chapter17 GIT Flashcards
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Congenital abnormalities GIT
AtresiaDuplicationsFistula
Most common congenital is ______. Developmentally incomplete
Atresia
It rsults to mechanical obstruction due to replacement of noncanalized cord.
Esophageal atresia
Atresia most commonly occurs in the _______. It is usually assoc with a _____ connecting the upper and lower esophageal pouches to a bronchus or trachea.
Near tracheal BifucationFistula
Is less common than esophageal atresia but it frequently involves the duodenum and is characterized by a segment of bowel lacking a lumen.
Intestinal Atresia
It is an incomplete form of atresia in which the lumen is reduced in caliber as a result of fibrous thickening of the wall resulting in partial or complete obstruction.Most commonly affected is in the esophagus and small intestine.
Stenosis
The most common congenital intestinal atresia due to failure of the cloacal diaphragm to involute.
Imperforate anus
Are saccular or congenital cystic masses that contain redundant smooth muscle layers. May be present in the esophagus,intestines or colon.
Congenital duplication cyst
What is the tx of ménétrier dse
- Supportive 2. IV albumin 3. Parenteral nutritionSevere cases: gastrectomy
A disease caused by gastrin-secreting tumors, gastrinomas, that are most commonly found in the small intestine and pancreas.Px often present with duodenal ulcer and chronic diarrhea.Within the stomach the most remarkable feature is DOUBLING OXYNTIC MUCOSAL THICKNESS DUE TO A FIVEFOLD INCREASE IN PARIETAL CELLS
Zollinger Ellison Syndrome
Gastric polyps and tumors
- Inflammatory and hyperplastic polyps2. Fundic gland polyps3. Gastric adenoma4.gastric adenocarcinoma5. Lymphoma6. Carcinoid tumor7. Gastrointestinal stromal tumor
Nodules or masses that project above the level id the surrounding mucosa and are i.d in up to 5% of upper GI endoscopiesIt may develop as a result of epithelial or stromal cell hyperplasia, inflammation, ectopia or neoplasia.
Polyps
Approx 75% of all gastric polypsAre most common in indiv bet 50-60 yo.Polyps that usually develop in assoc with chronic gastritis, which initiates the injury and reactive hyperplasia that leads to polyp growth.In indiv with H.pylori, regresses after removal of insult.
Inflammatory and hyperplastic polyps
Occur sporadically and in indiv with FAP.Increased gastric secretion, in response to reduced gastric acidity, and the resulting glandular hyperplasia.5x more commom in women and an average of 50y0.May be asymptomatic or assoc with nausea, vomiting, or epigastric pain.Morphology:Occur in gastric body and fundusWell circumscribed lesions with smooth surfaceSingle or multipleCystically dilated irregular glands lined by flattened parietal and chief cellsInflammation is typically absent or minimal.
Fundic gland polyps
10% of all gastric polyps.Incidence increases progressively with age. Bet 50-603x more in malesLike fundic gland polyp it is assoc with FAPRisk of gastric ca is related to the size of lesion and is elev in leasion greater than 2cm in diameter
Gastric adenoma
Morphology:Usually solitary lesions less than 2cm in diameterMost commonly loc in the antrumMajority are composed of intestinal-type columnar epithelium.
Gastric adenoma
Is the most common malignancy in the stomach.90% of all gastric ca.Early symptoms resemble those of chronic gastritis, including,Dysphagia, dyspepsia, and nausea.Often discovered at advanced stages when symptoms such as wt loss, anorexia, altered bowel ha its, anemia a s hemorrhage trigger further diagnostic evaluation.It is. Ore common in lower socioeconomic status and in indiv with multifocal mucosal atrophy and intestinal metaplasia. PUD doesnt impart as risk factor except to those who had partial gastrectomy for PUD.Majority is not inherited.
Gastric adenocarcinoma
What is the pathogenesis in gastric adenocarcinoma?
