Ch 17 Robbins- SI and Colon Flashcards
What is the most frequent cause of intestinal obstruction worldwide?
What is the most common cause in the USA?
What is the most common cause in children less than 2?
Which of the above due to fibrous bridges creating closed loops through which viscera may slide and become entrapped?
Which of the above can be caused by the rotavirus vaccine leading to reactive hyperplasia of Peyer’s patches?
1) Hernias
2) Adhesions
3) Intussusception
4) Adhesions
5) Intussusception
Volvulus lead to complete twisting of a bowel loop about its mesenteric vascular base that can lead to?
Toxic megacolon
What is the most common acquired GI emergency of neonates and presents when oral feeding is initiated?
Necrotizing Enterocolitis (NEC)
Malformed tortuous, ectatic dilations of veins, venules and capillaries in mucosa and submucosa characterizes?
Where is it most common?
It is involved in 20% of what major bleeds?
1) Angiodysplasia
2) Cecum or ascending colon
3) Lower GI bleeds
What is the hallmark of malabsorption and usually presents as chronic diarrhea?
Steatorrhea
Which category of diarrhea causes isotonic (to plasma) stool?
Which has purulent, blood stools?
1) Secretory
2) Exudative
Which HLA are associated with Celiac disease?
What component of gluten contributes to the dz?
What condition is found in 10% of patients due to anti-gluten antibodies cross-reacting with BM proteins?
1) Class II HLA-DQ2, HLA-DQ8
2) α-gliadin
3) Dermatitis herpetiformis
How is celiac dz diagnosed?
1) Increased CD8 T-cells
2) Villous atrophy
3) IgA Abs to tissue transglutaminase (tTG)
Abetalipoproteinemia presents in infancy and is a rare autosomal recessive mutation of?
What does it lead to?
Acanthocytic red cells (burr cells) in peripheral blood smears are found due to?
1) Microsomal triglyceride transfer protein (MTP)
2) Intracellular lipid accumulations
3) Inability to absorb essential FA
What watershed zone is most vulnerable to Ischemic bowel disease?
Splenic flexure between superior and inferior mesenteric arteries
What is the characteristic morphology of ischemic bowel disease?
Epithelial surface sloughs off
How does the severe familial form of autoimmune enteropathy present?
It is due to what mutation?
1) IPEX: immune dysregulation, polyendocrinopathy, enteropathy, X-linked
2) FOXP3
What is congenital lactase deficiency caused by?
What is acquired lactase deficiency caused by?
1) Autosomal recessive (loss of function) mutation in lactase gene
2) Downregulation of lactase gene expression often following a viral or bacterial infection
Enteric viruses commonly cause pediatric infectious diarrhea leading to?
Severe dehydration and metabolic acidosis
What comma-shaped, gram negative bacteria causes rice water diarrhea?
Vibrio cholera
What comma-shaped, flagellated, gram negative bacteria causes traveler’s diarrhea and food poisoning?
Campylobacter jejuni
Campylobacter jejuni has neutrophils in the submucosa and crypts which may cause?
What genotype can cause reactive arthritis?
What can it cause due to LPS cross reactivity?
1) Crypt abscesses
2) HLA-B27
3) Guillain-Barre syndrome
What non-encapsulated, non-motile, facultative anaerobe is the most common cause of bloody diarrhea?
Shigella
How is shigella transmitted?
Where does the disease primarily occur?
What does the serotype 1 toxin cause?
1) Fecal-oral
2) Left colon
3) Hemolytic uremic syndrome
What complications does shigella cause in HLA-B27 males 20-40 years old?
Sterile reactive arthritis, urethritis, conjunctivitis
Salmonella is a gram negative bacillus that has flagellin which interacts with what TLR?
TLR5
What does salmonella infections cause?
Plateau-like elevations of peyer’s patches in terminal ileum
Gallbladder colonization with salmonella typhi or paratyphi can be associated with?
Gallstones and a chronic carrier state
What bacteria is associated with ingestion of pork, raw milk and contaminated H2O?
Yersinia
Because yersinia has a tropism for the ileum, appendix and right colon what does it mimic?
The organisms proliferate extracellularly in lymphoid tissue leading to?
Because overlying mucosa can become hemorrhagic and ulcerated, with neutrophilic infiltrates and granulomas, what can it mimic?
What enhances virulence and stimulates systemic dissemination?
1) Appendicitis
2) LN and Peyer patch hyperplasia
3) Crohn’s disease
4) Iron
What is the principal cause of traveler’s diarrhea?
