The Pathology The Pathology ofof

Intestines IIntestines I

Developmental Developmental anomaliesanomalies

AtresiaAtresia (bowel): complete failure of (bowel): complete failure of development of the intestinal lumen development of the intestinal lumen ((imperforate anusimperforate anus))

StenosisStenosis (bowel): narrowing of the (bowel): narrowing of the intestinal lumenintestinal lumen

DuplicationDuplication (small intestine): well- (small intestine): well-formed saccular-tubular cystic spaces formed saccular-tubular cystic spaces (may or may not communicate with the (may or may not communicate with the lumen).lumen).

OmphaloceleOmphalocele (small intestine): a (small intestine): a membranous sac; herniation.membranous sac; herniation.

MalrotationMalrotation (bowel): malposition of (bowel): malposition of the large intestinal components the large intestinal components (caecum in the left upper quadrant).(caecum in the left upper quadrant).

Meckel diverticulum:Meckel diverticulum: (small intestine) (small intestine) Common; in Common; in iileum;leum; Failure of involution of the Failure of involution of the

omphalomesenteric (vitelline) duct omphalomesenteric (vitelline) duct which which connects the lumen of the developing gut to connects the lumen of the developing gut to the yolk sacthe yolk sac ; ;

Persistent blind-ended tubular protrusion (5-Persistent blind-ended tubular protrusion (5-6 cm long); 6 cm long);

CContains all three layers of the normal bowel ontains all three layers of the normal bowel wall: mucosa, submucosa, and muscularis wall: mucosa, submucosa, and muscularis propriapropria;;

AsymptomaticAsymptomatic Pernicious anemia-like syndromes (bacteriaPernicious anemia-like syndromes (bacteria B B1212

depletion);depletion); Acute appendicitis-like syndrome (Acute appendicitis-like syndrome (heterotopic rests heterotopic rests

of gastric mucosaof gastric mucosa P Peptic ulceratioeptic ulcerationnbleeding).bleeding).

Hirschsprung’s DiseaseHirschsprung’s Disease ((Congenital Congenital MegacolonMegacolon))

Pathogenesis:Pathogenesis: The enteric neuronal plexus develops fromThe enteric neuronal plexus develops from

neural crest cellsneural crest cells which must migrate into the bowel wall which must migrate into the bowel wall during developmentduring development mostly in a cephalad-to-caudad mostly in a cephalad-to-caudad direction. direction.

Congenital megacolonCongenital megacolon, or Hirschsprung’s disease, results , or Hirschsprung’s disease, results when the migration of neural crest cells arrests at some when the migration of neural crest cells arrests at some point before reaching the anus.point before reaching the anus.

Hence a segment remains that lacks both Meissner’s Hence a segment remains that lacks both Meissner’s submucosal and Auerbach’s myenteric plexuses. submucosal and Auerbach’s myenteric plexuses.

Loss of enteric neuronal coordination leads toLoss of enteric neuronal coordination leads to (1)(1) functional obstruction functional obstruction (2) (2) colonic dilatation proximal to the affected segment.colonic dilatation proximal to the affected segment.

OOccurs in approximately 1 out of 5000 to 8000 live ccurs in approximately 1 out of 5000 to 8000 live birthsbirths

M/F : 4/1M/F : 4/1

Hirschsprung’s disease is characterized by the Hirschsprung’s disease is characterized by the absence of absence of ganglion cells, ganglion cells, ganglia, ganglia,

iin the muscle wall and submucosa of the affected n the muscle wall and submucosa of the affected segment. segment.

The The rectum is always affectedrectum is always affected, , (m(most cases involve ost cases involve the rectum and sigmoid onlythe rectum and sigmoid only)), ,

Proximal to the aganglionic segment, the colon Proximal to the aganglionic segment, the colon undergoes undergoes progressive dilatation and hypertrophyprogressive dilatation and hypertrophy. .

With time, the colon may become massively With time, the colon may become massively distended, sometimes achieving a diameter of 15 to distended, sometimes achieving a diameter of 15 to 20 cm (20 cm (megacolonmegacolon))

TThe colonic wall becomes markedly thinned and he colonic wall becomes markedly thinned and may may rupturerupture, usually near the c, usually near the caaecum. ecum.

Mucosal inflammation or shallow Mucosal inflammation or shallow stercoral ulcersstercoral ulcers produced by impactedproduced by impacted feces may appear.feces may appear.

Enterocolitis.Enterocolitis.

Acquired megacolonAcquired megacolon

(1) (1) Chagas’ diseaseChagas’ disease (in which the (in which the trypanosomes directly invade the bowel wall trypanosomes directly invade the bowel wall to destroy the enteric plexusesto destroy the enteric plexuses)); ;

(2) (2) obstructionobstruction of the bowel as by a of the bowel as by a neoplasm or inflammatory stricture; neoplasm or inflammatory stricture;

(3) (3) toxictoxic megacolon complicating ulcerative megacolon complicating ulcerative colitis or Crohn’s disease colitis or Crohn’s disease

(4) a functional (4) a functional psychosomaticpsychosomatic disorder. disorder.