Germline mutations in CDH1 which encodes E-cadherin , a protein that contributes to epithelial intercellular adhesion are associated with familial gastric ca of which is a diffuse type.
What is the pathogenesis of intestinal-type gastric ca?
Mutation in beta-catenin, a protein that binds to both E-cadherinand adenomatous polyposis coli ( APC ), as well as microsatellite instability and hypermethylationof several genes including TGF B RII, BAX, IGFR II and p16 /INK4.
Morphology charac:Irreg enlargement of gastric rugae.Some areas appear polypoid.Enlarged rugae present in body and fundus except antrum( gen spared)Most characteristic feature: HYPERPLASIA OF FOVEOLAR MUCOUS CELLS.THe glands are elongated with CORK-SCREW appearance and cystic dilation is common.Inflammation is only modest although some cases show marked intraepithelial lymphocytosis.Diffuse or patchy glandular atrophy, evident as hypoplasia or parietal and chief cell is typical
Ménétrier dse
2 diseases associated in hypertrophic gastrophaties
- Ménétrier dis2. Zollinger ellison syndrome
Uncommon diseases charac by GIANT CEREBRIFORM ENLARGEMENT OF THE RUGAL FOLDS due to epithelial hyperplasia W/O inflammation.As expected they are linked to excessive GF release
HYPERTROPHIC GASTROPHATIES
Rare d/oCaused by x’ss secretion TGF-alphaCharac by: diffuse hyperplasia of foveolar epithelium of the. Body and fundus and hyperproteinemia due to protein losing enteropathySecondary symptom: wt loss, diRrhea, peripheral edema.Pathologic feature in children same in adult but pedia dse is self- lim and often follows respi infection.Risk of gastric adenocarcinoma is ⬆️ in adult.
Ménétrier dse
Intestinal obstruction occurs at any level but which is commonly affected and why?
Small intestine because of its narrow lumen
what are the collection of intestinal obstruction?
- hernias
- intussuception
- volvulus
- adhesions
this account for 80 % of intestinal obstructions
volvulus
how many percent does tumors account for intestinal obstruction?
10-15%
what are the clin manifestation of intestinal obstruction?
abdomina pain and distention
vomiting
constipation
What is the weakness or defect in the wall of the peritoneal cavity that may permit protrusion of a serosa-lined pouch of peritoneum
hernial sac
Acquired hernias most commonly occured in the?
It is via?
anterior
inguinal, femoral canals, umbilicus, or sites of surgical scars
The resultant stasis and edema increases the bulk of the herniated loop, leading to permanent entrapment called _______. In which overtime, arterial, and venous compromise ______ develpps that can result in infarction.`
incarceration
strangulation
Surgical procedures, infections, or other causes of peritoneal inflammation, such as endometriosis, may result in development of _______ between bowel segmens, the abdomina wall and operative sites.
adesions
Complete twisting of a loop bowel about its mesenteric base of attachment is called _____ and produces both luminal and vascular compromise. Thus presentation includes features of obstruction and infarction. It occurs most often in large redundant loops of sigmoid colon, followed in frequency by the :
cecum
small bowel
stomach
or rarely transverse colon.
Because this is rare, it is often missed clinically
volvulus
It occurs when a segment of the intestine, constricted by a wave of peristalsis, telescopes into te immediately distal segment. Once trapped, the invaginated segment is propelled by peristalsis and pulls the mesentery along. If left untreated may result in or progress into intestinal obstruction, compression of mesenteric vessels and infarction.
When encountered in infants no underlying cause but come cases are associated with_______.
In older children and adults an intraluminal mass or tumor generally serves as the point of traction that causes this.
Intussusception
Rota virus
Acute compromise of any major vessel can lead to infarction of several meters of intestine. Damage can range from______.
- mucosal infarction
- mural infarction
- transmural infarction
Infarction extending no deeper than te muscularis mucosa
mucosal infarction
Infarction extending of mucosa to submucosa
mural infarction
infarction involving all three wall layers
transmural infarciton
Mucosal or mural infarctions are often secondary to____
acute or chronic hypoperfusion
transmural infarciton is generally caused by _____
acute vascular obstruction
what are the two major variables in IBD?