How is the diarrhea characterized?
1) Enterotoxigenic E. coli (ETEC)
2) Secretory, non-inflammatory
Which ETEC toxin activates AC which increases cAMP along with increase Cl- secretion?
Which increases cGMP?
1) Heat labile toxin
2) Heat stable toxin
What causes endemic diarrhea and diarrheal outbreaks in patients less than 2 years old?
Enteropathic E. coli (EPEC)
What allows detection and diagnosis of infection by EPEC?
Tir, a receptor for intimin
Tir produces attaching and effacing (A/E) lesions in which?
Proteins (i.e. Tir) necessary for creating A/E lesions are all encoded in the?
1) Bacteria attach tightly to the enterocyte apical membranes
2) Locus of enterocyte effacement (LEE)
Enterohemorrhagic E. coli (EHEC) is associated with what serotype that produce shiga like toxins?
O157:H7
O157:H7 is more likely to produce?
Outbreaks, bloody diarrhea, and HUS
Why are antibiotics contraindicated with EHEC, especially in children?
Because killing bacteria increases the amount of toxin released and enhances HUS
Which E. coli is bacteriologically similar to Shigella but does not produce toxins?
Enteroinvasive E. coli (EIEC)
EIEC invades epithelial cells which causes?
Acute self-limited colitis
Which E. coli has a unique stacked brick morphology when bound to epithelial cells?
Enteroaggregative E. coli (EAEC)
What does EAEC cause that is prolonged in AIDS patients?
Non-bloody diarrhea
Pseudomembranous colitis (PMC) is caused by?
What histopathology is pathognomonic?
1) Overgrowth of clostridium difficile due to antibiotic use
2) Damaged crypts that form pseudomembranes
What type of diarrhea does PMC cause?
What is the malabsorptive diarrhea due to?
How is it diagnosed?
1) Watery
2) Impaired lymphatic transport
3) C. difficile toxin in stool
Whipple disease is a rare, systemic condition due to?
Who is it most common in?
1) Actinomycete tropheryma whippelii
2) Caucasian males, particularly farmers
The morphoeic hallmark of Whipple disease is?
Dense accumulation of distended foamy macrophages in small intestine lamina propria
What is the clinical presentation of Whipple disease?
Triad of diarrhea, weight loss, and arthralgia
What is the most common cause of sporadic gastroenteritis in developed countries and the most common cause of acute gastroenteritis requiring medical attention?
Norovirus
What may we see pathologically with norovirus?
1) Villous shortening
2) Loss of brush border
3) Crypt hypertrophy
4) Lymphocytic infiltration
What is the most common cause of severe childhood diarrhea and diarrheal mortality worldwide?
Rotavirus
What risk is the rotavirus vaccine associated with?
What population is it contraindicated in?
1) Intussusception
2) Immunocompromised because it is live-attenuated
What effect does adenovirus have on the villi?
Villous atrophy
What is the most common parasitic pathogen and spreads through fecally contaminated water or food?
Giardia lamblia
Giardia contains a flagellate protozoan that has what action?
Decrease expression of brush border enzymes including lactase
What is characterized by chronic, relapsing abdominal pain, bloating, and changes in bowel habits without obvious gross or histological pathology?
Irritable bowel syndrome (IBS)
What is a chronic condition due to inappropriate mucosal immune responses to normal gut flora?
Irritable bowel disease (IBD)
What is the hygiene hypothesis that is associated with IBD?
Increasing incidence is due to improved food storage conditions, decreased food contamination, and changes in gut microbiome composition
What is a transmural inflammation that involves any area of the GI tract?
Crohn’s disease
What distinct morphology is seen with Crohn’s?
1) Skip lesions
2) Punched out aphthous ulcers
3) Cobblestone appearance
4) Villous blunting
5) Noncaseating granulomas
Skip lesions which are seen in crohn’s disease are separate, sharply delineated disease areas with?
Granular and inflamed serosa and adherent creeping mesenteric fat
Crohn’s disease onset is associated with?
What is there an increased risk of in patients with longstanding colon involvement?
What are there antibodies to?
1) Initiation of smoking
2) Adenocarcinoma
3) Saccharomyces cerevisiae
What is an inflammatory disease limited to the colon and rectum that affects only the mucosa and submucosa?
Ulcerative colitis
What distinct morphology is seen with ulcerative colitis?
1) Disease of continuity (no skip lesions)
2) Crypt abscesses
3) No thickening, strictures, fissures, or granulomas
What are some potential complications with ulcerative colitis?
