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What is the pathogenesis of intussusception?
A segment of the intestine telescopes into the distal segment, leading to obstruction and potentially infarction due to mesenteric vessel compression.
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What are the morphological features of intussusception?
Involves an invaginated segment of the intestine, compressing its mesentery.
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What is the etiology of intussusception in children?
Usually no underlying anatomical defect; may be associated with viral infections and rotavirus vaccines.
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What is the epidemiology of intussusception?
Most common cause of intestinal obstruction in children under 2 years.
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What is the pathogenesis of Hirschsprung Disease?
Congenital defect in colonic innervation due to disruption of neural crest cell migration.
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What is the morphology of Hirschsprung Disease?
Aganglionic region may appear normal or contracted; proximal colon undergoes progressive dilation.
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How is Hirschsprung Disease diagnosed microscopically?
By histological confirmation of the absence of ganglion cells in the affected segment.
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What is the etiology of Hirschsprung Disease?
Congenital defect involving neural crest cell migration; associated with genetic mutations and trisomy 21.
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What is the epidemiology of Hirschsprung Disease?
Occurs in approximately 1 in 5000 live births; more common in males.
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What is the pathogenesis of abdominal hernia?
Weakness in the peritoneal cavity wall allows protrusion of a serosa-lined pouch, leading to potential incarceration and strangulation.
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What is the morphology of an abdominal hernia?
A serosa-lined pouch protruding through a defect in the peritoneal cavity wall.
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What is the etiology of abdominal hernias?
Commonly occur through inguinal and femoral canals, umbilicus, or surgical scars.
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What are the two major mechanical causes of intestinal obstruction?
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What is the pathogenesis of Ischemic Bowel Disease?
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What are the vulnerable areas in Ischemic Bowel Disease?
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What is the morphology of Ischemic Bowel Disease?
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What characterizes acute ischemia microscopically?
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What leads to sigmoid diverticulitis?
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What is the morphology of diverticula in the sigmoid colon?
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What are diverticula?
Pouches (0.5-1 cm) in the sigmoid colon with a thin wall.
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What is the microscopic appearance of diverticula?
Protrusion of mucosa and submucosa through muscularis propria.
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What are the causes of diverticula?
Elevated intraluminal pressure, Western diet, sedentary lifestyle.
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What is the epidemiology of diverticula?
Rare under 30; 50% prevalence in adults over 60 in Western populations.
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What causes Cystic Fibrosis?
Mutations of the CFTR gene affecting ion transport.
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What is the pathogenesis of Cystic Fibrosis?
Leads to inadequate luminal hydration and exocrine pancreatic insufficiency.
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What is the microscopic appearance in Cystic Fibrosis?
Duct obstruction and tissue damage in the pancreas.
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What triggers Celiac Disease?
Ingestion of gluten in genetically predisposed individuals.
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What are the morphological features of Celiac Disease?
Crypt hyperplasia, villous atrophy, increased intraepithelial lymphocytes.
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What is the epidemiology of Celiac Disease?
Worldwide prevalence of about 1%; manifests in childhood and adulthood.
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What is the onset age for Celiac Disease in children?
Between 6 and 24 months after gluten introduction.
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What is the common age range for Celiac Disease onset in adults?
Between 30 and 60 years of age.
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What is Environmental Enteric Dysfunction?
A syndrome of impaired intestinal function.
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What causes malabsorption in Environmental Enteric Dysfunction?
Small intestinal colonization by toxigenic coliform bacteria.
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What does a small intestinal biopsy show in Environmental Enteric Dysfunction?
Blunted villi and chronic inflammation.
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What is a common microscopic finding in Environmental Enteric Dysfunction?
Similar to celiac disease: blunted villi and chronic inflammation.
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Where is Environmental Enteric Dysfunction most prevalent?
Sub-Saharan Africa, northern Australia, southern India, and poor areas in South America and Asia.
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What is Lactase Deficiency?
