IBD Histopathology Flashcards
What are the main causes of infective diarrhoea?
gastroenteritis/enterocolitis
- bacterial (shigella)
- viral (rotavirus)
-protozoan (giardiasis)
atypical infective agents can cause diarrhoea in immunosuppressed individuals
pseudomembranous colitis can be a complication of C. diff
What are the main hallmark causes of diarrhoea?
inflammation
neoplasia
vascular disease
What are the main inflammatory causes of diarrhoea?
- infective
- Coeliac
- IBD
What vascular diseases can precipitate diarrhoea?
vasculitis
ischaemic enteritis/colitis
radiation enteritis/colitis
(these all damage small blood vessels)
What types of neoplasia may cause diarrhoea?
lymphoma (malabsorption)
distal colon carcinoma (overflow diarrhoea)
neuroendocrine tumour (secretes peptides such as 5-HT/serotonin. These can result in episodic palpitations, flushing and diarrhoea)
What are the main histological features of ulcerative colitis?
- wide, shallow intestinal crypts
- inflammation is limited to mucosa
- mixed acute and chronic inflammation in mucosa
- crypt branching
- crypt abcesses
What intestinal complications may present with ulcerative colitis?
- backwash ileitis (in those with pan-colitis)
- appendix involvement (66%)
- ulceration starts in rectum and spreads proximally
- increased incidence sclerosing cholangitis
What histological features are common to both ulcerative colitis and Crohns?
- mixed acute and chronic inflammation in mucosa
- crypt branching
- crypt abcesses
Where the gross features that distinguish ULCERATIVE COLITIS from Crohn’s?
- only affects colon
- begins distally in rectum, spreads proximally
- may involve entire colon (pancolitis)
- geographical ulcers
- confluent/continuous involvement
- strictures are unusual
What intestinal complications may present with Crohn’s disease?
- patchy involvement of upper GI tract
- skip lesions
- fistula formation which links bowel to other viscera
- appendix involvement (33%)
- fat wrapping: mesenteric fat coats bowel surface
- rectal sparing
- perianal skin tags and fistulas
- cobblestone mucosa
Where the gross features that distinguish CROHN’S from UC?
- ileum involvement (66%) - hosepipe thickening of terminal ileum
- colon involvement (33%), mainly right sided
- usually spares rectum but anus often involved (75%)
- skip lesions
- fat wrapping (on serosal surface)
- strictures
- thickened wall
- fistulae
- cobblestone mucosa
What are the main histological features of Crohn’s?
- deep, fissuring ulcers through entire wall
- lymphoid inflammation (throughout wall)
- granulomas often found in bowel and lymph nodes
- Crohn’s rosary: bead-like lymphoid aggregates in mucosal propria
Describe the nature of the inflammation in Crohn’s
transmural inflammation skip lesions can occur anywhere along GI tract strictures linear ulcers fissures
Describe the nature of the intestinal inflammation in ulcerative colitis
continuous colonic involvement begins in rectum, progression proximally through colon active disease: superficial ulceration inactive disease: atrophy pseudopolyps
What are the different types of ulcerative colitis?
proctitis: only rectum
proctosigmoiditis: rectum and sigmoid colon
distal colitis: only left side of colon
pancolitis: entire colon
backwash ileitis: distal/terminal ileum
What are the main clinical features of UC?
typical: diarrhoea with blood and mucus
may present with toxic megacolon
What is toxic megacolon?
acute form of colonic distension
megacolon = dilated colon
Sx: abdo pain, bloating, fever, tachycardia, dehydration
Tx: colectomy if severe, otherwise conservative management using steroids and fluid resuscitation, antibiotics for sepsis
What are the clinical features of Crohn’s disease?
typical: abdo pain, diarrhoea, abdo mass, weight loss
What extra-intestine features are present in UC?
Anaemia fever PSC uveitis ankylosis spondylitis and sacro-iletis pyoderma gangrenousum
What are the extra-intestinal features in Crohn’s disease?
anaemia fever anterior uveitis aphthous ulcers seronegative arthritis erythema nodosum anal skin tags perianal fistulae
What are the short and long term risk of UC?
short: anaemia, toxic megacolon, perforation, peritonitis
long: colonic adenocarcinoma
What is the risk of colonic adenocarcinoma in UC?
risk is proportional to length of inflamed colon
history and duration of disease
What are the short and long term risk of Crohn’s?
short: intestinal obstruction, fistulae, pericolic abscess
long: colonic adenocarcinoma, small bowel lymphoma
What is an aphthous ulcer?
recurrent round or oval sore/ulcer
inside the mouth or where skin is not tightly attached to the bone
similar to canker score
in Crohn’s patients, they may appear concomitantly with intestinal inflammation flare ups
What is the complication of an aphthous ulcer?
It can deteriorate into a granuloma
sloughing of intestinal mucosal debris
scar tissue
What is the hallmark histological appearance found in Crohn’s disease?
cobblestone mucosa
= irregular nodular appearance of mucosa
with hyperaemia and focal superficial ulceration
What is hyperaemia?
increase of blood flow to a given tissue
clinically hyperaemia presents as erythema
Occurs physiologically through vasodilation
What investigations are performed to Dx IBD?
Blood tests Stool tests Endoscopy Radiography Biopsy
What lab results are indicated in the Dx of IBD?
- haemogram
- CRP increased
- ESR increased
- platelets increased
- Hb decreased
- faecal calprotectin levels correlate with histological inflammation
How can faecal calprotectin help in IBD monitoring?
levels will correlate with histological changes
Can also predict relapses and detect
pouchitis
What is pouchitis?
inflammation of the ileal pouch (artificial rectum surgically created out of ileal tissue in patients who have had a colectomy)
Some evidence t suggest link between FODMAP diet and risk of pouchitis
What is the histology characteristic of UC?
- mucosal inflammation (superficial ulceration)
- distorted architecture
- superficial ulcers
- granuloma are absent or affecting mucosa only
What is the histology characteristic of Crohn’s?
- transmural inflammation
- patchy inflammatory architecture with skip lesions
- deep ulcerative fissures
- mucosal and transmural granulomas
What are genetic factors are there for IBD?
UC: more common with HLA-DR2 alleles
Crohn’s: more common in DR5/DQ1 alleles
3-20x higher incidence in 1st degree relatives
What colonic complications are present with UC?
bleeding cancer strictures perforations toxic megacolon pseudopolyps haemorrhoids
What are the intestinal complications in Crohn’s?
cancer fistula abscess perforation stricture
What surgical treatment options are available for Crohn’s disease?
iliocaecal resection segmental resection colectomy and ileorectal anastomosis temporary loop ileostomy proctocolectomy stricturoplasty
What are the other forms of IBD, other than UC and Crohn’s?
collagenous colitis/lymphocytic colitis
ischaemic colitis
infective colitis
indeterminate colitis
