Urticaria Flashcards
Dermatology
Define urticaria (hives)?
Inflammatory skin condition characterised by wheals
What condition usually occurs with urticaria and why?
Angioedema
Both have same immune process
Define angioedema?
Swelling in subcutaneous tissue (under skin) that lasts up to 3 days
Is urticaria equally common in all ages?
No, less common in children than adults
Does everyone develop urticaria during their lifetime?
No, up to 20% individuals will develop urticaria once in their lifetime
What cell type causes the pathophysiology of urticaria?
Mast cells
How is mast cell degranulation triggered, in the pathophysiology of urticaria?
Autoantibodies/allergens bind to high affinity IgE receptors on mast cells or basophils, or bind to IgE that is already bound to receptor
What 6 substances are released from mast cell granules, in the pathophysiology of urticaria?
Histamines
Proteases
Platelet activating factor
Leukotriene C4
Prostaglandin D2
How does mast cell degranulation cause urticaria symptoms?
Causes plasma leakage from capillaries, which causes swelling and itching
Does urticaria always occur due to the same immune mechanism?
No, can result from different immune mechanisms that have similar presentations
Give 2 examples of immune mechanisms that can cause urticaria?
Type 1 immediate hypersensitivity due to an allergen, which is tested for with skin-prick testing
Type V stimulatory hypersensitivity due to an autoantibody
What is the main difference between acute and chronic urticaria?
Acute urticaria lasts less than 6 weeks
Chronic urticaria lasts more than 6 weeks
Give 7 known causes of acute urticaria?
Food
Medications (NSAIDs, aspirin, codeine)
Insect stings and bites
Viral or bacterial infection
Contact allergy to latex
Transfusion
Vaccination or idiopathic
Does acute urticaria always have a known cause?
No, can be idiopathic
What is the most dangerous complication of severe acute urticaria?
Can progress to anaphylactic shock
What is the difference between chronic inducible urticaria and chronic spontaneous urticaria?
Inducible: Has known trigger
Spontaneous: Has unknown trigger (idiopathic)
Give 5 conditions that can cause chronic inducible urticaria?
Autoimmune conditions eg. urticarial vasculitis
Autoantibodies
Neoplastic
Urticaria pigmentosa
Idiopathic
What type of urticaria is caused by lightly scratching skin?
Symptomatic dermographism: lightly scratching patient’s skin causes raised, inflamed lines or welts that tend to go away in less than 30 minutes
What type of urticaria is caused by sunlight?
Solar urticaria
What type of urticaria is caused by cold air, water or ice?
Cold contact urticaria
What type of urticaria is caused by heat?
Heat contact urticaria
What type of urticaria is caused by sweating?
Cholinergic urticaria
What type of urticaria is caused by pressure?
Delayed pressure urticaria
What type of urticaria is caused by contact with chemicals?
Contact urticaria
What type of urticaria is caused by water?
Aquagenic urticaria
What type of urticaria is caused by vibrations?
Vibratory urticaria
Give 3 causes of why angioedema can present without urticaria?
ACE inhibitor-induced angioedema
Hereditary angioedema (also known as C1 esterase inhibitor deficiency)
Acquired angioedema (which is complement C1q deficiency)
In urticaria presentation, does only one type tend to present?
Different types of urticaria often present together
Describe the typical appearance of wheals, in urticaria?
Superficial non-scaly plaques/swelling that are red or skin-coloured with clear edges
Do wheals always have pale colour and clear edges, in urticaria?
No, can be dark red with annular (prominent) edges
In urticaria, where do wheals tend to appear on body?
Anywhere
How does wheals tend to present in chronic urticaria?
Faded, pink, flat wheals with no palpable swelling that are widespread
How much time does it take for wheals to go down, in the usual presentation of urticaria, and do they leave any marks?
Less than 24 hours
Don’t leave marks, but if chronic there can be very faded marks
How does contact urticaria usually present?
Wheals confined to the contact area, and occurs minutes after exposure
When investigating urticaria, when would you do a skin biopsy?
Suspected urticarial vasculitis
When investigating urticaria, when would you do a skin-pricking test?
Suspected allergen/irritant
How do you use a TempTest to confirm cold or heat contact urticaria?
Patient puts forearm on TempTest for 5 minutes as it maintains temperature range 4-44 degrees celsius, then removes and wait 10 minutes before inspecting skin for urticaria
- Patient develops urticaria around areas that are 4-24 degrees celsius: Suggests cold urticaria
- Patient develops urticaria around areas that are 25-44 degrees celsius: Suggests heat urticaria
How do you use dermographing to confirm systemic dermographism?
Use demographer pen/demographer that is set at different pressure levels to lightly scratch patient’s skin and see after 10 minutes if urticaria develops
No wheals (negative) at pressure 0 but wheals (positive) at pressures 1 and higher indicate dermographism
How can you confirm cholinergic urticaria?
Asking patient to exercise and see if urticaria develops after sweating
How can you confirm solar urticaria?
Phototesting
What scoring tool can be used to measure severity of urticaria?
Urticaria Activity Score (UAS7): 7-day scoring tool for measurement of disease severity
What UAS7 score is needed for a patient to qualify for omalizumab (anti-IgE antibody drug)?
28 or more per week over 2 weeks
And if they have had the omalizumab treatment before, they need to have a score of 16 or more to qualify for further treatment
What is the initial management of urticaria caused by a drug/food/allergen?
Stop the offending drug/food/allergen
What is the initial management of urticaria caused by infection?
Treat infection
What is the initial management of urticaria caused by symptomatic dermographism?
Wear loose clothing
What is the initial management of urticaria caused by cold contact urticaria?
Dress warmly, avoid cold water and ice
What is the initial management of urticaria caused by delayed pressure urticaria?
Use something with narrow contact area instead of broad contact area
What is the initial management of urticaria caused by solar urticaria?
Sunscreen
What 4 types of drugs should be avoided when treating urticaria?
NSAIDs
Codeine
Aspirin
Certain antibiotics
What kind of antihistamine drug is used to treat urticaria, and how often per day?
Second generation H1 antihistamine up to QDS (4 times a day)
e.g. fexofenadine, cetirizine, loratadine
If taking second generation H1 antihistamine hasn’t treated urticaria, what drugs can be added?
Montelukast 10 mg daily
Cooling moisturisers e.g. menthol in aqueous cream
What medication is prescribed to treat urticaria flare ups?
Prednisolone 30 mg for 3-5 days
When combined antihistamine and montelukast is ineffective in treating urticaria, what drug is used next?
Anti IgE: Omalizumab injection
What drug can be added to omalizumab injections to make them more effective in treating urticaria?
Cyclosporin
Give 5 examples of DMARDs that can be prescribed to treat urticaria?
Cyclosporin
Azathioprine
Mycophenolate mofetil
Dapsone
Hydroxychloroquine
What kind of phototherapy can be used to treat urticaria?
UVB phototherapy
Which body areas are most affected by angioedema?
Face: Eyes, lips, mouth, tongue
Hands
Feet
Genitals