1) Toxic megacolon
2) Increased risk of colonic adenocarcinoma
How does ulcerative colitis present clinically?
Intermittent attacks of bloody diarrhea with stringy, mucoid material
How does smoking affect patients with ulcerative colitis?
Smoking cessation may trigger it
Diversion colitis is a blind colon segment as the result of?
Surgical treatment that results in an ostomy
What do we see develop with diversion colitis?
What is the treatment for it?
1) Numerous mucosal lymphoid follicles
2) Re-anastomosis
What type of diarrhea is most common in GVHD?
Watery
What refers to small acquired pseudo-diverticular, flask-like outpouchings of the colonic mucosa and submucosa?
Sigmoid Diverticular Disease
Which polyps lack a stalk?
Which has a stalk?
1) Sessile
2) Pedunculated
What is the most common of all the polyps?
Neoplastic adenoma
Which polyps have no malignant potential?
Where is the most common location for them?
1) Hyperplastic polyps
2) Left colon
What are histological similar to hyperplastic polyps but are potentially malignant?
Sessile serrated adenoma
Inflammatory polyps can be part of solitary rectal ulcer syndrome that cause a triad of what syndomps?
1) Rectal bleeding
2) Mucus discharge
3) Inflammatory lesion on the anterior rectal wall
What are hamartomatous polyps due to?
What are they associated with?
1) Germline mutation in tumor suppressor genes or proto-oncogenes
2) Increased risk of cancer
What are focal hamartomatous malformations of small intestine and colon mucosa (mainly rectum)?
Juvenile polyps (aka retention polyps)
What can happen to juvenile polyps in the stomach and small bowel?
Undergo malignant transformation
What may be the initiating event of juvenile polyps?
What is the most common mutation causing it?
What does the mutation cause molecularly?
1) Mucosal hyperplasia
2) SMAD4
3) Affects TGFβ signaling
Peutz-Jeghers Syndrome is an autosomal dominant syndrome that presents as a median age of 11 years with?
It causes a markedly increased risk of?
About 50% of patients with Peutz-Jeghers Syndrome have what loss of function mutation?
1) Multiple GI hamartomatous polyps and mucocutaneous hyperpigmentation
2) Malignancy
3) STK11
What condition if presented with Peutz-Jeghers Syndrome will result in guaranteed malignancy?
What should be done as prevention?
1) Familial adenomatous polyposis (FAP)
2) Prophylactic colectomy
What are the most common neoplastic polyps?
Colonic adenomas
Colorectal adenomas are characterized by the presence of?
Epithelial dysplasia
What is the most important characteristic of adenomas that correlate with the risk of malignancy?
Polyp size (larger the size the higher the risk)
Despite malignant potential, sessile serrated lesions lack?
Where are they most common?
1) Typical cytologic features of dysplasia
2) Right colon
What occurs when dysplastic cells invade the lamina propria or muscularis mucosa?
What is its metastatic potential?
1) Intramucosal carcinoma
2) Little or no metastatic potential due to lack of lymphatic channels in colonic mucosa
What crosses into the submucosa and accesses lymphatics causing a risk of metastasis?
Invasive adenocarcinoma
What is an autosomal dominant disorder in which patients develop numerous colorectal adenomas as teenagers?
What is it caused by?
1) Familial adenomatous polyposis (FAP)
2) APC mutation
What develops in 100% of untreated FAP patients (especially in 50 y/o)?
Colorectal adenocarcinoma
If there is no APC mutation in FAP patients, they may have biallelic mutations of?
MYH (base-excision repair gene)
What is the most common syndromic form of colon cancer?
Hereditary nonpolyposis colorectal cancer (HNPCC; Lynch Syndrome)
HNPCC most often occurs under the age of 50 and often found in?
It is caused by mutations in?
1) Right colon (ascending colon)
2) MSH2 or MLH1 (mismatch repair genes)
What is the most common malignancy of the GI tract?
Colonic adenocarcinoma
What pathway is affected in adenocarcinoma?
APC/β-catenin pathway
Which sided adenocarcinoma presents with fatigue and weakness due to iron deficient anemia?
What sided adenocarcinoma can produce occult bleeding, changes in bowel habits or cramping?
1) Right sided adenocarcinoma
2) Left sided adenocarcinoma
What are the most important prognostic factors of adenocarcinoma?
Depth of invasion and presence of lymph node metastases
Where is adenocarcinoma metastases most common to?
Liver
