Histopathology 16: Lower GI Flashcards
A 2 year old boy with down syndrome presents with symptoms of constipation with overflow diarrhoea and vomiting. There are signs of abdominal distension.
What is the most likely diagnosis ?
Hirschsprung’s disease
Where does Volvulus tend to occur in children? Where does it occur in adults ?
Children= small bowel Adults = Sigmoid colon
Which organism causes pseudomembranous colitis ?
C.difficile
antibiotics kill commensal bacteria and allow C.diff to flourish. It’s endotoxins cause Pseudomembranous colitis
List features of Crohn’s disease ?
- ENTIRE GIT affected (mainly terminal ileum and large bowel)
- Transmural inflammation (all the way through the wall)
- Skip lesions
- Non-caseating granulomas
- Cobblestone mucosa
- Can affect anus to mouth
- Fistula formation
Extra-intestinal (NB also get these in UC):
- Arthritis
- Uveitis
- Stomatitis/ cheilitis
- Skin lesions: erythema multiforme, nodosum
List 5 features of Ulcerative colitis ?
- Involves rectum and Colon but not small bowel
- Inflammation confined to the mucosa (NOT transmural like Crohn’s)
- Inflammation is continuous, no skip lesions
- Backwash ileitis- terminal ileum gets involved
- Can cause toxic megacolon
- ULCERS
- mucosa regenerates forming pseudopolyps
- Crypt abscesses
List 3 skin lesions seen in Crohn’s ?
Erythema multiforme
Erythema nodosum
Pyoderma gangrenosum
List 3 familial syndromes characterised by polyps ?
Familial adenomatous polyposis
Peutz-jeghers syndrome
Hereditary non polyposis colorectal cancer (HNPCC)
Name 2 subtypes of FAP ?
Gardner’s syndrome
Turcot syndrome
List 5 extra-intestinal manifestations of Gardner’s syndrome ?
Gardner’s syndrome: pathological and aetiological features of FAP with a high cancer risk
- Multiple Osteomas of the skull and mandible
- Epidermal cysts
- Desmoid tumours
- Dental carries/ unerrupted supernumerary teeth
- Post surgical mesenteric fibromatoses
List 3 features seen in carcinoid syndrome ?
- Flushing
- Diarrhoea
- Bronchoconstriction / tachycardia
Which test is used to diagnose carcinoid syndrome ?
- 24 hour urine 5-HIAA
Which paediatric disease presents with up to 100 hamartomatous polyps in children <5 years old ?
Juvenile polyposis
List 3 features of peutz-jeghers syndrome ?
- multiple hamartomatous polyps
- freckles around mouth
- mucocutaenous hyperpigmentation
Which staging system is used to stage colorectal adenocarcinoma?
Duke’s staging
- A= confined to bowel wall
- B= through wall of bowel
- C= lymph node metastases
- D= distant metastases
Which tumour marker identifies colorectal cancer ?
CEA
where do 90% of diverticuli occur
left colon
therapy for pseudomembranous colitis
metronidazole or vancomycin
at what sites do ischaemic colitis/ infarction occur
- segments in ‘watershed’ zones
- such as splenic flexure (SMA and IMA), rectosigmoid (IMA and IIA)
list causes of ischaemic colitis
- arterial occlusion
- venous occlusion
- small vessel disease - DM, cholesterol, emboli, vasculitis
- low flow states - shock, haemorrhage
- obstruction - hernia, intussusception, adhesions
list 3 complications of UC
- severe haemorrhage
- toxic megacolon
- adenocarcinoma
list some extra-intestinal features of UC (5)
arthritis
myositis
uveitis/iritis
Erythema Nodosum, PG
PSC
list 3 non neoplastic polyps of the colon and rectum
hyperplastic
inflammatory (pseudo-polyps)
hamartomatous (juvenile, peutz jeghers)
list 3 neoplastic polyps (increase R of cancer) of the colon and rectum
tubular adenoma
tubulovillous adenoma
villous adenoma
list risk factors for the development of cancer from a polyp
size of polyp (>4cm - 455 have invasive malignancy)
proportion of villous component (more villousy = more R)
degree of dysplastic change within the polyp
what is FAP/APC
AD
average age of onset = 25 yrs
minimum 100 polyps (average 1000)
chromosome 5q21, APC TS gene
nearly 100% develop cancer within 10 years
What is Hereditary Non-Polyposis Colorectal Cancer (HNPCC)?
- autosomal DOMINANT condition (uncommon)
- Numerous DNA replication errors
- Get Onset of colorectal cancer at an early age
- High frequency of carcinomas proximal to the splenic flexure
- Multiple synchronous cancers (also endometrium, prostate, breast, stomach)
- Do NOT necessarily get polyps
Is UC or Crohn’s more common?
UC (slightly more)
Mutation causing Familial Adenomatous Polyposis (FAP)
APC tumour suppressor gene on Chromosome 5q21 (FAP gene)
Where is high frequency of carcinomas in HNPCC found?
proximal to the splenic flexure
Most colon cancers are what type?
Sx
adenocarcinoma (98%) - means they come from the glands
- Bleeding
- Change in bowel habit
- Anaemia
- Weight loss
- Pain
- Fistula
Big RF for diverticular disease
low-fibre diet
High intraluminal pressure leads to herniation of the bowel mucosa through weak points in the bowel wall
How to detect C. difficile toxin in Pseudomembranous Colitis
toxin stool assay
Most common vascular disorder of the intestinal tract
Ischaemic Colitis/ Infarction
What are GIT adenomas?
- excessive epithelial proliferations with dysplasia (moving towards cancer)
- has lost control but it has NOT invaded yet so it is not cancer
Histology of Tubular Adenoma
Has stalk + not invaded basement membrane
On histology, difference between pink and purple
Pink = good
Purple = bad
Progression of normal cells to carcinoma in GIT
- Normal -> adenoma -> carcinoma
- Adenomas tend to appear about 10 years before carcinoma
- Risk of cancer is proportional to the number of the adenomas
- Screening and removal of adenoma reduces risk of carcinoma
