GI Pathology: UC + Crohn's Flashcards
Ulcerative collitis and Crohn’s disease are the two major forms of chronic idiopathic inflammatory bowel disease (CIBD). When do both diseases show a peak in terms of age?
- late adolescence and early adulthood
- little gender difference
- more common in white people
Why are both diseases considered idiopathic?
- underlying aeitology + pathogenesis poorly understood
- different aetiologies between two
- although clinical and pathological findings can overlap
What do most investigators believe CIBD results from?
a combination of:
- intestinal epithelial dysfunction
- aberrant mucosal responses in a genetically susceptible host
- altered composition of intestinal flora
Mutations in which gene are thought to be important in the development of Crohn’s?
- NOD2 gene
- product of which is involved in macrophage activation
What is a significant predisposing factor in Crohn’s disease that appears to be protective against UC?
Smoking
What is the diagnostic test for Crohn’s disease and UC?
- there is no single diagnostic test for crohn’s + UC
- accurate diagnosis depends on integration of clinical, endoscopic, microbiological, radiological and histopathological features
- it is important that infective causes of inflammation are considered and excluded
What is the gross appearance of ulcerative collitis?
- only the large bowel (colon + rectum) is affected
- rectum is almost always affected
- disease extends proximally in a continuous distribution to involve a variable amount of colon
- most severely affected mucosa is usually present distally
- proctitis (30%) and distal colitis (30%) are most common
What are microscopic features of ulcerative collitis?
- inflammation generally involves mucosal layer only
- there is extensive, diffuse mucosal ulceration w/ inflammation
- crypt abscesses are a typical feature - crypts full of neutrophils
- granulomas are not seen
What might patients with long-standing UC develop?
- inflammatory polyps (‘pseudopolyps’) - composed of inflammatory tissue - typically granulation tissue permeated by inflammatory cells, they are not dysplastic ie. they are not premalignant
- inc risk of developing colorectal carcinoma - those w greatest risk have extensive collitis + a long history (>8rs) of disease, pts are therefore offered colonoscopic surveillance, aim is to detect + treat dysplasia (ie pre-malignancy) before the development of an invasive adenocarcinoma
What is the clinical presentation of UC?
- bloody diarrhoea (pooing many times a day)
- lower abdo pain + cramps
- can be classified as mild/moderate/severe
- fever in moderate/severe cases
- inc HR in severe cases
- may present with anaemia
What are some extra-intestinal manifestations of ulcerative collitis?
- overlap with those of Crohn’s disease
- include uveitis
- migratory polyarthritis
- sacroilitis
- ankylosing spondylitis
- skin lesions
about 5% of pts with UC also have primary sclerosing chalngitis, these pts are at an increased risk of developing cholangiocarcinoma
What are gross features of Crohn’s disease?
- may affect any part of GI tract from mouth to anus
- preferentially involves the terminal ileum + proximal colon
- distribution is typically patchy + discontinuous (diseased segments are separated by normal areas)
What are the microscopic features of Crohn’s disease?
- deep fissuring ulcers, often in form of penetrating knife-like clefts through bowel wall
- transmural inflammation (ie. all layers of the bowel wall may be involved)
- non-caseating granulomas are often present (but not in every case)
What is a granuloma?
An aggregate of activated (epithelioid) histiocytes (activated macrophages resembling epithelial cells)
How is there a ‘cobblestone’ appearance in Crohn’s?
- linear fissuring ulcers may coalesce (join)
- cobblestones correspond to areas of surviving mucosa
- surrounded by fissuring ulceration
Give 5 major pathological differences between UC and Crohn’s