Inability to digest lactose due to insufficient lactase enzyme.
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What causes osmotic diarrhea in Lactase Deficiency?
Unabsorbed lactose exerts an osmotic force in the intestinal lumen.
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What is Congenital lactase deficiency?
A rare autosomal recessive disorder caused by mutations in the lactase gene.
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What is the prevalence of acquired lactase deficiency?
Affects roughly two-thirds of the world’s population.
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What is Abetalipoproteinemia?
A rare autosomal recessive disease marked by inability to secrete triglyceride-rich chylomicrons.
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What is a characteristic finding in peripheral blood smears in Abetalipoproteinemia?
Presence of acanthocytic red cells (spur cells).
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What are the two types of Microscopic Colitis?
Collagenous colitis and lymphocytic colitis.
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What characterizes collagenous colitis?
Presence of a dense subepithelial collagen layer.
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What is a symptom of both types of Microscopic Colitis?
Chronic, nonbloody, watery diarrhea without weight loss.
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What is the histological difference between collagenous colitis and lymphocytic colitis?
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What is the morphology of collagenous colitis?
Typically normal radiologic and endoscopic studies.
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What are the microscopic features of collagenous colitis?
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What is the etiology of lymphocytic colitis?
Idiopathic, associated with celiac disease and autoimmune diseases.
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Who is primarily affected by collagenous colitis?
Middle-aged and older women.
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What is the pathogenesis of graft-versus-host disease?
Donor T cell-mediated damage to recipient’s epithelial cells after transplantation.
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What is a common microscopic finding in graft-versus-host disease?
Epithelial apoptosis, especially of crypt cells.
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What are the causes of infectious enterocolitis?
Bacteria, viruses, and parasites.
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What are some bacterial causes of infectious enterocolitis?
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What is the global impact of infectious enterocolitis?
More than 1 million deaths annually, >10% in children under 5.
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What is the pathogenesis of cholera?
Vibrio cholerae produces cholera toxin, increasing cAMP and chloride ion outflow into the gut lumen.
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What activates the cystic fibrosis transmembrane conductance regulator (CFTR)?
Increased cAMP binds and activates CFTR.
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What is the result of CFTR activation?
Massive outflow of chloride ions into the gut lumen.
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What does the outflow of chloride ions cause?
Creates an osmotic gradient, leading to massive secretory diarrhea.
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What is the morphology of mucosal biopsy specimens in cholera?
Show only minimal morphologic alterations.
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What bacteria causes cholera?
Caused by Vibrio cholerae.
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How is cholera primarily transmitted?
Through contaminated drinking water.
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What is a common symptom of severe cholera?
Rapid dehydration, shock, and potential death.
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What causes Campylobacter Enterocolitis?
Caused by Campylobacter jejuni.
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What are the virulence factors of Campylobacter jejuni?
Includes motility, adherence, toxin production, and invasion.
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What is the microscopic appearance of Campylobacter Enterocolitis?
Characterized by prominent lamina propria and intraepithelial neutrophil infiltrates.
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What is a common source of Campylobacter infections?
Associated with ingestion of raw or undercooked meat.
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What is a major epidemiological fact about Campylobacter?
A common cause of acute diarrhea worldwide.
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What is the pathogenesis of Shigellosis?
Shigella organisms resist stomach acid and infect epithelial cells.
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What does Shiga toxin do?
Inhibits eukaryotic protein synthesis and causes host cell death.
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What is the morphology of Shigellosis?
Infections are most prominent in the rectosigmoid colon.
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What is the etiology of Shigellosis?
Caused by Shigella (gram-negative, nonmotile bacteria).
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How is Shigellosis transmitted?
Highly transmissible via the fecal-oral route.
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What is a significant burden of Shigellosis?
A common cause of bloody diarrhea (dysentery).
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What are the annual global cases of E. coli infections?
Approximately 170 million cases
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What is the annual death toll from E. coli infections?
About 160,000 deaths
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What syndrome can be caused by EHEC?