Vascular disordersVascular disorders

Ischemic Bowel Ischemic Bowel DiseaseDisease Arterial thrombosisArterial thrombosis Arterial Arterial embolismembolism Venous thrombosisVenous thrombosis Nonocclusive ischemiaNonocclusive ischemia Miscellaneous: Miscellaneous: radiation radiation

injury, volvulus, stricture, and injury, volvulus, stricture, and internal or internal or external external herniationherniation..

AngiodysplasiaAngiodysplasia

HemorrhoidsHemorrhoids

Ischemic Bowel DiseaseIschemic Bowel Disease

RRestricted to the small or large estricted to the small or large intestine or may affect both, intestine or may affect both,

Acute occlusionAcute occlusion of one of the three of one of the three major supply trunks of the intestinesmajor supply trunks of the intestines ((celiac and superior and inferior celiac and superior and inferior mesenteric arteriesmesenteric arteries)) infarction.infarction.

Lesions within the end-arteries, Lesions within the end-arteries, which penetrate the gut wall, which penetrate the gut wall, produce small, produce small, focal ischemic focal ischemic lesionslesions..

The severity of injury ranges fromThe severity of injury ranges from (1)(1) transmural infarctiontransmural infarction of the gut, of the gut,

involving all visceral layersinvolving all visceral layers ( (acute acute occlusion of a major arteryocclusion of a major artery)); ;

(2)(2) mural infarctionmural infarction of the mucosa and of the mucosa and submucosasubmucosa;;

(3)(3) mucosal infarctionmucosal infarction (erosions) (erosions), if the , if the lesion extends no deeper than the lesion extends no deeper than the muscularis mucosamuscularis mucosa..

Arterial embolism: Arterial embolism: cardiac vegetations, cardiac vegetations, angiographic procedures,angiographic procedures, aortic aortic thrombothromboembolism.embolism.

Arterial thrombosis: Arterial thrombosis: severe atherosclerosis (severe atherosclerosis (a.a.mesentericmesentericaa), ), systemic vasculitis (systemic vasculitis (polyarteritis polyarteritis

nodosanodosa), ), dissecting aneurysm, dissecting aneurysm, angiographic procedures, angiographic procedures, aortic reconstructive surgery, aortic reconstructive surgery, surgical accidents, surgical accidents, hypercoagulable states, hypercoagulable states, oral contraceptives.oral contraceptives.

Venous thrombosis: Venous thrombosis: hypercoagulable states, hypercoagulable states, oral contraceptives, oral contraceptives, antithrombin III deficiency, antithrombin III deficiency, intraperitoneal sepsis, intraperitoneal sepsis, the postoperative state, the postoperative state, invasive neoplasms (particularly hepatocellular invasive neoplasms (particularly hepatocellular

carcinoma), carcinoma), cirrhosis, cirrhosis, abdominal trauma.abdominal trauma.

Nonocclusive ischemia:Nonocclusive ischemia: cardiac failure, cardiac failure, shock, shock, dehydration, dehydration, vasoconstrictive drugs vasoconstrictive drugs ((digitalis, vasopressindigitalis, vasopressin, ,

cocaine, heroincocaine, heroin).).

Miscellaneous:-Radiation-Volvulus-Stricture-herniation

MorphologyMorphology

Transmural InfarctionTransmural Infarction:: SSudden and total occlusion of mesenteric udden and total occlusion of mesenteric

arterial blood arterial blood intestinal infarctionintestinal infarction. . AArterial or venous occlurterial or venous occlusionsionhemorrhagic hemorrhagic

infarctinfarct,, ischemic injury ischemic injury mucosal necrosis mucosal necrosis 18-24 18-24

h h fibrinous exudate over the serosa fibrinous exudate over the serosa Margins of the infarct:Margins of the infarct:

in arterial occlusions : in arterial occlusions : distincdistinctt (demarcation) (demarcation) in venous occlusions : in venous occlusions : less distincless distinctt

Microscopy: edema, interstitial hemorrhage, Microscopy: edema, interstitial hemorrhage, necrosisnecrosis

(24 (24 h)h)gangrenegangreneperforationperforationperitonitis !!!peritonitis !!!

MMuralural & Mucosal & Mucosal Infarction Infarction:: In In any level of the gut from the stomach to any level of the gut from the stomach to

anusanus lesions may be multifocallesions may be multifocal-scattered -scattered or or

continuouscontinuous--widely distributedwidely distributed (depends on (depends on the level of the arterial narrowing),the level of the arterial narrowing),

does not affect the entire thickness (may does not affect the entire thickness (may not be visible from the serosal surface),not be visible from the serosal surface),

oon opening the bowel, there is hemorrhagic, n opening the bowel, there is hemorrhagic, edematous thickening of the mucosaedematous thickening of the mucosa..

Superficial ulcerations withSuperficial ulcerations with edema, edema, hemorrhage, hemorrhage, fibrinous inflammation (psedomembrane due fibrinous inflammation (psedomembrane due

to superinfection).to superinfection).

