive Cl- secretion and diarrhea.
Reservoir: shellfish Transmission: F-O route, water Affected sites of the GI tract: SI Symptoms: severe watery diarrhea Complications: dehydration and electrolyte imbalances
What is the most common bacterial enteric pathogen in developed countries and is an important cause of traveler’s diarrhea (food poisoning)?
C. jejuni
Campylobacter jejuni
Pathogenesis
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (2)
Pathogenesis: motility, toxin production, adherence and invasion.
Reservoir: chicken, sheep, pig, cattle Transmission: poultry, milk, other foods Affected sites of the GI tract: colon Symptoms: watery or bloody diarrhea Complications: reactive arthritis and Guillan-Barre
Shigella
Pathogenesis
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (4)
Pathogenesis: they are resistant to the acidic environment of the stomach, so only a small amount can cause an infection.
Reservoir: humans
Transmission: F-O route, food, water
Affected sites of the GI tract: left colon, ileum
Symptoms: bloody diarrhea
Complications: reactive arthritis, urethritis, conjunctivitis, HUS
Salmonella
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (2)
Reservoir: poultry, farm animals Transmission: meat, poultry, eggs, milk Affected sites of the GI tract: colon and SI Symptoms: watery or bloody diarrhea Complications: sepsis, abscess
What patient ages are at the greatest risk for Salmonella infection?
What time of the year?
What is required to make a DX?
What patients are at risk for infection? (6)
Very young anf very ol
Summer and fall
Stool cultures required
Cancer Immunosuppressed pts. Alcoholics CVD Sickle cell disease Hemolytic anemia
What is the Typhoid fever (enteric fever) “symptomatic phases”?
What are some extra-intestinal organ system manifestations? (5)
What rash is classic?
First, anorexia, abdominal pain, bloating, N/v and bloody diarrhea, followed by an asymptomatic phase that gives way to bacteremia and flu-like symptoms.
CNS, CVS, pulmonary, Gb, skin
Erythemtaous maculopapular rash (Rose spots)
Gallbladder colonization by S. typhi or S. paratyphi may be associated with…
Gallstones and a chronic carrier state
Yersinia
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (4)
Reservoir: barn animals
Transmission: pork, water, milk
Affected sites of the GI tract: ileum, appendix, right colon
Symptoms: abdominal pain, fever, diarrhea
Complications: reactive arthritis, myocarditis, kidney disease, erythema nodosum
Clinically, what does Yersinia mimic?
What does it mimic morphologically?
What enhances the virulence of Yersinia?
Appendicitis
Crohn disease
Iron
What are the 5 subtypes of an E. coli infection?
Enterotoxigenic (ETEC) - traveler's diarrhea Enteropathogenic (EPEC) Enterohemorrhagic (EHEC) - O157:H7 Enteroinvasive (EIEC) Enteroaggregative (EAEC)
Clostridium difficile
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (2)
What is the histological association?
Reservoir: humans, hospitals Transmission: abx allow emergence Affected sites of the GI tract: colon Symptoms: watery diarrhea, fever Complications: relapse, toxic megacolon
Pseudomembranes, made up of inflammatory cells and debris at the sites of colonic mucosal injury
Whipple disease
Reservoir Transmission Affected sites of the GI tract Symptoms Complications (2)
Reservoir: unknown Transmission: unknown Affected sites of the GI tract: SI Symptoms: malabsorption Complications: arthritis, CNS disease
What is the morphologic hallmark of Whipple disease?
Dense accumulation of distended, foamy macrophages in the small intestinal lamina propria.
What infection causes approx. half of all gastroenteritis outbreaks worldwide?
Norovirus
What is the reservoir for Norovirus?
What are symptoms?
What is the progression of the infection?
Contaminated food and water. Person-to-person transmission underlies most sporadic cases.
N/V, watery diarrhea and abdominal pain
It is self-limited in non-immunocompromised patients
At what age are children most susceptible to Rotavirus?
What is it the most common cause of?
What viral factor is linked to the enterocyte damage from Rotavirus?
What causes the diarrhea?
6-24 mo.
Severe childhood diarrhea and diarrheal mortality worldwide
Non-structural protein 4 (NSP4)
Loss of mature enterocytes, resulting in malabsorption
What patients does Adenovirus most commonly affect?
What does it cause?
Immunocompromised pediatric patients
Diarrhea, vomiting and abdominal pain
What is the pathogenesis of Ascaris lumbricoides?
Clinically, what can the worms and the larvae cause on their own?
Ingested eggs hatch in the intestines and larvae penetrate the intestinal mucosa. The larvae then migrate to systemic circulation and enter lungs to grow in the alveoli. 3 wks later the larvae are coughed up and the process restarts.
Worms: Eosinophil-rich inflammatory reaction that causes obstruction of the intestine and biliary tree
Larvae: can form hepatic abscesses and cause Ascaric pneumonitis
What is a feature of a Strongyloides infection that is unique compared to other parasitic intestinal infections?
Their eggs can hatch within the intestine and release larvae that penetrate the mucosa and cause an autoinfection. This means that a STrongyloides infection can last for life in immunosuppressed pts.
What is the reservoir for Strongyloides larvae?
What can a Strongyloides infection incite?
Fecally contaminated ground soil and penetrate unbroken skin.
May incite a strong tissue reaction and induce peripheral eosinophilia.
What does an infection of Enterobius vermicularis (pinworms) cause?
What is the route of transmission?
They live within the lumen so they rarely cause a serious illness, but they lay their eggs in the perirectal mucosa, which causes significant rectal and perianal pruritis.
F-O route
How are intestinal cestodes transmitted?
Where do they reside in the GI tract?
What are some symptoms?
By ingestion of undercooked meats.
Within the lumen only.
Most cases are asymptomatic, but there may be abdominal pain, diarrhea and nausea.
Entamoeba histolytica is common in which countries?
What does the infection cause?
What are some symptoms?
India, Mexico and Colombia
Cysts/abscesses in the GI tract, liver, brain and kidneys
Abdominal pain, bloody diarrhea or weight loss
What are symptoms of a Giardia infection?
What 2 responses are important to help clear it?
Chronic diarrhea, malabsorption (greasy stools) and weight loss
Secretory IgA and IL-6
Cryptosporidium is a major cause of diarrhea in which patients?
How is it diagnosed?
AIDS/immunocompromised. In healthy patients, it is a self-limiting infection.
Oocytes in then stool
What histological feature is classic of Celiac disease?
What is an extra-intestinal manifestation?
Loss of villi
Dermatitis herpetiformis - itchy, blistery skin rash w/ granular IgA deposits