- Time frame which it develops
- vessels affected
Intestinal segments at the end of their respective arterial supplies are particularly susceptible to iscemia. These are called_______ which includes:__________
Watershed zone
splenic flexure where the superior and inferior mesenteric arterial circulation ends
to a lesser extent the sigmoid colon andrecutm where inf mesenteric, pudendal and iliac arteries circulations end.
What is a morphologic signature of iscemic intestinal disease? why?
Surface epithelial atrophy or even necrosis and sloughing with normal or hyperproliferative crypts .
The reason is intestinal capillaries run alongside the glands, form the crypt to surface, before making a hairpin turn at the surface to empty into the post-capillary venules. This allows oxygenated blood to supply crypts but leaves the surce epithelium vulnerable to ischemic injury. This anatomy protects the crypts which contain the epithelial stem cells.
Microscopic examination showing ATROPHY OR SLOUGHING OF SURFACE EPITHELIUM. In contrast, crypts may be hyperproliferative. Inflammatory infiltrates are initially absent in acute ischemia nut neutrophils are recruited within hours of reperfusion. Chronic ischemia is accompanied by fibrous scarrring of the lamina propria and uncommonly stricture forms.
IBD
In acute phase of IBD bacterial superinfection and enterotoxin release may induce pseudomembrane formation that can resemble ______
C. difficile- associated pseudomembranous colitis
It tends to occur in older individual with coexisting cardiac or vulvular disease. Acute transmural infarction typically presents wit sudden abdominal pain and tenderness, sometimes accompanied by nausea, vomiting, bloody diarrhea, or grossly melanotic stool.
Patients may progress to shockand vascular collapse within hours as a result of blood loss. Peristaltic sound diminished or disappear and muscular spasm creates board- like rigidity of the abdomina wall.
These physical signs overlaps with other abdominal emergencies that results in delayed or missed diagnosis.
IBD
These themselves may not be fatal. However, may progress to more extensive infarction if the vascular supply is not restored by correction of the insult or in chronic dse by dev of adequate collateral supplies. Diagnosis is partially difficult since there may be a confusing array of nonspecific abdominal symptoms including intermittent bloody diarrhea and intestinal psuedo-obstruction.
Mucosal and mural infarction
May masquarade as IBD with episodes of bloody diarrhea interspesed with periods of healing
chronic ischemia
This causes iscemic GI dsew due to viral tropism for and infection of endothelial cells. This is a complication of an immunosuppressive therapy
CMV
This occurs when the GI tract is irradiated. In add to epitelial damage, radiation-induced vascular injury may be significant and produce changes that are similar to ischemic disease. The presence of BIZARRE “ RADIATION FIBROBLAST” within the stroma may provide important clue to the etiology. It manifest as anorexia, abdominal cramps, and a malabsorptive diarrhea while chronic radiation enteritis or colitis is often more indolent and may present as an inflammatory colitis.
Radiation enterocolitis
Is an acute do of the small and large intestines that can result in transmural necrosis. It is the most common acquired GI emergency of neonates, particularly those who are premature of LBW and occurs most oftenat the time of oral feeding.
NEC
Characterized by malformed submucosal and mucosal blood vessels. It occurs most often in the CECUM or RIGHT colon because cecum has the largest diameter that develops tha greatest wall tension. It is usally after the 6th decade of life. Prevalence is < 1 % in adult, it accounts for 20 % major episodes of lower intestinal bleeding; intestinal hemorrage may be chronic and intermittent, acute and massive. Pathogenesis is attributed to mechanical and congenital factors.
angiodysplasia
Presents most commonly as chronic diarrhea characterized by defective absorption of fats, fat- and water- soluble vit ,proteins, carbohydrates,electrolytes and mineral and water.