Hemolytic uremic syndrome
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What toxin does ETEC produce?
Heat-labile toxin and heat-stable toxin
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What does EPEC cause in the intestines?
Local loss (effacement) of microvilli
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What type of diarrhea does EHEC cause?
Can cause dysentery
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What characterizes EIEC infection?
Invasion of gut epithelial cells
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How does EAEC cause symptoms?
By producing heat-labile and Shiga-like toxins
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What is a principal cause of traveler’s diarrhea?
ETEC
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What is the main cause of nontyphoid salmonellosis?
Salmonella enteritidis
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What is a common symptom of Salmonellosis?
Diarrhea, nausea, vomiting, fever
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How is nontyphoid Salmonella typically transmitted?
Through contaminated food
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What is the annual incidence of Salmonellosis in the U.S.?
Over 1 million cases
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What causes Typhoid fever?
Salmonella typhi and Salmonella paratyphi
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What happens to Peyer patches in Typhoid fever?
They enlarge into plateau-like elevations
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What type of ulcers are formed in the ileum due to Typhoid fever?
Oval ulcers oriented along the long axis
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What are the causes of typhoid fever?
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What are the morphological features of typhoid fever?
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What is the microscopic appearance in typhoid fever?
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What is the epidemiology of typhoid fever?
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What is the pathogenesis of pseudomembranous colitis?
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What are the morphological features of pseudomembranous colitis?
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What is the microscopic appearance of pseudomembranous colitis?
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What causes mycobacterial infections in the GI tract?
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What is the morphology of mycobacterial infections?
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What is the microscopic appearance in mycobacterial infections?
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What are the causes of granulomas with caseous necrosis?
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What is the common presentation of M. avium in immunocompromised patients?
Sheet-like expansion of macrophages in the lamina propria without granulomas
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What distinguishes M. avium from Whipple disease?
M. avium is acid-fast
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What is the etiology of gastrointestinal tuberculosis?
Caused by Mycobacterium tuberculosis, Mycobacterium bovis, or Mycobacterium avium
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Where is gastrointestinal tuberculosis endemic?
Areas like India and Pakistan
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What is the pathogenesis of Norovirus?
Involves ingestion or inhalation of as few as 10 viral particles
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What is the etiology of gastroenteritis outbreaks?
Caused by Norovirus (Norwalk virus)
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What is the common cause of severe childhood diarrhea?
Rotavirus is the most common cause
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How does Rotavirus affect the intestine?
Infects and destroys mature enterocytes, leading to loss of absorptive function
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What is the pathogenesis of Ascaris lumbricoides?
Ingested eggs hatch, larvae penetrate the mucosa, migrate to liver and lungs
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How is Ascaris lumbricoides transmitted?
Spread by human fecal-oral contamination
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What is the pathogenesis of Strongyloides?
Larvae penetrate skin, travel to lungs, then to intestines where they mature
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Where are Strongyloides commonly found?
Widely found in tropical and subtropical regions
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What causes Strongyloides infections?
Strongyloides larvae
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Where are Strongyloides infections widely found?
In tropical and subtropical regions worldwide
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Who may develop overwhelming infections from Strongyloides?
Immunocompromised individuals
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How is infection initiated by hookworms?
By larval penetration of the skin
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What do adult hookworms do in the duodenum?
Suck blood and reproduce
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How is hookworm infection diagnosed?
By detecting the eggs in stool
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What are the two main species of hookworms?
Necator americanus and Ancylostoma duodenale
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How many individuals are infected by hookworms worldwide?
More than 500 million
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What is a leading cause of iron deficiency anemia?
Hookworm infection in low-resource parts of the world
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How does Giardia lamblia infect the host?
By ingestion of cysts
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What do trophozoites of Giardia lamblia cause?
Microvillous damage and apoptosis of small-intestinal epithelial cells
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What is the microscopic appearance of Giardia lamblia?
Pear-shaped trophozoites
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How is Giardia lamblia spread?
