Urticaria/Itch Flashcards
Where is the pathology in urticaria?
Dermis
Where is the pathology in angioedema? Why is this relevant?
Subcutaneous
More potential space to fill with fluid -> more swelling -> takes longer to resolve.
Arbitary cut offs for acute vs chronic urticaria?
6 weeks
Most crucial point from history re: dx of urticaria?
‘Moves around’ (lesions resolve in 24hrs)
If see acute urticaria in developing countries - think of?
Helminthic worm infections -treat regardless as very likely
What see in pictures of wheals?
Why is the middle often lighter?
Normal epidermal markings
Extra oedema masks the vasodilation
What other disease are mucosal polysaccharides implicated in?
Hypothyroidism (myxoedema)
What is in a mast cell’s granules?
Many things inc - histamine, leukotrienes, cytokines, heparin, etc
What can degranulate a mast cell?
IgE, IgA/IgG - autoantibodies and codeine etc etc
Describe spectrum of disease from physiological to pathological cholinergic urticaria?
Normal: strenuous exercise induced papules
Pathological: Light exertion, massive wheals etc
Treatment options for chronic urticaria
Avoid triggers
Anti-histamines (often H1 and H2)
Anti-leukotrienes
Serotonin anatagonists (NB - do not understand MoA)
What drug to be aware of if patient presents with angioedema?
Ace inhibitors
Common anapylactic precipitants?
Shellfish
Nuts
Aceinhibitor reaction (1 in 600) or C1 esterase deficiency
How else can AceI angioedema present?
Anywhere! Eg abdo pain and vomiting due to small bowel angioedema.
What mechanism is proposed behind cough with ACEi?
Bradykinin (look up flaws between this and angioedema being the same MoA)
Which situations are non-sedating anthistamines useful for reducing itch?
Insect bite or urticaria
Do no cross BBB
How many legs do scabies have?
8
Scabies in immunosuppressed patients?
Norwegian or crusted
Mast cell stabiliser?
Sodium chromoglycate
When is sodium chromoglycate used?
In eye drops for hayfever?
In nasal spray
Given oral for gut?