Malabsorption
It is accompanied by wt loss, anorexia, abdominal distention, borborygmi and muscle wasting.
chronic malabsorption
Steatorrhea is the hallmark of this condition which is characterized by excessive fecal fat and bulky, frothy greasy, yellow or clay colored stool.
Malabsorption
Malabsorption results from distrubance of the ff phases:
- intraluminal digestion
- terminal digestion
- transepithelial digestion
- lymphatic transport
The phase of digestion in which fats, protein, CHOH are broken down intor forms suitable for absorption.
intraluminal digestion
The phase that involves the hydrolysis of carboydrates and peptieds by dissacharides and peptidases, respectively in the brush boder of the mall intesinal mucosa.
terminal digestion
Phase where nutritiens, electrolytes are transported across and processed within the small intetinal epithelium.
transepithelial digestion
transport of absorbed lipids
lymphatic transport
What are the general sypmtoms of malabsorption
diarrea ( nutrient malabsorption and excessive intestinal secretion)
flatus
abdominal pain
and weight loss.
It is defined as an increase in stool mass, frequency or fluidity, typically greater than 200g per day. In severe cases, stool volume can exceed 14 L per day and without fluid resusscitation can result in death.
diarrhea
Painful, bloody, small volume diarrhea is known as _____
dysentery
What are the 4 major categories of diarrhea?
- secretory diarrhea
- osmotic diarrhea
- malabsorptive diarrhea
- exudative diarrhea
Isotonic stool and persist during fasting
secretory diarrhea
Excessive osmotic forces exerted by unabsorbed luminal solutes. The diarrhea fluid is more than 50 mOsm more concentrated than plasma and abates with fasting. An example is lactase deficiency.
Osmotic diarrhea
It follows generalized failures of nutient absorption and is associated with steatorrhea and is relieved by fasting
Malabsorptive diarrhea
It is due to inflammatory disease and characterized by purulent, bloody stools tat continue during fasting.
Exudative diarrhea
This is due to absence of CFTR, individuals have defects in intestinal chloride ion secretion. This interferes with bicarb, sodium and water secretion, ultimately resulting in defective luminal hydration.
Cystic Fibrosis
It is an immune-mediated enteropathy triggered by te ingestion of gluten-containing cereals, such a wheat, rye or barley, in genetically predisposed individuals. It is common in European and caucasian descent with a prevalence rate of 0.5% to 1%.
Celiac disease, celiac sprue or gluten-sensitive enteropathy.
This is a malabsorption that occurs almost exclusively in people living in or visiting the tropics, including Puerto Rico, the Caribbean, northen South America, West Africa, India and Southeast Asia. Histologic changes are similar to celiac disease, but toal villous atrophy is uncommon and tends to inolve the distal small bowel. The latter probably explains the freq of folate and vit B12 deficiencies with megaloblastic anemia. There is no definite casual organism but various infections including Cyclospora or enterotoxigenic bacteria have been suggested as etiologic factors.
Tropical Sprue
It is an X-linked do characterized by severe diarrhea and autoimmune disease that occurs most often in young children. There is a germline mutation in te FOXP3 gene which is located on the X chromosome.
Autoimmune enteropathy
What does IPEX stands for?
Immune dysregulation, polyendocrinopathy, enteropathy and X- linkage
What is the pathophysio of IPEX?
There is a germline mutation of FOXP3 which is located in X chromosome. FOXP3 is a transcriptor factor expressed in CD4+ regulatory T cells and individuals with IPEX and FOXP3 mutations have defective T-regulatory function.
Where is the disaccharide lactase located?
apical brus-border membrane of the villous
It is caused by mutation in the gene encoding lactase, is an autosomal recessive disorder. The disease is rare and presents as EXPLOSIVE DIARRHEA with watery, FROTHY stools and abdomina distention upon milk ingestion.