By fecally contaminated water or food
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What is the most common pathogenic parasite in humans?
Giardia lamblia
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What does Cryptosporidium cause in the small bowel?
Secretory diarrhea and malabsorption
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How are Cryptosporidium organisms diagnosed?
By identifying organisms in stool preps
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What is a major source of Cryptosporidium infections?
Contaminated public water supplies
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How many deaths per year is Cryptosporidium responsible for?
As many as 200,000 deaths
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What type of ulcers do Entamoeba histolytica cause?
Flask-shaped ulcers
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What do Entamoeba histolytica amebae do to the colonic epithelium?
Induce apoptosis and invade crypts
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What can Entamoeba histolytica lead to in the liver?
Liver abscesses
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What can be seen on a trichrome stain of Entamoeba histolytica?
Amebae that have phagocytosed red cells
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What is the etiology of the inflammatory reaction described?
Caused by the protozoan Entamoeba histolytica
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How is Entamoeba histolytica spread?
By fecal-oral transmission
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Where is Entamoeba histolytica primarily found?
In low-resource parts of the world with poor sanitation
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What are common symptoms of Entamoeba histolytica infection?
Abdominal pain, bloody diarrhea, weight loss
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What can Entamoeba histolytica lead to?
Acute necrotizing colitis and megacolon
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What characterizes Angiodysplasia?
Malformed submucosal and mucosal blood vessels
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Where does Angiodysplasia most often occur?
In the cecum or right colon
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What age group is most affected by Angiodysplasia?
Usually presents after the sixth decade of life
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What percentage of the adult population is affected by Angiodysplasia?
Affects less than 1% of the adult population
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What is the pathogenesis of hemorrhoids?
Dilated anal and perianal collateral vessels
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What causes the development of hemorrhoids?
Due to elevated venous pressure within the hemorrhoidal plexus
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What are common predisposing factors for hemorrhoids?
Constipation, straining, pregnancy, portal hypertension
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What is the prevalence of hemorrhoids in the population?
Affects about 5% of the population
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What symptoms do hemorrhoids often manifest with?
Pain and self-limited rectal bleeding (bright red blood)
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What is the pathogenesis of intussusception?
A segment of the intestine telescopes into the distal segment, leading to obstruction and potentially infarction due to mesenteric vessel compression.
What are the morphological features of intussusception?
Involves an invaginated segment of the intestine, compressing its mesentery.
What is the etiology of intussusception in children?
Usually no underlying anatomical defect; may be associated with viral infections and rotavirus vaccines.
What is the epidemiology of intussusception?
Most common cause of intestinal obstruction in children under 2 years.
What is the pathogenesis of Hirschsprung Disease?
Congenital defect in colonic innervation due to disruption of neural crest cell migration.
What is the morphology of Hirschsprung Disease?
Aganglionic region may appear normal or contracted; proximal colon undergoes progressive dilation.
How is Hirschsprung Disease diagnosed microscopically?
By histological confirmation of the absence of ganglion cells in the affected segment.
What is the etiology of Hirschsprung Disease?
Congenital defect involving neural crest cell migration; associated with genetic mutations and trisomy 21.
What is the epidemiology of Hirschsprung Disease?
Occurs in approximately 1 in 5000 live births; more common in males.
What is the pathogenesis of abdominal hernia?
Weakness in the peritoneal cavity wall allows protrusion of a serosa-lined pouch, leading to potential incarceration and strangulation.
What is the morphology of an abdominal hernia?
A serosa-lined pouch protruding through a defect in the peritoneal cavity wall.
What is the etiology of abdominal hernias?
Commonly occur through inguinal and femoral canals, umbilicus, or surgical scars.
What are the two major mechanical causes of intestinal obstruction?
What is the pathogenesis of Ischemic Bowel Disease?
What are the vulnerable areas in Ischemic Bowel Disease?
What is the morphology of Ischemic Bowel Disease?