Chronic IschemiaChronic Ischemia:: CChronic vascular insufficiency hronic vascular insufficiency mucosal mucosal

inflammation and ulceration inflammation and ulceration Submucosal chronic inflammation and Submucosal chronic inflammation and

fibrosis fibrosis stricture stricture.. SSegmental and patchy.egmental and patchy.

AngiodysplasiaAngiodysplasia

Tortuous dilatations of submucosal Tortuous dilatations of submucosal and mucosal blood vessels and mucosal blood vessels

most often in the cecum or right most often in the cecum or right coloncolon

after the sixth decade of lifeafter the sixth decade of life intestinal bleedingintestinal bleeding::

chronic and intermittent chronic and intermittent ((anemia)anemia) acute and massiveacute and massive..

HemorrhoidsHemorrhoids

VVariceal dilatations of the anal and ariceal dilatations of the anal and perianal venous plexusesperianal venous plexuses

Persitently elevated venous pressure Persitently elevated venous pressure within the hemorrhoidal plexuswithin the hemorrhoidal plexus

Predispositions: Predispositions: chronic constipation, chronic constipation, pregnancy.pregnancy.

Thin-walled, dilated vesselsThin-walled, dilated vessels Complications: Bleeding, prolapsing.Complications: Bleeding, prolapsing.

Diarrheal diseasesDiarrheal diseases

DiarrheaDiarrhea is an increase in stool: is an increase in stool: MassMass FrequencyFrequency FludityFludity

DisenteryDisentery is a kind of diarrhea with: is a kind of diarrhea with: Low-volumeLow-volume PainPain HemorrhageHemorrhage

DiarrheaDiarrhea

1. Secretory diarrhea1. Secretory diarrhea 2. Osmotic diarrhea2. Osmotic diarrhea 3. Exudative diarrhea3. Exudative diarrhea 4. Malabsorption4. Malabsorption 5. Deranged motility5. Deranged motility

1. Secretory diarrhea1. Secretory diarrhea

Intestinal fluid secretion (catarrh)Intestinal fluid secretion (catarrh) SerousSerous Causes:Causes:

Infection (bacteria, virus)Infection (bacteria, virus) Neoplastic (secretion of peptides and Neoplastic (secretion of peptides and

serotonin)serotonin) Excessice laxative use Excessice laxative use

2. Osmotic diarrhea2. Osmotic diarrhea

Excessive osmotic forcesExcessive osmotic forces Causes:Causes:

Lactulose therapy (hepatic Lactulose therapy (hepatic encephalopathy, constipation)encephalopathy, constipation)

Gut lavageGut lavage Antacids (magnesium salts)Antacids (magnesium salts)

3. Exudative diarrhea3. Exudative diarrhea

Purulent/bloody stoolPurulent/bloody stool Causes:Causes:

Infections Infections escherichia, escherichia, campylobacter, campylobacter, shigella, shigella, salmonella,salmonella, Entamoeba histolytica, Entamoeba histolytica,

Idiopathic inflammatory bowel diseaseIdiopathic inflammatory bowel disease

4. Malabsorption4. Malabsorption

Voluminous, bulky stoolVoluminous, bulky stool Causes:Causes:

Defective intraluminal digestionDefective intraluminal digestion Defective mucosal cell absorptionDefective mucosal cell absorption Reduced small intestinal surface areaReduced small intestinal surface area Lymphatic obstructionLymphatic obstruction Infection (Infection (GiardiaGiardia))

5. Deranged motility5. Deranged motility

Decreased intestinal retention timeDecreased intestinal retention time Surgical reduction of gut lengthSurgical reduction of gut length Neural dysfunction (irritable bowel Neural dysfunction (irritable bowel

syndrome)syndrome) HyperthyroidismHyperthyroidism

Decreased motilityDecreased motility SurgerySurgery Bacterial overgrowth in the small Bacterial overgrowth in the small

intestineintestine

Infectious enterocolitisInfectious enterocolitis

Intestinal diseases of microbial origin Intestinal diseases of microbial origin DDiarrhea and sometimes iarrhea and sometimes

ulceroinflammatory changesulceroinflammatory changes MMost common offenders ost common offenders

rotavirus rotavirus Norwalk virus Norwalk virus EEnterotoxigenic nterotoxigenic Escherichia coliEscherichia coli

OOffenders vary with the ffenders vary with the age, age, nutrition, nutrition, immune status of the host, immune status of the host, environment (living conditions, public environment (living conditions, public

health measures), health measures), SSpecial predispositionspecial predispositions::

hospitalization, hospitalization, wartime dislocation, wartime dislocation, foreign travelforeign travel..

Viral GastroenterocolitisViral Gastroenterocolitis

TThe small intestinal mucosa usually he small intestinal mucosa usually exhibitsexhibits sshortened villi hortened villi infiltration of the lamina propria by infiltration of the lamina propria by

lymphocytes lymphocytes vvacuolization and loss of the microvillus acuolization and loss of the microvillus

brush border in surface epithelial cells brush border in surface epithelial cells crypts appear hypertrophied crypts appear hypertrophied vviral particles within surface epithelial iral particles within surface epithelial

cells by electron microscopy and in stool. cells by electron microscopy and in stool.

