Pathology of Inflammatory Bowel Disease

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  • Created by: LBCW0502
  • Created on: 12-10-19 15:32
State aspects of the gastrointestinal tract
Oesophagus, stomach, liver, pancreas, gall bladder, SI, LI
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State aspects of the small intestine
Transverse colon, ascending colon, descending colon, ileum, sigmoid colon
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What is IBD? (1)
Ulcerative colitis and Crohn's disease. Idiopathic, chronic, inflammatory diseases of the bowel. Follow a course of flares and remission of symptoms. Small number of cases associated with extra-intestinal features
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What is IBD? (2)
Distinct differences between UC and CD in genetic susceptibility, pathology, disease course and use of disease specific targeted therapies
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What is IBD? (3)
Inflammatory disease of the bowel. Idiopathic and chronic. Relapse and remission. Distinct differences between UC and CD. (5% of IBD patients unclassifiable)
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What is Crohn's Disease?
Can affect any part of the GIT, patchy, transmural inflammation. Defined by location or by pattern (inflammatory, fistulating or stricturing)
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What is Ulcerative Colitis?
Diffuse mucosal inflammation, limited to colon, broadly divided into distal and more extensive disease. Not associated with fistulae or fissures
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Describe the epidemiology (1)
Disease of developed areas but becoming more common in the rest of the world. UK incidence of 1 in 500 suffer from IBD. Mainly young adults with peak onset of 20-40 years. Both diseases can occur at any age (UC more common in elderly)
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Describe the epidemiology (2)
Incidence of Crohn's Disease of 83 per million people per year in the UK, UC is 10 per 100,000 people every year
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Describe the aetiology (1)
Unknown - heterogenous disease, genetic abnormalities, immune response, bacterial infective to environmental. Immunological - inappropriate/on-going activation of mucosal immune system due to defects in barrier function of intestinal epithelium
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Describe the aetiology (2)
Defects in mucosal immune system, defects in bacterial clearance. Results in autoimmune inflammation of intestinal tract
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Describe the genetics of Crohn's Disease
Variation of CARD 15 gene on chromosome by 16 increases risk of CD by 20-30%. More likely to develop CD if there is a close member of family with disease. High prevalence in Ashkanazi Jews. More common in Caucasians than Blacks or Asians
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Describe the genetics of Ulcerative Colitis
Variation of HLA gene on chromosome 6. Variation in IL10 gene on chromosome 1. Variation in ARP2C region on chromosome 2. 1 in 4 patients with UC have a strong family history. Higher prevalence in some ethnic minorities. South Asians
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Describe the environmental effects on CD (1)
Smoking increases risk of CD and worsens disease. Highest number of cases in western parts of the world. Western diet has a role (hygiene, reduce infection). Food cold chain (use of refrigerators). MAP mycobacterium avium (survive in pasteurisation)
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Describe the environmental effects on CD (2)
Drugs - oral contraceptive pill has been linked. NSAIDs may precipitate a relapse
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Describe the environmental effects on UC
Smoking is protective in UC, possibly attributed to nicotine or carbon monoxide. Highest number of cases in western parts of the world. Western diet has a role (hygiene, reduce infection). Pollution as a cause. NSAIDs may precipitate a relapse
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Describe features of aetiology - dysbiosis, psychogenic, host immune response (1)
Dysbiosis - abnormal ratio of good and bad bacteria due to defective mucosal barrier function, and defective microbial clearance. Psychogenic - 40% of UC cases e.g. stress (alter mucosal permeability and blood flow, cytokines)
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Describe features of aetiology - dysbiosis, psychogenic, host immune response (2)
Host immune response - both CD and UC patients have activated innate (macrophage, neutrophil) and acquired (T and B cell) immune responses and loss of tolerance to enteric commensal bacteria
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Describe features of aetiology - dysbiosis, psychogenic, host immune response (3)
Leading to enhanced production of pro-inflammatory cytokines and chemokines (IL-12, IL-18, TNFa)
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Describe the pathology of of IBD (1)
Acute injury and inflammation, a patient with no genetic factor will heal (back to normal condition). A patient with a genetic factor - reduced immunoregulation failure of repair or bacterial clearance, leads to chronic inflammation
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Describe the pathology of of IBD (2)
Both CD and UC have activated innate and acquired (T and B cell) immune responses and loss of tolerance to enteric commensal bacterial. Distinct difference between UC and CD in cytokine mechanism in which mucosal inflammation is controlled/pathology
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Describe the pathology of of IBD (3)
CD - TNFa, IFN gamma, IL-1 etc, innate immune response - IL-1 beta, TNF, IL-6, Il-12, IL-23, IL-27, T-cell response - IFN gamma, IL-17, IL-21. UC - IL-5, IL-10, TNFa, innate immune response - IL-1 beta, TNF, IL-6, IL-18, T cell response - IL-5, IL-13
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What is Crohn's Disease?
Chronic progressive patchy inflammation of gut wall. May occur anywhere along GI tract (most common- ileum and colon). Transmural, chronic inflammation. Hyperplasia/luminal invasion. Patchy ulceration. Strictures (10-15%). Fistulae (15-20%). RLQ mass
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What is Ulcerative Colitis? (1)
Chronic progressive generalised epithelial ulceration. Distal disease (rectum or sigmoid colon) or more extensive (L-sided colitis, whole colon - pancolitis). Superficial continuous inflammation (mucosa only)
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What is Ulcerative Colitis? (2)
