Histopathology of GI tract

Question 1

INTESTINE STRUCTURE

i) what are the five layers all the way through the GI tract
ii) which intestine are villi found in?
iii) name three cells found in crypts in large intestines
iv) which cells should only be found in the proxmial colon?
v) which two cells to stem cells replenish? how many days does this take?

Answer 1

i) lumen, mucosa, sub mucosa, muscularis (inner circ and outer longitud), serosa

ii) small intestine (duo > ileum)
- longer vili as you move from duo to ileum
- no villi in the large intestine

iii) goblet cells, columnar epithelial cells, paneth cells, neurendocrine cells (distal colon and rectum)
iv) paneth cells - shouldnt be seen past mid TV colon
v) columnar cells and goblet cells > takes about 7 days

Question 2

THE INTESTINAL CRYPT

i) which cells have granular cytoplasm above the nucleus? after which area are these cells less common?
ii) what are APUD cells

Answer 2

i) paneth cells - common up until hepatic flexure, then more sporadic
ii) neurendocrine cells

Question 3

INFLAMMATORY GRADIENT

i) are more inflammatory cells found prox or distally in the colon?
ii) in which area of the colon are crypts longer and thinner?
iii) are more inflammatory cells found at the lumen aspect or the base?

Answer 3

i) more are seen proximally (asc colon) > diminishes to rectum
ii) long and thin in prox colon and more chunky in distal colon (goblet cells)
iii) more at the lumen compared to the base

Question 4

ACUTE COLITIS

i) how long ago must the insult have been from? why?
ii) is normal crypt architecture maintained
iii) what causes the superficial lamina propria to be more spaced out?
iv) what type of WBC are seen? where are these seen acutely?
v) which type of cells are seen in chronic cell turnover? would you expect to see these in acute colitis

Answer 4

i) less than a week due to stem cell turnover
ii) yes
iii) oedema
iv) neutrophils - acutely they are seen in the surface ep, crytps and lam prop
v) paneth cells and kikcuchi cells - would not expect to see

Question 5

INFECTIVE BACTERIAL COLITIS

i) name three bacteria that cause acute colitis?
ii) what stage of IBD may this be seen?

Answer 5

i) campylobacter, salmonella, shigella, e coli
ii) early stages

Question 6

CHRONIC COLITIS

i) how do the crypts look? is an inflammatory gradient seen?
ii) in which cells do you see hyperplasia? what does this indicate
iii) what is ulcer associated cell lineage
iv) name four differential causes for chronic colitis

Answer 6

i) distorted crypt architecture and loss of inflam gradient
ii) paneth cells/ neurendocrine cell hyperplasia > increased cell turnover if you see these later in the colon
iii) mucosa has been ulcerated, healed and repairing eptihelium comes back looking like gastric mucosa
iv) IBD, drugs (NSAIDs), microscopic colitis (usually due to drugs), diverticular colitis, infectious causes eg syphylis and chlamidya

Question 7

ULCERATIVE COLITIS

i) where does it start and progress to?
ii) what is seen histologically (3) - chronic colitis
iii) name two things that are seen in the crypts
iv) where are plasma cells seen?
v) in which cells are granules on top of nuc? nuc on top of granules?

Answer 7

i) starts at the rectum and progresses proximally (mucosa and submucosa only)
ii) loss of crypt architecture (distortion more severe in rectum), loss of inflam gradient, pres of paneth and neurendo cells, pres of neutrophil polymorphic cells
iii) crypt abscess formation and cryptitis
iv) bottom of the lamina propria (basal plasmacytosis) dx inkeeping with UC/CD

v) gran on top of nuc = paneth
nuc on top of gran = neurendocrine

Question 8

CROHNS DISEASE

i) what appearance is seen macroscopically?
ii) what type of crypt architecture is seen?
iii) is fibrosis seen? what does this lead to
iv) what inflammatory cells are seen?
v) what type of ulcers are seen
vi) what is a hallmark feature

Answer 8

i) cobblestone appearance - patchy
ii) focal loss of crypt archiecture that is transmural

iii) yes - as it perforates the sub mucsa
- causes stricturing problems

iv) polymorphic neutrophils within the crypts
- mural abscess formation

v) rose thorn fissuing ulcers
vi) granuloma formation (non caseating)

bowel responds the same to most insults - hard to differentiate between UC and CD on a single biopsy

Question 9

COELIAC DISEASE

i) what happens to the villi? how does this contribute to CD
ii) how is the inflam gradient affected
iii) which cells are not seen microscopically

Answer 9

i) T cells destroy them - cant be replaced quick enough - villous atrophy
- cant absorb nutrients

ii) it is lost and get crypt hyperplasia as it tries to recover
iii) neutrophil polymorphnuclear cells - if they are there is it parasitic