BacteriBacterial Gastroenterocolitisal Gastroenterocolitis

NNumerous bacteria and several pathogenic umerous bacteria and several pathogenic mechanismsmechanisms:: Ingestion of preformed toxin, present in Ingestion of preformed toxin, present in

contaminated foodcontaminated food (m (major offenders are ajor offenders are Staphylococcus aureus,Staphylococcus aureus, Vibrios, and Vibrios, and Clostridium Clostridium perfringensperfringens))

Infection by toxigenic organismsInfection by toxigenic organisms ( (which which proliferate within the gut lumen and elaborate an proliferate within the gut lumen and elaborate an enterotoxinenterotoxin))

Infection by enteroinvasive organismsInfection by enteroinvasive organisms ( (which which proliferate, invade, and destroy mucosal epithelial proliferate, invade, and destroy mucosal epithelial cellscells))

Most bacterial infections exhibit a Most bacterial infections exhibit a general nonspecific pattern: general nonspecific pattern: damage of the surface epitheliumdamage of the surface epithelium decreased epithelial cell maturation decreased epithelial cell maturation an increased mitotic rate an increased mitotic rate

(“regenerative change”) (“regenerative change”) hyperemia and edema of the lamina hyperemia and edema of the lamina

propria propria variable neutrophilic infiltration into variable neutrophilic infiltration into

the lamina propria and epithelial layer.the lamina propria and epithelial layer.

Salmonella (multiple species, including Salmonella (multiple species, including S. S. typhimurium typhimurium and and S. paratyphi):S. paratyphi): primarily ileum and colonprimarily ileum and colon blunted villi, blunted villi, vascular congestion, vascular congestion, Peyer’s patch involvement with swelling, Peyer’s patch involvement with swelling, congestion, congestion, ulceration ulceration ((linear ulcerslinear ulcers))

TTyphoid feveryphoid fever : : may result in chronic may result in chronic infection of infection of biliary tree, biliary tree, joints, joints, bones, bones, mmeningeseninges..

ShigellaShigella primarily distal colon primarily distal colon acute mucosal inflammation and erosion acute mucosal inflammation and erosion purulent exudate purulent exudate 

CampylobacterCampylobacter small intestine, appendix, colon small intestine, appendix, colon villus blunting villus blunting multiple superficial ulcers multiple superficial ulcers mucosal inflammation mucosal inflammation purulent exudatepurulent exudate

Yersinia enterocoliticaYersinia enterocolitica and and Y. Y. pseudotuberculosis:pseudotuberculosis: ileum, appendix, and colonileum, appendix, and colon mucosal hemorrhage and ulceration mucosal hemorrhage and ulceration bowel wall thickening bowel wall thickening Peyer’s patch and mesenteric lymph node Peyer’s patch and mesenteric lymph node

hypertrophy with necrotizing granulomas hypertrophy with necrotizing granulomas systemic spread systemic spread ((with peritonitis, pharyngitis, with peritonitis, pharyngitis,

pericarditispericarditis 3-Ps) 3-Ps) V. cholerae:V. cholerae:

essentially intact small intestinal mucosa, essentially intact small intestinal mucosa, with mucus-depleted cryptswith mucus-depleted crypts

C. perfringens: C. perfringens: similar to similar to V. choleraeV. cholerae but with some epithelial but with some epithelial

damage; damage; some strains produce a severe necrotizing some strains produce a severe necrotizing

enterocolitis with perforationenterocolitis with perforation..

Necrotizing EnterocolitisNecrotizing Enterocolitis

NeonatesNeonates ( (premature or of low birth premature or of low birth weightweight))

acute, necrotizing inflammationacute, necrotizing inflammation.. A A combination of combination of

ischemic injury, ischemic injury, colonization by pathogenic organisms, colonization by pathogenic organisms, excess protein substrate in the intestinal excess protein substrate in the intestinal

lumen,lumen, functional immaturity of the neonatal gut.functional immaturity of the neonatal gut.

The disease may present as a The disease may present as a mildmild gastrointestinal disturbance or as a gastrointestinal disturbance or as a fulminantfulminant illness with illness with intestinal gangrene, intestinal gangrene, perforation, perforation, sepsis, sepsis, shock. shock.

TTerminal ileum and ascending colon, erminal ileum and ascending colon, although in severe cases, the entire although in severe cases, the entire

small and large bowel may be involved. small and large bowel may be involved.

In early phases, the mucosa exhibits In early phases, the mucosa exhibits edema, edema, hemorrhage, hemorrhage, necrosisnecrosis

As the disease progresses, the full As the disease progresses, the full thickness of the bowel wall becomes thickness of the bowel wall becomes hemorrhagic, hemorrhagic, inflamed, inflamed, gangrenous gangrenous frank intraluminal hemorrhage frank intraluminal hemorrhage mural gas formation mural gas formation

Reparative changeReparative changess epithelial regeneration epithelial regeneration granulation tissue formationgranulation tissue formation ffibrosisibrosis..

