IBD/polpys/diverticula/crc Flashcards
(46 cards)
Which is more common: Crohn’s disease or ulcerative colitis? WHen is peak incidence?
The incidence of Crohn’s disease 5-7 per 100,000 compared to 10 per 100,000 for UC. For
both diseases the peak incidence is in young adults with a second peak incidence in the 7th
decade.
What is the pathogenesis of IBD?
There are numerous theories, but the most commonly quoted pathogenesis is an
environmental trigger in a genetically susceptible individual
What are the differences between Crohn’s and UC in terms of anatomical site involved?
Crohn’s disease can affect the whole GI tract from the mouth to the anus. The majority suffer from perianal disease
UC is generally confined to the colon +/- backwash ileitis. Only a minority develop perianal disease
What pathological features would you expect to find in a surgical specimen from a patient
with Crohn’s disease?
Macroscopically:
–>Cobblestone appearance, in which oedematous islands of mucosa are separated by crevices or fissures
–>Skip lesions.
–> Sinus or fistula formation.
–>Full thickness bowel wall involvement
Microscopically:
–>there are deep fissuring ulcers
–>non-caseating granulomas
What pathological features would you expect to find in a surgical specimen from a patient
with UC?
Macroscopic:
-Continuous involvement of bowel, compared with skip lesions in Crohn’s disease
-Pseudopolyps
Microscopic
-Crypt abscesses
-Inflammation only affects the mucosal layer of the GI tract (hence the lack of fistulas compared with Crohn’s disease)
What are the extra-intestinal manifestations of IBD?
Eyes: Conjunctivitis, episcleritis, anterior uveitis
Liver and biliary tree: Fatty liver, cirrhosis and (only in UC) PSC and choleangiocarcinoma
Renal tract: Calculi
Joints: Arthropathy and (only in Crohn’s) ank spond and sacroiliitis.
Other features: Finger clubbing, erythema nodosum, pyoderma gangrenosum, aphthous
ulcers, increased risk of DVTs/PEs.
What are intestinal polyps?
A polyp is a pedunculated mass of tissue arising from an epithelial surface.
How are polyps classified?
Polyps can be classified into non-neoplastic or neoplastic.
Non-neoplastic: Metaplastic, hamartomatous, inflammatory pseudopolyps (present in
ulcerative colitis)
Neoplastic: Tubular, tubulo-villous, villous.
Of the neoplastic polyps, which is the most frequently encountered type?
The order of frequency is as presented in the previous question: Tubular, tubulo-villous then
villous, in order of decreasing frequency
Which of the neoplastic polyps has the most malignant potential?
Malignant potential is in the reverse order i.e. in order of decreasing malignant potential:
Villous, Tubulo-villous, then Tubular
What complications might polyps undergo?
Malignant transformation
Ulceration
Bleeding
Infection
Intussusception
Protein and potassium loss
What is FAP?
-Autosomal dominant
-Loss of APC tumour supressor gene
-lots of tubular adenomas
-almost 100% chance ca by age 40
This picture is likely to represent the bowel of someone with familial adenomatous polyposis
(FAP), as there are hundreds of adenomatous polyps. FAP is an autosomal dominant
condition characterized by the loss of the APC tumour suppressor gene on chromosome 5,
resulting in 100s to 1000s of tubular adenomas. This predisposes them to a near 100% risk of
GI cancer by the age of 40.
What other features might someone with FAP have?
FAP is associated with small bowel periampullary polyps and mandibular osteomas.
In the related Gardner syndrome patients have osteomas of the skull, epidermoid cysts,
multiple desmoids tumours (soft tissue tumours) and abnormal retina pigmentation.
This gentleman’s younger sister also has FAP. How would you manage them initially?
His sister will require full assessment and counselling initially, followed by regular LGI endoscopy, before eventual colectomy
How frequently and starting at what age would endoscopic surveillance start?
-Flexi sig every 1-2 yrs from age 12
-Once polyps observed: colonoscopy at similar intervals with polypectomy of larger polyps
Patients with FAP have flexible sigmoidoscopy every 1-2 years from age 10-12. Once polyps
are observed, they will have colonoscopy at similar intervals with polypectomy of larger
polyps.
At what age are patients offered an operation?
A prophylactic near total colectomy is offered around age 25. This is to allow them to reach
an appropriate age to cope psychologically. However, if the polyps removed at colonoscopy
have advanced histological features, then earlier surgery will be offered.
What sort of procedure is most commonly performed for UC?
A panproctocolectomy with ileoanal pouch formation is the most frequently performed
procedure.
What surveillance would be required following pan procto-colectomy and ileo-anal pouch for FAP?
-UGI endoscopy every 3-5 years and sigmoidoscopy with ablation of any polyps in pouch
-Regular clinic fup for extracolic manifestations
Following this, she will continue to require an upper GI endoscopy every 3-5 years, and a
sigmoidoscopy with ablation of any polyps in the ileoanal pouch (or retained rectum if a
subtotal colectomy is performed). She should also have regular clinic follow up to screen for
extracolic manifestations.
Are there any medications that decrease the number of polyps in FAP?
Celecoxib and sulindac are two medications that have been used to reduce the number and
the size of polyps in FAP.
What is a hamartoma?
-Tumour like malformation
-Composed of disorganised tissues normally found at that site
-Grows under normal growth controls
A hamartoma is a tumour-like malformation composed of a disorganised arrangement of
different amounts of tissue normally found at that site. It grows under normal growth
controls.
Examples: Haemangiomas; lipomas
If a specimen had shown multiple hamartomatous polyps what would the likely
diagnosis have been? Describe this condition
-Peutz jeghers
-Autosomal dominant
-Multiple intestinal hamartomatous polyps
-Increased risk of breast, lung, uterus and pancreatic ca
-pigmented macules on lips and perioral skin
The likely diagnosis would be Peutz-Jeghers syndrome, an autosomal dominant syndrome
characterized by multiple intestinal hamartomatous polyps, increased risk of breast, lung,
uterus and pancreatic cancer, and pigmented macules on the lips and the perioral skin.
Will a pt with peutz-jegher’s also need a prophylactic colectomy?
In Peutz-Jeghers the malignant potential is low, therefore a prophylactic resection is not
recommended.
What is dysplasia?
Dysplasia is disordered cellular development characterised by increased mitosis and
pleomorphism but WITHOUT the ability to invade the basement membrane and metastasise.
Note: Severe dysplasia = carcinoma-in-situ
In someone without a genetic predisposition, how do colorectal polyps progress to
adenocarcinoma?
Accummulation of genetic defects
Normal cells –> dysplastic cells –> malignant cells that can invade through basement membrane
It is thought to involve an accumulation of genetic defects, whereby there is a progression
from normal cells, to dysplastic cells, to malignant cells that can invade through the basement
membrane.