Congenital Lactase deficiency
It is a down regulation of lactase gene expression and is particularly common among native Americans, African Americans and Chinese populations. Disease presents after childhood, peraps reflecting the fact that , before farming of dairy animals, lactase was unnecessary after children stopped drinking mother’s milk
acquired lactase deficiency
This is a rare autosomal recessive disease characterized by an inability to secrete triglyceride-rich lipoprotein due to mutation in the microsomal triglyceride transfer protein ( MTP) that catalyzes transport of triglycerides, cholesterol esters and phospholipids. MTP-deficient are unable to export lipoproteins and free faty acids as a result that monoglycerides cant be assembled as chylomicrons and TG accumulate within the epithelial cells. This presents in infancy and clinical picture is dominated by failure to thrive, diarrhea and steatorrhea. There is presence of acanthocytic red cells (burr cells) in PBS.
ABETALIPOPROTEINEMIA
What are the infectious Enterocolitis?
- Cholera
- Campylobacter Enterocolitis
- Shigellosis
- Salmonellosis
- Typhoid Fever
- Yersina
- Eschericia Coli
- Pseudomembranous Colitis
- Whipple Disease
- Viral Enterocolitis
- Parasitic Enterocolitis
It is a comma -shaped , Gr negative bacteria, a diseases that as been endemic in the Ganges Valley of India and Bangladesh for all recorded history. It is primarily transmitted by contaminated drinking water. However, it can also be present in food and causes sporadic cases of sea-food associated disease in North America.
Vibrio cholera
There is a marked seasonal variation in most climates due to rapid growth of vibrio bacteria at warm temperature; the only animal resovoirs are______
shellfish and planktons
It is the most common cause of seafood- associated gastroenteritis in North America.
V. Parahaemolyticus
What virulence factor in V. cholerae is responsible for te bacterial detachment and shedding in stool.
Hemaglutinin
It is the most common bacterial enteric patogen in developed countires and is an important cause of traveler’s diarrea. Most infections are associated wit ingestion of improperly cooked chicken but outbreaks can also be caused by unpasteurized milk or contaminated water. The clinical presentation watery diarrhea , either acute or following an influenza-like prodrome is the primary symptom and dysentery develops in 15 % of patient.
Campylobacter enterocolitis
True or False. In Campylobacter enterocolitism, antibiotic therapy is required?
FALSE
Gr. Neg bacilli that were initially isolated during the Japanese red diarrhea epidemic of 1897. These are unencapsulated, nonmotile, facultative anaerobes that belong to the Enterobacteriacea and are closely related to enteroinvasive E.coli. Humans are the only known reservoir and they are the most common cause of bloody diarrhea.
Shigella
What are the four majour subgroup of E.coli
ETEC ( Enterotoxigenic E.coli)
EHEC ( Enterohemorrhagic E.coli)
EIEC ( Entero invasive E.coli)
EAEC ( Enteroaggregative E.coli)
These are the principal cause of traveller’s diarrhea that is most common un underdeveloped regions affecting children younger than 2 years of age are susceptible.
ETEC
In developed countries assoctiate with the consumption of inadequately cooked ground beef, sometimes from fast food. Contaminated milk and vegetables are also vehicles.
E.coli 0157:H7
These are organism that are bacteriologic similar to Shigella and are transmitted by person to person, food and water. These dont produce toxins but instead they cause to invade epithelial cells and cause nonspecific features of acute limited colitis.
Enteroinvasive E. coli
Identified on the absis of their uniques pattern of adherence to epithelial cells. It also cause traveller’s diarrhea. They attach to epithelial cell via ADHERENCE FIMBRIAE and are aided by dispersin, a bacterial surface protein that neutralizes the negative surface charge of LPS. It produces enterotoxin related to SHIGELLA and ETEC ST toxin
EAEC
Generally caused by ________________, is also known as antibioticassociated colitis or antibiotic-associated diarrhea. The latter terms apply to diarrhea developing during or after a course of antibiotic therapy and may be due to C. difficile as well as Salmonella, C. perfringens type A, or Staphylococcus aureus. The latter two organisms produce enterotoxins and are common agents of food poisoning.