Antibiotic-Associated Colitis Antibiotic-Associated Colitis (Pseudomembranous Colitis(Pseudomembranous Colitis))

C. difficileC. difficile ( (a normal gut commensala normal gut commensal)) acute colitisacute colitis plaque-like adhesion of plaque-like adhesion of

fibrinopurulent-necrotic debris and fibrinopurulent-necrotic debris and mucus to damaged colonic mucosamucus to damaged colonic mucosa

following a course of broad-following a course of broad-spectrum antibiotic therapyspectrum antibiotic therapy

alsoalso may occur following any severe may occur following any severe mucosal injury, mucosal injury, iischemic colitis, schemic colitis, volvulus, volvulus, necrotizing infections (staphylococci, necrotizing infections (staphylococci,

shigella, candida, necrotizing shigella, candida, necrotizing enterocolitis)enterocolitis)

Malabsorption Malabsorption SyndromesSyndromes

Malabsorption is characterized by Malabsorption is characterized by suboptimal absorption of fats, fat-suboptimal absorption of fats, fat-soluble and other vitamins, proteins, soluble and other vitamins, proteins, carbohydrates, electrolytes and carbohydrates, electrolytes and minerals, and water.minerals, and water.

The consequences of malabsorption The consequences of malabsorption affect many organ systemsaffect many organ systems..

EtiologyEtiology MMal-digestional-digestion::

EExocrine pancreatic xocrine pancreatic diseasedisease

Lack of bile salts Lack of bile salts Disaccharidase Disaccharidase

(lactase, etc.) (lactase, etc.) deficiency deficiency

Problems with the small Problems with the small bowel mucosabowel mucosa:: SprueSprue Crohn's Crohn's diseasedisease Whipple'sWhipple's disease disease Acute infections Acute infections ParasitesParasites (Giardia) (Giardia) Allergic gastroenteritisAllergic gastroenteritis Amyloidosis Amyloidosis Lymphomas Lymphomas Radiation sickness / Radiation sickness /

BB1212 / folate deficiency / folate deficiency

Super-fast transit timeSuper-fast transit time:: Laxatives Laxatives Cholera Cholera Vasoactive intestinal Vasoactive intestinal

polypeptide-producing polypeptide-producing tumorstumors

Mechanical problemsMechanical problems:: Blocked lymphatics Blocked lymphatics

(cancer, TB) (cancer, TB) After re-routing surgery After re-routing surgery

(gastrectomy, bypass)(gastrectomy, bypass)

ClinicopathologyClinicopathology Alimentary tract:Alimentary tract:

ddiarrheaiarrhea abdominal pain abdominal pain weight lossweight loss vitamin deficienciesvitamin deficiencies

Hematopoietic Hematopoietic system:system: anemia anemia ((iron, iron,

pyridoxine, folate, or pyridoxine, folate, or vitamin B12 deficiencyvitamin B12 deficiency))

bleeding bleeding ((vitamin K vitamin K deficiencydeficiency))

Nervous system: Nervous system: peripheral neuropathyperipheral neuropathy

Skin:Skin: purpura and purpura and

petechiaepetechiae edema edema dermatitisdermatitis hyperkeratosis hyperkeratosis

Musculoskeletal Musculoskeletal system:system: osteoposteoporosisorosis ttetany etany

Endocrine system: Endocrine system: amenorrhea amenorrhea impotence impotence infertility infertility hyperparathyroidishyperparathyroidismm

Celiac sprueCeliac sprue

Small intestineSmall intestine iidiosyncratic reaction to diosyncratic reaction to gliadingliadin, a , a

protein in the gluten of wheat, rye, and protein in the gluten of wheat, rye, and barleybarley

aan n antibodyantibody against the against the transglutaminasetransglutaminase

activated cytotoxic killer-T cells invade activated cytotoxic killer-T cells invade the epitheliumthe epithelium

Microscopy:Microscopy: vvilli disappearilli disappear crypts deepencrypts deepen

Whipple'sWhipple's diseasedisease

Small intestine & systemicSmall intestine & systemic lipid pools in the mucosalipid pools in the mucosa Tropheryma whippeliiTropheryma whippelii

(~(~actinomycesactinomyces)) bbacilli-laden macrophagesacilli-laden macrophages

in:in: gut mucosagut mucosa lymph nodes, lymph nodes, joints, joints, endocardium endocardium bbrainrain..

