IBD and diarrhoea Flashcards
Four mechanisms of diarrhoea:
- Osmotic
Presence of poorly-absorbed solutes in gut lumen - Secretory
Abnormal ion transport –> water secretion - Exudative / inflammatory
Disruption of mucosal barrier (infection / idiopathic inflammation) - Motility-related
What is dermatitis herpetiformis?
With which GI condition is it associated?
Dermatitis Herpetiformis:
- AKA Duhring disease
- Rare but persistent blistering skin condition
- ‘immunobullous’: blistering condition caused by an abnormal immunological reaction
- extremely itchy bumps (prurigo papules) and blisters (vesicles), which arise on normal or reddened skin.
- often scratched –> erosions and crusting –> resemble dermatitis or scabies
- Older lesions may leave pale or dark marks (hypopigmentation and hyperpigmentation)
- Related to coeliac disease
- It involves IgA antibodies and intolerance to the gliaden fraction of gluten found in wheat, rye and barley
- Eighty percent of patients with dermatitis herpetiformis also have gluten enteropathy
Dermatitis herpetiformis often affects young adults; two thirds of patients are male. There is a genetic predisposition; there are associations with human leukocyte antigens (HLAs) DQ2 DQ8.
What is pyoderma gangrenosum?
With which GI conditions is it associated?
Pyoderma Gangrenosum:
- uncommon cause of very painful skin ulceration
- lower legs are the most common site
- more common in those aged over 50 years.
- starts quite suddenly, at site of minor injury.
- may start as a small pustule, red bump or blood-blister. The skin then breaks down resulting in an ulcer. The ulcer can deepen and widen rapidly. Characteristically, the edge of the ulcer is purple and undermined as it enlarges.
- It is usually very painful.
One of the neutrophilic dermatoses:
- dense infiltration neutrophils
- arise in reaction to some underlying systemic illness
- often arise at the site of injury such as a needle prick, biopsy or insect bite
The name pyoderma gangrenosum is historical. The condition is not an infection (pyoderma), nor does it cause gangrene.
~50% associated with one of:
- IBD (US or Crohn disease)
- Chronic active hepatitis
- Rheumatoid arthritis
- Myeloid blood dyscrasias
- Wegener granulomatosis
- PAPA syndrome
- others
Untreated ulcers may:
- continue to enlarge
- persist unchanged
- may slowly heal (often cross-shaped pattern).
Treatment is usually successful in arresting the process, but complete healing may take months.
What is erythema nodusum?
With which GI conditions is it associated?
Erythema nodosum:
- skin condition where red lumps form on the shins, and less commonly the thighs and forearms
- a type of panniculitis, i.e. an inflammatory disorder affecting subcutaneous fat.
- hypersensitivity reaction with a number of different causes
- peak age 20-30. F>M.
Most people with erythema nodosum are otherwise in good health but it is often associated with recent infection or illness.
Common causes:
- IBD (UC / Crohns)
- Throat infections (streptococccal, viral)
- Bacterial infections, eg. Mycoplasma pneumoniae.
- Sarcoidosis (Lofgren’s syndrome) - cough & SOB
- TB (primary infection)
- Pregnancy or OCP
- Drugs, including: sulphonamides, saliclyates, NSAIDs, bromides, iodides and gold salts.
- other causes
Red lumps appear on the shins or about the knees and ankle. They vary in size between a cherry and a grapefruit and in number from 2 to 50 or more. Usually there are 6-12 lumps on the front and sides of the legs and knees. The nodules are slightly raised above the surrounding skin; they are hot and painful, bright red when they first appear, later becoming purple then fading through the colour changes of a bruise.
Erythema nodosum nodules continue to erupt for about 10 days. The “bruising” colour-change starts in the second week, becomes most marked in the third week, then subsides at any time from the end of the third week to the sixth week. Aching of the legs and swelling of the ankles may persist for some weeks, especially if the patient does not rest up. New crops of erythema nodosum may occur over a number of weeks. Rarely, 2 or 3 large lesions merge to form a crescentic ring, which spreads for some days before fading.
Other symptoms may include:
- Fever, malaise, myalgia, arthralgia (esp. knees)
- Conjunctivitis is less frequent.
Pathogenesis of IBD:
Thought to likely be due to abnormalities in the normally controlled immune response to commensal bacteria of genetically predisposed individuals.
Tcell subsets predominantly involved with Crohns vs UC:
CD: Th1, T17
UC: Th2
NOD2 gene polymorphism has an association with which GI condition?
Increases risk of Crohns disease.
Classification of ulcerative colitis
Montreal Classification:
Extent:
E1 = Ulcerative proctitis (limited to rectum)
E2 = Left-sided / distal UC (distal to splenic flexure)
E3 = Extensive US (pancolitis) = involvement extends proximal to the splenic flexure
How is Crohn’s disease classified?
Montreal Classification:
Variables:
- Age at Dx (40yo)
- Locations (ileal / colonic / ileocolonic / isolated upper)
- Behaviour (none / stricturing / penetrating / perianal disase modifier)
Complications of severe acute colitis:
- Toxic dilatation
….
‘M rule’ for Primary Biliary Cirrhosis
IgM
AntiMitochondrial Abs - M2 subclass
Middle aged females