Pseudomembranous colitis
Morphology. Fully developed_____ is accompanied by formation of pseudomembranes , made up of an adherent layer of inflammatory cells and debris at sites of colonic mucosal injury. While pseudomembranes are not specific and may occur in ischemia and necrotizing infections, the histopathology of this is striking. The surface epithelium is denuded, and the superficial lamina propria contains a dense infiltrate of neutrophils and occasional fibrin thrombi within capillaries. Superficially damaged crypts are distended by a mucopurulent exudate thatforms an eruption reminiscent of a volcano ( These exudates coalesce to form the pseudomembranes
pseudomembranous colitis
a rare, multivisceral chronic disease first described as intestinal
lipodystrophy. original case report described an individual with malabsorption, lymphadenopathy,and arthritis of undefined origin.
Postmortem examination demonstrated the presence of foamy macrophages and large numbers of argyrophilic rods in the lymph nodes, providing evidence that the disease was infectious.
Clinical symptoms occur because organism-laden macrophages accumulate within the small intestinal lamina propria and mesenteric lymph nodes, causing lymphatic obstruction. Thus, the malabsorptive diarrhea of Whipple disease is due to impaired
lymphatic transport.
Whipples Disease
The Gram-positive actinomycete, named ________, that is responsible for Whipple disease was identified by PCR in 1992 and finally
Tropheryma
whippelii
the malabsorptive diarrhea of Whipple disease is due to impaired
_________.
lymphatic transport
This is a disease is a dense accumulation of distended, foamy macrophages in the small intestinal lamina propria ( Fig. 17-30A ).
The macrophages contain periodic acid–Schiff (PAS)-positive, diastase-resistant granules that represent lysosomes stuffed with partially digested bacteria ( Fig. 17-30B ). Intact rodshaped bacilli can also be identified by electron microscopy ( Fig. 17-30C ). A similar infiltrate of foamy macrophages is present in intestinal tuberculosis ( Fig. 17-30D ), and in both diseases the organisms are PAS-positive.
The villous expansion caused by the dense macrophage infiltrate imparts a shaggy gross appearance to the mucosal surface. Lymphatic dilatation and mucosal lipid deposition account for the common endoscopic detection of white to yellow mucosal plaques. In this disease, bacteria-laden macrophages can accumulate within mesenteric lymph nodes, synovial membranes of affected joints, cardiac valves, the brain, and other
sites
Whipple disease
The morphologic hallmark of Whipple disease is a ________
dense accumulation of
distended, foamy macrophages in the small intestinal lamina propria
a rare, multivisceral chronic disease first described as intestinal lipodystrophy.
Its original case report described an individual with malabsorption, lymphadenopathy,
and arthritis of undefined origin. Postmortem examination demonstrated the presence of foamymacrophages and large numbers of argyrophilic rods in the lymph nodes, providing evidence Infectious Enterocolitis that the disease was infectious.
Clinical symptoms occur because organism-laden macrophages
accumulate within the small intestinal lamina propria and mesenteric lymph nodes, causing lymphatic obstruction. Thus, the malabsorptive diarrhea is due to impaired
lymphatic transport
Whipple’s Disease
The clinical presentation of is usually a triad of diarrhea, weight loss, andmalabsorption. Extraintestinal symptoms, which can exist for months or years before
malabsorption, include arthritis, arthralgia, fever, lymphadenopathy, and neurologic, cardiac, or
pulmonary disease.
Whipple disease
is a common cause of nonbacterial infectious gastroenteritis. [87] These are small icosahedral viruses with a single-stranded RNA genome that forms a genus within the Caliciviridae family. Norovirus causes approximately half of all gastroenteritis outbreaks worldwide and is a common cause of sporadic gastroenteritis in
developed countries. Local outbreaks are usually related to contaminated food or water, but person-to-person transmission underlies most sporadic cases.