IDIOPATHIC IDIOPATHIC INFLAMMATORY BOWEL INFLAMMATORY BOWEL

DISEASESDISEASES

Crohn’s DiseaseCrohn’s Disease IdiopathicIdiopathic Western developed Western developed

populationspopulations limited to the terminal limited to the terminal

ileumileum (terminal ileitis)(terminal ileitis) segmental lesionssegmental lesions

with intervening with intervening unaffected (“skip”) unaffected (“skip”) areasareas ((regional regional enteritisenteritis))

any level of the any level of the alimentary tractalimentary tract with with systemic systemic manifestationsmanifestations

EEarly diseasearly disease: : focal mucosal ulcersfocal mucosal ulcers

PProgressive diseaserogressive disease:: mucosal ulcers mucosal ulcers

coalescecoalescelong, long, serpentine serpentine “linear “linear ulcers”ulcers”

tend to be oriented tend to be oriented along the axis of the along the axis of the bowelbowel

mucosa acquires a mucosa acquires a coarsely textured, coarsely textured, “cobblestone” “cobblestone” appearance appearance

nnarrow fissuresarrow fissures penetrating deeply penetrating deeply through the bowel through the bowel wallwall

perforation or perforation or localized abscesseslocalized abscesses

Hallmark:Hallmark: sharp sharp demarcation of demarcation of diseased bowel diseased bowel segments from segments from adjacent adjacent uninvolved uninvolved bowel.bowel.

Crohn’s disease: Crohn’s disease: MorphologyMorphology

SerosaSerosa:: granular and granular and dull graydull gray

Mesentery:Mesentery: thickened, thickened, edematous, and edematous, and sometimes fibroticsometimes fibrotic

IIntestinal wallntestinal wall:: rubbery rubbery and thickand thick ( (edema, edema, inflammation, fibrosis, inflammation, fibrosis, hypertrophy of the hypertrophy of the muscularismuscularis))

Lumen:Lumen: narrowednarrowed ( (x-ray x-ray film film of of small intestinesmall intestine showsshows “string sign” “string sign” ))

Segmental disease:Segmental disease: sharp demarcation of sharp demarcation of diseased bowel diseased bowel segments from adjacent segments from adjacent uninvolved boweluninvolved bowel..

Crohn’s disease: MorphologyCrohn’s disease: Morphology

Crohn’s disease: Crohn’s disease: MorphologyMorphology

Microscopic Characteristics:Microscopic Characteristics: TTransmural involvement of the bowel byransmural involvement of the bowel by

inflammatory processinflammatory process mucosal damage mucosal damage nnoncaseating granulomasoncaseating granulomas(50%)(50%) llymphoid aggregatesymphoid aggregates fibrosisfibrosisstricturesstrictures

FFissuring and formation of fistulasissuring and formation of fistulas Crypt destructionCrypt destruction

progressive atrophyprogressive atrophy Paneth cellPaneth cell metaplasia metaplasia

Ulcerative colitisUlcerative colitis AAn ulceroinflammatory n ulceroinflammatory

disease disease limited to the colon limited to the colon affecting only the affecting only the

mucosa and mucosa and submucosasubmucosa

extends in a extends in a continuous fashion continuous fashion proximally from the proximally from the rectum rectum (i(in contrast to n contrast to CCrohn’s disease)rohn’s disease)

granulomas are absentgranulomas are absent

Systemic disorderSystemic disorder (similar (similar to Cto Crohn’s rohn’s disease) disease) migratory migratory

polyarthritis, polyarthritis, sacroiliitis, sacroiliitis, aannkylosing kylosing

spondylitis, spondylitis, uveitis, uveitis, hepatic involvement hepatic involvement

(pericholangitis and (pericholangitis and primary sclerosing primary sclerosing cholangitis), cholangitis),

skin lesions.skin lesions.

IInvolves the rectum nvolves the rectum and extends and extends proximally in a proximally in a retrograde fashion retrograde fashion to involve the to involve the entire colon entire colon (“pancolitis”) in the (“pancolitis”) in the more severe cases. more severe cases.

It is a disease of It is a disease of continuity continuity ““skip” lesions such skip” lesions such

as occur in CD are as occur in CD are not found not found

In 10% of patients In 10% of patients with severe with severe pancolitis, the distal pancolitis, the distal ileum may develop ileum may develop mild mucosal mild mucosal inflammation inflammation (“backwash ileitis”). (“backwash ileitis”).

The appendix may The appendix may be involved with be involved with both CD and UC.both CD and UC.

TThe mucosa exhibithe mucosa exhibitss slight reddening slight reddening granularity granularity friability friability easy bleeding easy bleeding

FFully developed ully developed severe, active severe, active inflammationinflammation:: extensive and broad-extensive and broad-

based ulceration of based ulceration of the mucosa in the the mucosa in the distal colon or distal colon or throughout its length throughout its length

Isolated islands of Isolated islands of regenerating mucosa regenerating mucosa bulge upward to bulge upward to create create “pseudopolyps.” “pseudopolyps.”

Often the Often the undermined edges of undermined edges of adjacent ulcers adjacent ulcers interconnect to interconnect to create tunnels create tunnels covered by tenuous covered by tenuous mucosal bridges. mucosal bridges.