What characterizes acute ischemia microscopically?
What leads to sigmoid diverticulitis?
What is the morphology of diverticula in the sigmoid colon?
What are diverticula?
Pouches (0.5-1 cm) in the sigmoid colon with a thin wall.
What is the microscopic appearance of diverticula?
Protrusion of mucosa and submucosa through muscularis propria.
What are the causes of diverticula?
Elevated intraluminal pressure, Western diet, sedentary lifestyle.
What is the epidemiology of diverticula?
Rare under 30; 50% prevalence in adults over 60 in Western populations.
What causes Cystic Fibrosis?
Mutations of the CFTR gene affecting ion transport.
What is the pathogenesis of Cystic Fibrosis?
Leads to inadequate luminal hydration and exocrine pancreatic insufficiency.
What is the microscopic appearance in Cystic Fibrosis?
Duct obstruction and tissue damage in the pancreas.
What triggers Celiac Disease?
Ingestion of gluten in genetically predisposed individuals.
What are the morphological features of Celiac Disease?
Crypt hyperplasia, villous atrophy, increased intraepithelial lymphocytes.
What is the epidemiology of Celiac Disease?
Worldwide prevalence of about 1%; manifests in childhood and adulthood.
What is the onset age for Celiac Disease in children?
Between 6 and 24 months after gluten introduction.
What is the common age range for Celiac Disease onset in adults?
Between 30 and 60 years of age.
What is Environmental Enteric Dysfunction?
A syndrome of impaired intestinal function.
What causes malabsorption in Environmental Enteric Dysfunction?
Small intestinal colonization by toxigenic coliform bacteria.
What does a small intestinal biopsy show in Environmental Enteric Dysfunction?
Blunted villi and chronic inflammation.
What is a common microscopic finding in Environmental Enteric Dysfunction?
Similar to celiac disease: blunted villi and chronic inflammation.
Where is Environmental Enteric Dysfunction most prevalent?
Sub-Saharan Africa, northern Australia, southern India, and poor areas in South America and Asia.
What is Lactase Deficiency?
Inability to digest lactose due to insufficient lactase enzyme.
What causes osmotic diarrhea in Lactase Deficiency?
Unabsorbed lactose exerts an osmotic force in the intestinal lumen.
What is Congenital lactase deficiency?
A rare autosomal recessive disorder caused by mutations in the lactase gene.
What is the prevalence of acquired lactase deficiency?
Affects roughly two-thirds of the world’s population.
What is Abetalipoproteinemia?
A rare autosomal recessive disease marked by inability to secrete triglyceride-rich chylomicrons.
What is a characteristic finding in peripheral blood smears in Abetalipoproteinemia?
Presence of acanthocytic red cells (spur cells).
What are the two types of Microscopic Colitis?
Collagenous colitis and lymphocytic colitis.
What characterizes collagenous colitis?
Presence of a dense subepithelial collagen layer.
What is a symptom of both types of Microscopic Colitis?
Chronic, nonbloody, watery diarrhea without weight loss.
What is the histological difference between collagenous colitis and lymphocytic colitis?
What is the morphology of collagenous colitis?
Typically normal radiologic and endoscopic studies.
What are the microscopic features of collagenous colitis?
What is the etiology of lymphocytic colitis?
Idiopathic, associated with celiac disease and autoimmune diseases.
Who is primarily affected by collagenous colitis?
Middle-aged and older women.
What is the pathogenesis of graft-versus-host disease?
Donor T cell-mediated damage to recipient’s epithelial cells after transplantation.
What is a common microscopic finding in graft-versus-host disease?
Epithelial apoptosis, especially of crypt cells.
What are the causes of infectious enterocolitis?
Bacteria, viruses, and parasites.
What are some bacterial causes of infectious enterocolitis?
What is the global impact of infectious enterocolitis?
More than 1 million deaths annually, >10% in children under 5.
What is the pathogenesis of cholera?