Infections spread easily within schools, hospitals, nursing homes, and, most recently, cruise ships. Following a short incubation period, affected individuals develop nausea, vomiting, watery diarrhea, and abdominal pain.
Biopsy morphology is nonspecific. When detected, abnormalities are most evident in the small intestine and include mild villous shortening, epithelial vacuolization, loss of the microvillus brush border, crypt hypertrophy, and lamina propria infiltration by lymphocytes (
Fig. 17-31A ). The disease is self-limited.
Norovirus
This encapsulated virus with a segmented double-stranded RNA genome infects 140 million people and causes 1 million deaths each year, making rotavirus the most common cause of severe childhood diarrhea and diarrheal mortality worldwide. Children between 6 and 24 months of age are most vulnerable.
Protection in the first 6 months of life is probably due to the presence of antibodies to rotavirus in breast milk, while protection beyond 2 years is due to immunity that develops following the first infection. [88] Outbreaks in hospitals and daycare centers are common, and infection spreads easily; the estimated minimal infective inoculum is
only 10 viral particles.
It selectively infects and destroys mature enterocytes in the small intestine, and the villus surface is repopulated by immature secretory cells. This results in loss of absorptive function and net secretion of water and electrolytes that is compounded by an osmotic diarrhea from incompletely absorbed nutrients. Like norovirus, rotavirus this has short incubation period followed by several days of vomiting and watery diarrhea.
Rotavirus.
The second most common cause of pediatric diarrhea (after rotavirus), _______ also affectsimmunocompromised patients. [89]
Small intestinal biopsy specimens can show epithelial degeneration but more often exhibit nonspecific villous atrophy and compensatory crypt hyperplasia. Viral nuclear inclusions are uncommon. Disease typically presents after an incubation period of 1 week with nonspecific symptoms that include diarrhea, vomiting, and
abdominal pain. Fever and weight loss may also be present. Symptoms generally resolve within 10 days.
adenovirus
It is characterized by chronic, relapsing abdominal pain, bloating,
and changes in bowel habits. Despite very real symptoms, the gross and microscopicevaluation is normal in most IBS patients. Thus, the diagnosis depends on clinical symptoms.
Irritable Bowel Disease
Explain the pathophysio of IBS
The pathogenesis of IBS remains poorly defined, although there is clearly an interplay between* psychologic stressors, diet, and abnormal GI motility*. Data showing **disturbances of intestinal motility and enteric sensory function suggest that impairment of signaling in the brain-gut axis **contributes to IBS. A small subgroup of IBS patients also relate onset to a bout of infectious gastroenteritis, suggesting an immune or neuroimmune contribution.
This is a chronic condition resulting from inappropriate mucosal
immune activation.
Inflammatory Bowel Disease ( IBD )
The two disorders that comprise IBD are :
Crohn’s disease
ulcerative colitis
The distinction between ulcerative colitis and Crohn disease is based, in large part, on the _________.
distribution of affected sites
morphologic expression of disease
STUDY( Table17-8 ) at those sites.
crohn’s disease
Ulcerative Colitis
Croh’s disease
Ulcerative Colitis
Crohn’s disease
Ulcerative Colitis
Molecular linkage analyses of affected families have identified _______ as a susceptibility gene in Crohn disease.
This encodes a protein that binds to intracellular bacterial peptidoglycans and subsequently activates NF-κB. It has been postulated that
this variants are less effective at recognizing and combating
luminal microbes, which are then able to enter the lamina propria and trigger
inflammatory reactions. Other data suggest that it may regulate immune responses
to prevent excessive activation by luminal microbes. Whatever the mechanism by which thiscontribute to Crohn disease pathogenesis, it should be
remembered that fewer than 10% of individuals carrying this mutations develop
disease.
NOD2
Crohn disease may occur in any area of the GI tract, but the most common
sites involved at presentation are the __________.
