This document summarizes inflammatory bowel disease (IBD), specifically ulcerative colitis and Crohn's disease. IBD results from an abnormal immune response in the gastrointestinal tract against gut bacteria and antigens. Ulcerative colitis is limited to inflammation of the colon mucosa, while Crohn's disease can impact any part of the GI tract and causes transmural inflammation. The causes of IBD are unknown but involve genetic susceptibility and environmental triggers like infections. Histologically, ulcerative colitis shows diffuse mucosal inflammation and crypt abscesses, while Crohn's disease features non-caseating granulomas and deep ulcers with fibrosis.

1. Inflammatory bowel diseaseInflammatory bowel disease
Inflammatory bowel disease (IBD) commonly refers toInflammatory bowel disease (IBD) commonly refers to
 Ulcerative colitis (UC)Ulcerative colitis (UC)
 Crohn disease (CD),Crohn disease (CD),
which are chronic inflammatory diseases of the GI tract of unknownwhich are chronic inflammatory diseases of the GI tract of unknown
etiology.etiology.
 CD and UC are chronic relapsing inflammatory disorders whichCD and UC are chronic relapsing inflammatory disorders which
share many common features.share many common features.
 They result from an abnormal local immune response against theThey result from an abnormal local immune response against the
normal flora of the gut, and probably against some self antigensnormal flora of the gut, and probably against some self antigens
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2. CrohnCrohn’’s Diseases Disease
 It is an idiopathicIt is an idiopathic "a disease or condition the cause of which is not "a disease or condition the cause of which is not
known or that arises spontaneously"known or that arises spontaneously", chronic ulcero-constrictive, chronic ulcero-constrictive
inflammatory disease of the alimentary tract from mouth to anus butinflammatory disease of the alimentary tract from mouth to anus but
most commonly affects terminal ileummost commonly affects terminal ileum
 Crohn disease is also referred to as regional enteritis, terminalCrohn disease is also referred to as regional enteritis, terminal
ileitis, or granulomatous ileocolitis.ileitis, or granulomatous ileocolitis.
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3. Ulcerative colitisUlcerative colitis
 Ulcerative colitis is a nongranulomatous disease limited to the colonUlcerative colitis is a nongranulomatous disease limited to the colon
 Whereas UC is confined to the large intestineWhereas UC is confined to the large intestine
 limited to the mucosa and submucosalimited to the mucosa and submucosa
 begins in the rectum and extends proximally in a continuous fashionbegins in the rectum and extends proximally in a continuous fashion
 (almost always involve the rectum)(almost always involve the rectum)
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4. AetiopathogenesisAetiopathogenesis
 Etiology unknownEtiology unknown
 Possibly an exaggerated and destructive mucosal immunePossibly an exaggerated and destructive mucosal immune
response.response.
The tissue injury in IBD is likely to be initiated by -The tissue injury in IBD is likely to be initiated by -
 Genetic susceptibility and failure of immune regulation,Genetic susceptibility and failure of immune regulation,
 that are triggered by environmental influences, including microbesthat are triggered by environmental influences, including microbes
and their products.and their products.
 various types of mycobacteria (particularlyvarious types of mycobacteria (particularly M. paratuberculosisM. paratuberculosis))
 E. coliE. coli
 YersiniaYersinia
 streptococcistreptococci
 viruses (including measles)viruses (including measles)
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5. AetiopathogenesisAetiopathogenesis
 Both the clinical manifestations and the morphologicBoth the clinical manifestations and the morphologic
changes of IBD are ultimatelychanges of IBD are ultimately
 the result of activation of inflammatory cells-neutrophilsthe result of activation of inflammatory cells-neutrophils
initially and mononuclear cells later in the course.initially and mononuclear cells later in the course.
 cause nonspecific tissue injury.cause nonspecific tissue injury.
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6. Pathology : Morpholgy of ChronPathology : Morpholgy of Chron ’’s diseases disease
 Inflammatory infiltrate around the crypts→Inflammatory infiltrate around the crypts→ ulcerationulceration of superficialof superficial
mucosa (Cobble stone ) ⇓mucosa (Cobble stone ) ⇓
 Inflammatory cells invade deeper layers and organize intoInflammatory cells invade deeper layers and organize into non-non-
caseating granulomascaseating granulomas→ deeper ulcers (→ deeper ulcers (Cobblestone patternCobblestone pattern - ulcers- ulcers
criss-crossing each other with surrounding oedema). with,criss-crossing each other with surrounding oedema). with, sinuses/sinuses/
fistulasfistulas formation.formation.
 Thickening of the bowel wallThickening of the bowel wall and narrowing of the lumen → obstruction,and narrowing of the lumen → obstruction,
⇓⇓
 Transmural extensionTransmural extension of inflammatory process →Involvement of serosaof inflammatory process →Involvement of serosa
& mesentry& mesentry
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7.  CobblestoneCobblestone
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8. 88