TThe ulcers are he ulcers are frequently aligned along frequently aligned along the axis of the colonthe axis of the colon (a (as s with CDwith CD))

IIn contrast to Cn contrast to Crohn’s rohn’s disease:disease: rarely do the linear rarely do the linear

serpentine ulcersserpentine ulcers mural thickening does not mural thickening does not

occuroccur PProgressive mucosal rogressive mucosal

atrophy atrophy in chronic casesin chronic cases

Microscopy:Microscopy: diffuse mononuclear diffuse mononuclear

inflammatory infiltrate in inflammatory infiltrate in the lamina propria, the lamina propria, admixed with admixed with

neutrophils neutrophils occasional eosinophils and occasional eosinophils and

mast cellsmast cells..

Diffuse mononuclear cell infitration

Pseudopolyps (carpet-like mucosa)

ulcer

pseudopolyp

Crypt abscess

Crypt abscess

LLong-term ong-term complication of UC complication of UC : : cancer.cancer.

ParticularParticular attention attention to:to: epithelial changes epithelial changes

signifying dysplasia signifying dysplasia andand

the progression to the progression to frank carcinomafrank carcinoma

UUnderlying nderlying inflammatory inflammatory disease may mask disease may mask the symptoms and the symptoms and signs of carcinomasigns of carcinoma

TThe risk of he risk of cancercancer is highest is highest in patients with in patients with pancolitis of 10 or pancolitis of 10 or more years’ more years’ duration, in whom duration, in whom it exceeds by 20-it exceeds by 20-fold to 30-fold fold to 30-fold that in a control that in a control populationpopulation..

Celiac sprueCeliac sprue Gluten (gladin)Gluten (gladin) Small intestineSmall intestine villi disappearvilli disappear

crypts deepencrypts deepen

Whipple'sWhipple's diseasedisease Tropherhyma Tropherhyma

whippliwhippliii Small intestineSmall intestine((lymph nodes, joints, lymph nodes, joints, endocardium and/or endocardium and/or brainbrain))

bbacilli-laden macrophages acilli-laden macrophages

Bacterial Bacterial Overgrowth Overgrowth SyndromeSyndrome

AAerobic and erobic and anaerobic anaerobic organisms organisms

PProximal small roximal small

bowelbowel luminal stasisluminal stasis, , hypochlorhydrihypochlorhydria, a,

immunedeficiencies immunedeficiencies Disaccharidase Disaccharidase deficiencydeficiency

Less Less intestinal intestinal lactase lactase

Small intestineSmall intestineosmotic diarrheaosmotic diarrhea

AbetalipoAbetalipo--proteinemiaproteinemia

Inability to Inability to

synthesizesynthesize AllAll enterocytes loaded with enterocytes loaded with

dietary fat dietary fat

Crohn’s DiseaseCrohn’s Disease IdiopathicIdiopathic TTerminal ileerminal ileumum noncaseating noncaseating granulomasgranulomas and ulcers and ulcers

with perforationwith perforation Ulcerative Ulcerative

ColitisColitis IdiopathicIdiopathic ColonColon SSevereevere active active

inflammationinflammation, ulcers & , ulcers & pseudopolypspseudopolyps

Malabsorption Syndromes

LocationLocation BowelBowel Terminal ileumTerminal ileum ColonColon Anal troublesAnal troubles Oral lesionsOral lesions Skip lesionsSkip lesions LayersLayers UlcersUlcers PseudopolypsPseudopolyps FibrosisFibrosis FistulasFistulas GranulomasGranulomas BleedingBleeding Carcinoma riskCarcinoma risk

Crohn's diseaseCrohn's diseaseVariableVariable

SmallSmallFavorite siteFavorite site

Right more than leftRight more than leftCommonCommonMaybeMaybe

++All threeAll three

Linear fissuresLinear fissures++++++++++++

++++

SubtleSubtle++

Ulcerative colitisUlcerative colitisRectum and upwardsRectum and upwards

LargeLarge"Backwash""Backwash"

Left more than rightLeft more than right----

No; continuousNo; continuousMucosa onlyMucosa only

Broad / irregularBroad / irregular++++------

Heavy-dutyHeavy-duty++++++

Colonic Diverticulosis Colonic Diverticulosis

A A diverticulumdiverticulum is a is a blind pouch leading off blind pouch leading off the alimentary tract, the alimentary tract, lined by mucosa that lined by mucosa that communicates with the communicates with the lumen of the gutlumen of the gut

Acquired diverticula may Acquired diverticula may occur in the esophagusoccur in the esophagus, , stomach, and stomach, and duodenum; duodenal duodenum; duodenal diverticula occur in more diverticula occur in more than 1% of adults than 1% of adults

Congenital Congenital diverticuladiverticula ((Meckel’s Meckel’s diverticulumdiverticulum)) have have all three layers of all three layers of the bowel wall; the bowel wall;

all other diverticula all other diverticula are acquired and are acquired and either lack or have either lack or have an attenuated an attenuated muscularis propria. muscularis propria.