Disease is limited to the small intestine alone in about 40% of cases; the small intestine and colon are both involved in 30% of patients; and the remainder have only colonic
involvement. The presence of multiple, separate, sharply delineated areas of disease,
resulting in skip lesions, is characteristic of Crohn disease and may help in the
differentiation from ulcerative colitis. Strictures are common ( Fig. 17-34A )
terminal ileum, ileocecal valve, and cecum
The earliest Crohn disease lesion, the ______, may progress, and multiple lesions
often coalesce into elongated, serpentine ulcers oriented along the axis of the bowel.Edema and loss of the normal mucosal texture are common.
aphthous ulcer
The earliest Crohn disease lesion, the _______, may progress, and multiple lesions often coalesce into elongated, serpentine ulcers oriented along the axis of the bowel. Edema and loss of the normal mucosal texture are common.
aphthous ulc
This is most common in the colon but may occur in the esophagus, stomach, or small
intestine. Most, if not all, begin as small elevations of the mucosa. These are referred to as sessile, a term borrowed from botanists who use it to describe flowers and leaves that grow directly from the stem without a stalk.
polyps
The most common neoplastic polyp is the______, which has the potential to progress to cancer.
adenoma
The nonneoplastic polyps can be further classified as __inflammatory, hamartomatous, or hyperplastic________________.
inflammatory, hamartomatous, or hyperplastic
The polyp that forms as part of the solitary rectal ulcer syndrome is an example of a purely type of this. Patients present with a clinical triad of rectal bleeding, mucus discharge,and an inflammatory lesion of the anterior rectal wall. The underlying cause is impaired relaxation of the anorectal sphincter that creates a sharp angle at the anterior rectal shelf and leads to recurrent abrasion and ulceration of the overlying rectal mucosa.This may ultimately form as a result of chronic cycles of injury and healing. Entrapment of this polyp in the fecal stream leads to mucosal prolapse. Thus, the distinctive histologic features are those of a typical with superimposed mucosal prolapse and include lamina propria fibromuscular hyperplasia, mixed inflammatory infiltrates, erosion, and epithelial hyperplasia
Inflammatory polyp
Solitary rectal ulcer syndrome.
A, The dilated glands, proliferative
epithelium, superficial erosions, and inflammatory infiltrate are typical of an ________
However, the smooth muscle hyperplasia within the lamina propria suggests that mucosalprolapse has also occurred.
B, Epithelial hyperplasia.
C, Granulation tissue-like capillary
proliferation within the lamina propria caused by repeated erosion and re-epithelialization
inflamatory polyp.
This occurs sporadically and in the context of various genetically determined
or acquired syndromes ( Table 17-9 ). Recall that these are tumor-like growths
composed of mature tissues that are normally present at the site in which they develop.
Although these syndromes are rare, they are important to recognize
because of associated intestinal and extra-intestinal manifestations and the possibility that other family members are affected
HAMARTOMATOUS POLYPS
Mean Age at Presentation (yr)— <5
Mutated Gene : SMAD4, BMPR1A
Gastrointestinal Lesions : Juvenile polyps; risk of gastric, small intestinal,colonic, and pancreatic adenocarcinoma
Selected Extra-Gastrointestinal Manifestations: Pulmonary
arteriovenous
malformations, digital clubbing
Juvenile polyposis
Mean Age at Presentation (yr) :10–15
Mutated Gene :LKB1/STK11
Gastrointestinal Lesions : Arborizing polyps; Small intestine > colon > stomach; colonic adenocarcinoma
Selected Extra- Gastrointestinal Manifestations : Skin macules; increased
risk of thyroid, breast, lung, pancreas, gonadal, and bladder cancers
Peutz-Jeghers
syndrome
Mean Age atPresentation (yr) :
Mutated Gene :
Gastrointestinal Lesions :
Selected Extra- Gastrointestinal Manifestations :
Cowden syndrome,
Bannayan- Ruvalcaba-Riley syndrome
Cronkhite Canada Syndrome
tuberous sclerosis
Classic FAP
Attenuated FAP
Gardner Syndrome
Turcot Syndrome