Vibrio cholerae produces cholera toxin, increasing cAMP and chloride ion outflow into the gut lumen.
What activates the cystic fibrosis transmembrane conductance regulator (CFTR)?
Increased cAMP binds and activates CFTR.
What is the result of CFTR activation?
Massive outflow of chloride ions into the gut lumen.
What does the outflow of chloride ions cause?
Creates an osmotic gradient, leading to massive secretory diarrhea.
What is the morphology of mucosal biopsy specimens in cholera?
Show only minimal morphologic alterations.
What bacteria causes cholera?
Caused by Vibrio cholerae.
How is cholera primarily transmitted?
Through contaminated drinking water.
What is a common symptom of severe cholera?
Rapid dehydration, shock, and potential death.
What causes Campylobacter Enterocolitis?
Caused by Campylobacter jejuni.
What are the virulence factors of Campylobacter jejuni?
Includes motility, adherence, toxin production, and invasion.
What is the microscopic appearance of Campylobacter Enterocolitis?
Characterized by prominent lamina propria and intraepithelial neutrophil infiltrates.
What is a common source of Campylobacter infections?
Associated with ingestion of raw or undercooked meat.
What is a major epidemiological fact about Campylobacter?
A common cause of acute diarrhea worldwide.
What is the pathogenesis of Shigellosis?
Shigella organisms resist stomach acid and infect epithelial cells.
What does Shiga toxin do?
Inhibits eukaryotic protein synthesis and causes host cell death.
What is the morphology of Shigellosis?
Infections are most prominent in the rectosigmoid colon.
What is the etiology of Shigellosis?
Caused by Shigella (gram-negative, nonmotile bacteria).
How is Shigellosis transmitted?
Highly transmissible via the fecal-oral route.
What is a significant burden of Shigellosis?
A common cause of bloody diarrhea (dysentery).
What are the annual global cases of E. coli infections?
Approximately 170 million cases
What is the annual death toll from E. coli infections?
About 160,000 deaths
What syndrome can be caused by EHEC?
Hemolytic uremic syndrome
What toxin does ETEC produce?
Heat-labile toxin and heat-stable toxin
What does EPEC cause in the intestines?
Local loss (effacement) of microvilli
What type of diarrhea does EHEC cause?
Can cause dysentery
What characterizes EIEC infection?
Invasion of gut epithelial cells
How does EAEC cause symptoms?
By producing heat-labile and Shiga-like toxins
What is a principal cause of traveler’s diarrhea?
ETEC
What is the main cause of nontyphoid salmonellosis?
Salmonella enteritidis
What is a common symptom of Salmonellosis?
Diarrhea, nausea, vomiting, fever
How is nontyphoid Salmonella typically transmitted?
Through contaminated food
What is the annual incidence of Salmonellosis in the U.S.?
Over 1 million cases
What causes Typhoid fever?
Salmonella typhi and Salmonella paratyphi
What happens to Peyer patches in Typhoid fever?
They enlarge into plateau-like elevations
What type of ulcers are formed in the ileum due to Typhoid fever?
Oval ulcers oriented along the long axis
What are the causes of typhoid fever?
What are the morphological features of typhoid fever?
What is the microscopic appearance in typhoid fever?
What is the epidemiology of typhoid fever?
What is the pathogenesis of pseudomembranous colitis?
What are the morphological features of pseudomembranous colitis?
What is the microscopic appearance of pseudomembranous colitis?
What causes mycobacterial infections in the GI tract?
What is the morphology of mycobacterial infections?
What is the microscopic appearance in mycobacterial infections?
What are the causes of granulomas with caseous necrosis?
What is the common presentation of M. avium in immunocompromised patients?
Sheet-like expansion of macrophages in the lamina propria without granulomas
What distinguishes M. avium from Whipple disease?
M. avium is acid-fast
What is the etiology of gastrointestinal tuberculosis?
Caused by Mycobacterium tuberculosis, Mycobacterium bovis, or Mycobacterium avium
Where is gastrointestinal tuberculosis endemic?