Most colonic Most colonic diverticula are small diverticula are small flask-like or spherical flask-like or spherical outpouchings, outpouchings, usually 0.5 to 1 cm in usually 0.5 to 1 cm in diameter and located diameter and located in the sigmoid colonin the sigmoid colon descending colon or descending colon or

entire colon, however, entire colon, however, may be affectedmay be affected

PathogenesisPathogenesis (1) focal weakness in (1) focal weakness in

the colonic wall the colonic wall (2) increased (2) increased

intraluminal pressure.intraluminal pressure.

HistologHistology:y: a thin wall a thin wall

composed of a composed of a flattened or atrophic flattened or atrophic mucosa, mucosa,

compressed compressed submucosa, submucosa,

attenuated or attenuated or totally absent totally absent muscularis propria muscularis propria

hhypertrophy of the ypertrophy of the circular layer of the circular layer of the muscularis propria muscularis propria in the affected in the affected bowel segment is bowel segment is usually seen.usually seen.

ComplicationsComplications

Obstruction Obstruction PPerforationerforation MMarked fibrotic arked fibrotic

thickeningthickening due to due to the ithe inflammationnflammation

NNarrowing arrowing ((resembleresembless colonic colonic cancercancer))

DDiverticular iverticular infection infection pericolic abscesses pericolic abscesses sinus tractssinus tracts pelvic or pelvic or

generalized generalized peritonitis.peritonitis.

Mechanical obstructionMechanical obstruction Adhesions Adhesions ((post-op, Crohn's) post-op, Crohn's) HerniasHernias VolvulusVolvulus IntussusceptionIntussusception TumorsTumors Inflammatory stricturesInflammatory strictures Obstructive material (gallstone, Obstructive material (gallstone,

fecalith, foreign body)fecalith, foreign body) CongenitalCongenital

Atresia of the anus / imperforate Atresia of the anus / imperforate anus anus

Congenital atresia / strictures Congenital atresia / strictures Meconium ileus (cystic fibrosis)Meconium ileus (cystic fibrosis)

Pseudo-obstructionPseudo-obstruction Paralytic ileusParalytic ileus Vascular bowel infarctionVascular bowel infarction Myopathies & neuropathies Myopathies & neuropathies

(Hirschsprung’s disease(Hirschsprung’s disease))

Bowel ObstructionBowel Obstruction

Bowel Obstruction : HerniasBowel Obstruction : Hernias

A weakness or defect in A weakness or defect in the wall of the peritoneal the wall of the peritoneal cavity may permit cavity may permit protrusion of a pouch-protrusion of a pouch-like, serosa-lined sac of like, serosa-lined sac of peritoneum, called a peritoneum, called a hernial sac. hernial sac.

The usual sitesThe usual sites:: anteriorly at the inguinal anteriorly at the inguinal

and femoral canals, and femoral canals, umbilicus, umbilicus, surgical scars. surgical scars.

IIntruders ntruders :: small bowel loops, small bowel loops, oomentummentum,, large bowellarge bowel..

Pathology:Pathology: impair venous impair venous

drainage of the drainage of the trapped viscus trapped viscus

stasis and edema stasis and edema compromise of arterial compromise of arterial

supply and venous supply and venous drainage drainage (strangulation) (strangulation)

infarction of the infarction of the trapped segment.trapped segment.

Bowel Obstruction : AdhesionsBowel Obstruction : Adhesions

Peritonitis:Peritonitis: ssurgical procedures, urgical procedures, infection, infection, eendometriosisndometriosis..

As the peritonitis healsAs the peritonitis heals:: adhesions adhesions ((between between

bowel segments or the bowel segments or the abdominal wall and abdominal wall and operative siteoperative site))

fibrous bridges fibrous bridges closed closed loops loops trapped trapped intestineintestine (internal (internal herniation). herniation).

The sequence of The sequence of events following events following herniationherniation:: obstruction obstruction sstrangulationtrangulation..

Bowel Obstruction : IntussusceptionBowel Obstruction : Intussusception Intussusception Intussusception

occurs when one occurs when one segment of the small segment of the small intestine, constricted intestine, constricted by a wave of by a wave of peristalsis, suddenly peristalsis, suddenly becomes telescoped becomes telescoped into the immediately into the immediately distal segment of distal segment of bowel.bowel. Once trapped, the Once trapped, the

invaginated segment invaginated segment is propelled by is propelled by peristalsis farther into peristalsis farther into the distal segment, the distal segment, pulling its mesentery pulling its mesentery along behind italong behind it..

Clinical:Clinical: intraluminal mass intraluminal mass

or tumor as the or tumor as the point of traction. point of traction.

Complications: Complications: intestinal intestinal

obstruction obstruction infarction.infarction.

Bowel Obstruction : VolvulusBowel Obstruction : Volvulus

Complete twisting of Complete twisting of a loop of bowel a loop of bowel about its mesenteric about its mesenteric base of attachment base of attachment

produces intestinal produces intestinal obstruction and obstruction and infarction. infarction.

SSigmoid, igmoid, cecum, cecum, small bowel (all or small bowel (all or

portions), portions), stomach, stomach, transverse colon transverse colon

(rarely). (rarely).