Inflammation limited to colon and starting at a. Most cases limited to left side. No perianal disease - fistulae, perforation, fissures
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What is the pathology of CD and UC?
CD - affects any part of the GI system. UC - affects any part of the small intestine
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Which technique is used to diagnose IBD?
Endoscopy - use a camera to view the GI system
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What are the clinical features of CD affecting the ileum (viewed during endoscopy)?
Mucosal inflammation, redness, friability, oedema, granular appearance, cobblestone appearance
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What are the clinical features of UC affecting the ileum (viewed during endoscopy)?
Mild colitis (redness and swelling of mucosa). Overall granular appearance and friability (fragility with ease of bleeding)
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What are the complications of Crohn's Disease? (1)
Strictures - luminal narrowing, experience abdominal pain, constipation, vomiting (procedures can be carried out to widen lumen)
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What are the complications of Crohn's Disease? (2)
Fistulae - abnormal channel between two tissues/organs. Could lead to infections
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What is extra-intestinal disease?
Affects 4% of IBD patients. Includes - erythema nodosum, pyoderma gangrenosum, primary sclerosing cholangitis, ankylosing spondylitis, 15-20% arthropathy affecting large joints (hips, knees). Osteoporosis, uveitis
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What are the clinical features? (1)
CD more serious/debilitating, acute UC can strike quickly/lead to hospitalisation and surgery. UC/CD can co-occur, but if colon is affected in CD than difficult to differentiate from UC. Features depend on site/extend of disease
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What are the clinical features? (2)
Initial episode of IBD usually most severe that a patient will experience. Impact on patient - embarrassing, lack of confidence to leave house, psychological problems etc
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What are the clinical features of CD? (1)
Acute/insidious onset of symptoms (heterogeneous), mild-moderate, moderate-severe, severe-fulminant. Weight loss, fever, general malaise/tiredness. Sometimes diarrhoea. Abdominal pain - RLQ or central. Palpable tender mass - lower abdomen
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What are the clinical features of CD? (2)
Malabsorption, hypovitaminosis, anorexia, frequently perianal disease, abscess - fistulas
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What are the clinical features of UC?
Often abrupt onset with some chronic symptoms (mild/moderate/severe/fulminant). Severe diarrhoea with blood and mucous colic and urgency. Left sided pain. Anaemia. Nausea/vomiting. Dehydration. Lower abdominal cramps and pain on defaecation. Fever
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Which disease activity scores are used? (1)
Harvey Bradshow Index used for CD (score 0-3 for abdominal pain, general wellbeing, abdominal mass, extra colonic features). Simple clinical colitis activity index for UC (score 0-4 for bowel frequency, nocturnal frequency, urgency, blood in stool,
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Which disease activity scores are used? (2)
(general wellbeing, extra colonic features) - monitoring effectiveness of treatment
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Which investigations are carried out? (1)
History (recent travel, medication, smoking, FH, stool frequency, consistency, rectal bleeding etc.). Examination (general well being, pulse rate, temperature, BP, abdominal tenderness). Blood tests - FBC, albumin, serum iron, serum B12, urea
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Which investigations are carried out? (2)
Electrolytes, ESR (indication of chronic infections), CRP (indication of acute infections), any small change in CRP is significant
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Which investigations are carried out? (3)
Imaging - sigmoidoscopy/colonoscopy, barium meal, CT, MRI. Stools culture to rule out C. Difficile. Faecal calprotectin
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What is faecal calprotectin?
Substance release when there is lots of inflammation in the bowel (stool test – monitor effectiveness of treatment instead of using an endoscopy)
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Which investigations are carried out? (4)
Disease activity scores- UC - SCCAI, mayo score - examines stool frequency, rectal bleeding, endoscopic findings). CD - HBI, Crohn's Disease Activity Index - examines general well being, abdominal pain, stool frequency etc.
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What is the course and prognosis for IBD?
10% spontaneous complete remission. 70% relapse and progression. 20% chronic active course of disease
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What is the course and prognosis for CD?
70-80% need surgery within their lifetime. Symptoms recur after surgery in 35% patients within 5 years. Life expectancy slightly reduced. Surgery not always possible depending on where disease occurs
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What is the course and prognosis for UC?
Surgery better outcome than CD. Normal life expectancy with stable disease
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What are the complications with CD?
Malabsorption (anaemia), small bowel obstruction, perforation, fistulating disease and abscess (bladder, vagina, skin), small/large bowel cancer, screen after 8 years. 35% of patients develop lactose intolerance, osteoporosis
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What are the complications with UC?
Fluid/electrolyte imbalance. Toxic megacolon/life-threatening - UC (5%), severe bleeding and anaemia. UC is risk factor for colorectal cancer. 20-25% may need colectomy. Use of stoma bag
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State aspects of the small intestine

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Card 3

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What is IBD? (1)

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Card 4

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What is IBD? (2)

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Card 5

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What is IBD? (3)

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