Areas like India and Pakistan
What is the pathogenesis of Norovirus?
Involves ingestion or inhalation of as few as 10 viral particles
What is the etiology of gastroenteritis outbreaks?
Caused by Norovirus (Norwalk virus)
What is the common cause of severe childhood diarrhea?
Rotavirus is the most common cause
How does Rotavirus affect the intestine?
Infects and destroys mature enterocytes, leading to loss of absorptive function
What is the pathogenesis of Ascaris lumbricoides?
Ingested eggs hatch, larvae penetrate the mucosa, migrate to liver and lungs
How is Ascaris lumbricoides transmitted?
Spread by human fecal-oral contamination
What is the pathogenesis of Strongyloides?
Larvae penetrate skin, travel to lungs, then to intestines where they mature
Where are Strongyloides commonly found?
Widely found in tropical and subtropical regions
What causes Strongyloides infections?
Strongyloides larvae
Where are Strongyloides infections widely found?
In tropical and subtropical regions worldwide
Who may develop overwhelming infections from Strongyloides?
Immunocompromised individuals
How is infection initiated by hookworms?
By larval penetration of the skin
What do adult hookworms do in the duodenum?
Suck blood and reproduce
How is hookworm infection diagnosed?
By detecting the eggs in stool
What are the two main species of hookworms?
Necator americanus and Ancylostoma duodenale
How many individuals are infected by hookworms worldwide?
More than 500 million
What is a leading cause of iron deficiency anemia?
Hookworm infection in low-resource parts of the world
How does Giardia lamblia infect the host?
By ingestion of cysts
What do trophozoites of Giardia lamblia cause?
Microvillous damage and apoptosis of small-intestinal epithelial cells
What is the microscopic appearance of Giardia lamblia?
Pear-shaped trophozoites
How is Giardia lamblia spread?
By fecally contaminated water or food
What is the most common pathogenic parasite in humans?
Giardia lamblia
What does Cryptosporidium cause in the small bowel?
Secretory diarrhea and malabsorption
How are Cryptosporidium organisms diagnosed?
By identifying organisms in stool preps
What is a major source of Cryptosporidium infections?
Contaminated public water supplies
How many deaths per year is Cryptosporidium responsible for?
As many as 200,000 deaths
What type of ulcers do Entamoeba histolytica cause?
Flask-shaped ulcers
What do Entamoeba histolytica amebae do to the colonic epithelium?
Induce apoptosis and invade crypts
What can Entamoeba histolytica lead to in the liver?
Liver abscesses
What can be seen on a trichrome stain of Entamoeba histolytica?
Amebae that have phagocytosed red cells
What is the etiology of the inflammatory reaction described?
Caused by the protozoan Entamoeba histolytica
How is Entamoeba histolytica spread?
By fecal-oral transmission
Where is Entamoeba histolytica primarily found?
In low-resource parts of the world with poor sanitation
What are common symptoms of Entamoeba histolytica infection?
Abdominal pain, bloody diarrhea, weight loss
What can Entamoeba histolytica lead to?
Acute necrotizing colitis and megacolon
What characterizes Angiodysplasia?
Malformed submucosal and mucosal blood vessels
Where does Angiodysplasia most often occur?
In the cecum or right colon
What age group is most affected by Angiodysplasia?
Usually presents after the sixth decade of life
What percentage of the adult population is affected by Angiodysplasia?
Affects less than 1% of the adult population
What is the pathogenesis of hemorrhoids?
Dilated anal and perianal collateral vessels
What causes the development of hemorrhoids?
Due to elevated venous pressure within the hemorrhoidal plexus
What are common predisposing factors for hemorrhoids?
Constipation, straining, pregnancy, portal hypertension
What is the prevalence of hemorrhoids in the population?
Affects about 5% of the population
What symptoms do hemorrhoids often manifest with?
Pain and self-limited rectal bleeding (bright red blood)
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