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Path: inflamm diseases of bowel (iii) (UC (may have extra-intestinal…
Path: inflamm diseases of bowel (iii)
Crohn's
affects 1-3 in 100000 annually
esp western pops, females, whites, Jews
peak incidence in teens/20s, with a minor peak in 50s-60s
affects any portion of GIT (from mouth to anus), most commonly terminal ileum (hence called regional ileitis)
segmental involvement - skip lesions - partially normal segments (not continuous)
transmural involvement of bowel wall (all layers affected)
creeping fat (locally restricted hyperplasia of mesenteric fat adjacent to inflamed segments of intestine)
dull inflamed serosa
thickened wall (due to oedema, inflamm + fibrosis)
strictures/narrow lumen
aphthous mucosal ulcers that coalesce into long, linear serpentine ulcers along bowel axis - linear ulcers with oedema of the intervening mucosa gives a raised "cobble-stone" appearance
fissures (deep penetrating ulcers in bowel wall)
fistulae (abnormal connection between 2 epithelial surfaces - due to adhesion formation seoncdary to inflamm) or sinus tracts
chronic mucosal damage - crypt architectural distortion
mucosal ulceration + fissuring
inflamm
transmural
cryptitis (neutrophils in the wall of the crypt)
crypt abscess (neutrons in the lumen of the crypt)
lymphoid aggregates
+/- non-caseating granulomas - seen in 40-50%, epithelioid macrophages forming Langhan's giant cells
possible dysplasia late in disease (rare)
clinical features
variable - relapsing + remitting course
intermittent attacks of diarrhoea, abdo pain, fever
attacks precipitated by emotional stress
occult or overt faecal blood loss - microcytic anaemia (Fe deficient)
B12 malabsorption (as is absorbed in terminal ileum) - megaloblastic anaemia
weight loss
may have extra-intestinal (systemic) manifestations
migratory polyarthritis
sacroiliitis - inflamm of sacroiliac joints
ankylosing spondylitis - can cause some vertebrae to fuse
erythema nodosum (type of septal panniculitis - painful nodules on shins)
clubbing on finger tips
dx: small bowel or colon bx
complications
obstruction, commonly @ terminal ileum (secondary to transmural fibrosis/stricture)
adhesions (excess fibrin produced as inflamm mediator - glue-like)
fistula formation involving adjacent small bowel, colon, bladder, vagina, abdo + perianal skin
malabsorption with steatorrhoea (secondary to mucosal disease + surgical resection
generalised malabsorption (B12 + bile salts)
increased risk of carc (slight, not as much as UC) - approx 5-6 fold increase over controls
UC
chronic inflamm disease confined to colon
limited to mucosa + submucosa of large bowel
incidence = 4-12 in 100000 annually
affects Caucasians, equal sex predilection, all ages (peak incidence 20-25 y/o)
may have extra-intestinal manifestations
migratory polyarthritis
sacroilitis
ankylosing spondylitis
erythema nodosum
pyoderma gangrenosum (necrotising skin lesion)
clubbing
PSC
uveitis
more common in UC than Crohn's
usually begins in rectum + extends proximally in a continuous fashion (no skip lesions)
may involve entire colon (pancolitis)
red mucosa
large areas of ulceration confined to mucosa - often extensive + broad-based (not linear)
isolated islands of regenerative mucosa (GIT cells are labile - readily prolif + regenerate)
inflamm pseudopolyps
wall not thickened (not transmural inflamm)
normal serosa
cryptitis + crypt abscesses
ulceration
architectural distortion of crypts (irregular shapes instead of round)
may show epithelial dysplasia (normal -> inflamm -> high or low grade dysplasia -> adenocarc)
no granulomata
clinical features
relapsing + remitting
episodes may be precipitated by stress
intermittent attacks of bloody mucoid diarrhoea, abdo pain, tenesmus
fever + weight loss
anaemia (blood loss - Fe deficient)
Dx = colon Dx
complications
toxic megacolon
acute dilation of colon due to toxic damage to musclularis propria + neural plexus
shutdown of neuromuscular function - functional obstruction
markedly increased cancer risk
related to extent of colonic involvement + duration of disease (preceded by dysplasia)
esp if duration > 10 yrs (x20 risk)
regular endoscopy + biopsy