9. Microscopic examination,Microscopic examination,
 Inflammatory changes throughout the entire thickness of the wallInflammatory changes throughout the entire thickness of the wall
 Ulceration which is the usual outcome of active diseaseUlceration which is the usual outcome of active disease
 Noncaseating epithelioid cell granulomas are formedNoncaseating epithelioid cell granulomas are formed
 Giant cell may occurGiant cell may occur
 Secondary Fibrosis & muosa undergoes metaplsiaSecondary Fibrosis & muosa undergoes metaplsia
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10.  Noncaseating granulomasNoncaseating granulomas
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11.  Whole mount specimen of Crohn's disease showing transmuralWhole mount specimen of Crohn's disease showing transmural
inflammation with predominance of the inflammation in the mucosainflammation with predominance of the inflammation in the mucosa
and submucosa.and submucosa.
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12. Pathology Ulcerative colitisPathology Ulcerative colitis
Uniform and continuous inflammatory process of the colonic mucosaUniform and continuous inflammatory process of the colonic mucosa
↓↓
Ulcerations (shallow) & pseudo polypoidal changes (islands of regeneratingUlcerations (shallow) & pseudo polypoidal changes (islands of regenerating
mucosa bulge upwardmucosa bulge upward
↓↓↓↓
Hypertrophy of muscularis mucosa & contraction of colonic musculatureHypertrophy of muscularis mucosa & contraction of colonic musculature
↓↓
Shortening & narrowing of the colon with loss of haustrationShortening & narrowing of the colon with loss of haustration
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13. M/EM/E
 A diffuse, predominantly mononuclear inflammatory infiltrate of theA diffuse, predominantly mononuclear inflammatory infiltrate of the
mucosa & submucosamucosa & submucosa
 crypt abscesses may occurcrypt abscesses may occur
 In late stages, granulation tissue fills in the ulcer craters, followed byIn late stages, granulation tissue fills in the ulcer craters, followed by
regeneration of the mucosal epitheliumregeneration of the mucosal epithelium
 Submucosal fibrosis and mucosal architectural disarray and atrophySubmucosal fibrosis and mucosal architectural disarray and atrophy
remainremain
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14. Crypt Abscess - UCCrypt Abscess - UC

15. 1515
Ulcerative colitis. Chronic form, showing mucosal ulceration with
residual foci of elevated and hyperemic mucosa.

16. 1616
Ulcerative colitis. Acute form with marked hyperemia.

17. 1717
Pseudopolyps in ulcerative colitis.

18. Toxic megacolonToxic megacolon
 severe colonic dilation (toxic megacolon) with potential rupturesevere colonic dilation (toxic megacolon) with potential rupture
 Exposure of the muscularis propria and neural plexus to fecalExposure of the muscularis propria and neural plexus to fecal
material also may lead to complete shutdown of neuromuscularmaterial also may lead to complete shutdown of neuromuscular
functionfunction
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19. FeaturesFeatures Ulcerative ColitisUlcerative Colitis Crohn`sCrohn`s
DiseaseDisease
 SiteSite Colon Any part of GITColon Any part of GIT
 Rectal involvementRectal involvement over 90%over 90% Rectum spared > 50%Rectum spared > 50%
 Terminal ileum involvementTerminal ileum involvement 10%10% 30%30%
 Continuity of lesionContinuity of lesion continuouscontinuous Segmental (skip lesion)Segmental (skip lesion)
 PolypsPolyps Common UncommonCommon Uncommon
 FistulaeFistulae Rare Very CommonRare Very Common
 SinusesSinuses AbsentAbsent CommonCommon
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20. FeaturesFeatures Ulcerative ColitisUlcerative Colitis Crohn`sCrohn`s
DiseaseDisease
 Intestinal haemorragheIntestinal haemorraghe CommonCommon RareRare
 MucosaMucosa Granular,Granular, Discretely ulceratedDiscretely ulcerated
ulcerated mucosa mucosa, cobblestoneulcerated mucosa mucosa, cobblestone
 Wall thickeningWall thickening Moderate MarkedModerate Marked
 Bowel lengthBowel length shortenedshortened usually normalusually normal
 GranulommaGranulomma absentabsent in 60in 60 –– 70%70%
 Anatomical LayersAnatomical Layers Preserved LostPreserved Lost
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