Lower GI disease Histopath Flashcards
Commonest place to find diverticulitis
sigmoid colon
pseudodiverticuli
do not have all layers of the bowel wall
complications fo diverticular disease
pain
diverticulitis
gross perforation
fistula a(bowel, bladder, vagina)
obstruction
Inflammatory disorders of the large bbowel
acute colitis
- radiotherapyu
chronic colitis
- crohns
Causes of infective colitis
viral e.g. CMV
bacterial e.g. salmonella
protozoal e.g/ entamoeba hystolytica
fungal e.g. candida
pseudomembranous colitis
follows abx therapy
acute colitis with pseudomembrane formation
caused y protein exotoxins of C diff
histology: characteristic microscopic features on biopsy
lab: c diff toxine stool assay
pseudomembranous colitis
pseudo because later is a pseudomembrane made of inflammatory tissue (rather than normal lining)
Vascular disorders of lower bowel
ischaemic colitis/infarcion
- can be acute or chronic
usually occurs In segments in watershed zones e.g. scenic flexure
??also: rectosigmoid (IMA to internal iliac)
Aetiology of ischaemic colitis
arterial occlusion: atherosclerosis
can also occur in low flow states e.g. due to hypovolaemic shock
obstruction
macroscopic appearance of bowel ischaemia
red, ischeamic
IBD
Crohn’s disease and Ulcerative colitis
in the real world there is also indeterminate colitis
IBD RFs
genetic predisposition
infection (mycobacteria, measles)
abnormal host immunoreactivity
microbiome
Path features of Crohns diseaase
skip lesions
mouth to anus
TRANSMURAL INFLAMMATION
fissure, sinus, fistula formation
non-caseating granulomas
cobblestone mucosa
extra intestinal manifestations of crohns diseases
arthriris
uveitis
stomatitis/cheilitss
skin diseases (erythema nodosum, ….)
UC
starts in rectum and colon in contiguous fashion
may see mild backwash ileitis and aappendiceaal involvement but small bowel and
shallow ulcers
…..
Complications of UC
toxic megacolon
severe haemorrhage
adenocarcinoma (20-30% x risk)
extra intestinal manifestations of UC
arthritis
myositis
uveitis/iritis
erythema nodosum
pyoderma gangrenosum
primary sclerosis cholangitis (5.5% in pancolitis)
UC - what cancers are you at increased risk of?
cholangiocarcinoma
adenoacarcinoma
What organ has the highest amount of neuroendocrine cells?
bowel
Commonest tumours of the lower GI
non-neoplastic polyps
neoplastic epithelial lesions
- adenoma
- adenocarcinoma
Types of tumours of the colon and rectum
polyps (non-neoplastic)
hyperplss
xxxx
xxx
Peutz Jeghers
AD inherited syndrom
polyps and pigmentation of the lips and other mucocutaneous surfaces e.g. genitals
increased risk of bowel cancer, other GI cancers
Adenomas of the colon and recutm
tubular adenoma
tuboviolous adenoma
villous adenoma
prevalence of adenomas of the colon
///
tubular adenomas
usually round
can have a stalk (pedunculated polyps)
villous adenoma
xxx
tubovillous adenoma
have features of tubular and villous adenomas
- the more villous, the greater the risk of cancer
Why is diverticular disease common in the west?
low fibre diet
Sx of colon adenomas
usually none
bleeding/anaemia
Familial syndromes for adenocarcinoma of the colon
pouty jeghers
FAAP (familial adenomatous polyposis (gardner’s, turoct))
HNPCC
What is commoner, FAP or HNPCC?
HNPCC
FAP - hereditary pattern?
AD
average onset of FAP?
25
Genetic mutation in FAP
5q21, APC tumour suppressor gene
Mx in FAO
prophylactic colon removal
but still risk of duodenal periampullary Ca, monitor duodenum well
What is Gardner’s syndrome
FAP with extra intestinal manifestations
(osteomas, demoed tumours)
What is Turcot’s syndrome
FAP with ???
hereditary pattern of HNPCC
AD
What happens in FAP?
hundreds, thousands of polyps
HNPCC - stats and what happens
may have polyps
3-5% of all colorectal cancers
eat leases 1 of 4 DNAA mismatch repair genes involved.
HNPCC - where are the colonic cancers most common?
in caecum
what cancers are HNPCC associated with?
colon
endometrium
prostate
breast
stomach
multiple synchronous cancers
Commonest colorectal Ca?
98% are adenocarcinoma
Age in colorectal carconoma
60-79 yo
if <50 consider familial syndrome
aetiology of colorectal carcinoma
familial
diet (low fibre, high fat etc)
lack of exercise
… insert
Grading and staging of colorectal cancer
grade - degree of differentiation
Stage - TNM
TNM - what are the different Ts in colorectal carcinoma?
T1 - submucos
T2 - muscle
T3
T4 - peritoneum
what sort of colon polyps most commonly periscope to adenocarcinoma of the colon?
villous adenoma
