Urticaria Flashcards

Dermatology

1
Q

Define urticaria (hives)?

A

Inflammatory skin condition characterised by wheals

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2
Q

What condition usually occurs with urticaria and why?

A

Angioedema

Both have same immune process

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3
Q

Define angioedema?

A

Swelling in subcutaneous tissue (under skin) that lasts up to 3 days

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4
Q

Is urticaria equally common in all ages?

A

No, less common in children than adults

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5
Q

Does everyone develop urticaria during their lifetime?

A

No, up to 20% individuals will develop urticaria once in their lifetime

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6
Q

What cell type causes the pathophysiology of urticaria?

A

Mast cells

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7
Q

How is mast cell degranulation triggered, in the pathophysiology of urticaria?

A

Autoantibodies/allergens bind to high affinity IgE receptors on mast cells or basophils, or bind to IgE that is already bound to receptor

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8
Q

What 6 substances are released from mast cell granules, in the pathophysiology of urticaria?

A

Histamines

Proteases

Platelet activating factor

Leukotriene C4

Prostaglandin D2

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9
Q

How does mast cell degranulation cause urticaria symptoms?

A

Causes plasma leakage from capillaries, which causes swelling and itching

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10
Q

Does urticaria always occur due to the same immune mechanism?

A

No, can result from different immune mechanisms that have similar presentations

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11
Q

Give 2 examples of immune mechanisms that can cause urticaria?

A

Type 1 immediate hypersensitivity due to an allergen, which is tested for with skin-prick testing

Type V stimulatory hypersensitivity due to an autoantibody

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12
Q

What is the main difference between acute and chronic urticaria?

A

Acute urticaria lasts less than 6 weeks

Chronic urticaria lasts more than 6 weeks

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13
Q

Give 7 known causes of acute urticaria?

A

Food

Medications (NSAIDs, aspirin, codeine)

Insect stings and bites

Viral or bacterial infection

Contact allergy to latex

Transfusion

Vaccination or idiopathic

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14
Q

Does acute urticaria always have a known cause?

A

No, can be idiopathic

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15
Q

What is the most dangerous complication of severe acute urticaria?

A

Can progress to anaphylactic shock

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16
Q

What is the difference between chronic inducible urticaria and chronic spontaneous urticaria?

A

Inducible: Has known trigger

Spontaneous: Has unknown trigger (idiopathic)

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17
Q

Give 5 conditions that can cause chronic inducible urticaria?

A

Autoimmune conditions eg. urticarial vasculitis

Autoantibodies

Neoplastic

Urticaria pigmentosa

Idiopathic

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18
Q

What type of urticaria is caused by lightly scratching skin?

A

Symptomatic dermographism: lightly scratching patient’s skin causes raised, inflamed lines or welts that tend to go away in less than 30 minutes

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19
Q

What type of urticaria is caused by sunlight?

A

Solar urticaria

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20
Q

What type of urticaria is caused by cold air, water or ice?

A

Cold contact urticaria

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21
Q

What type of urticaria is caused by heat?

A

Heat contact urticaria

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22
Q

What type of urticaria is caused by sweating?

A

Cholinergic urticaria

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23
Q

What type of urticaria is caused by pressure?

A

Delayed pressure urticaria

24
Q

What type of urticaria is caused by contact with chemicals?

A

Contact urticaria

25
Q

What type of urticaria is caused by water?

A

Aquagenic urticaria

26
Q

What type of urticaria is caused by vibrations?

A

Vibratory urticaria

27
Q

Give 3 causes of why angioedema can present without urticaria?

A

ACE inhibitor-induced angioedema

Hereditary angioedema (also known as C1 esterase inhibitor deficiency)

Acquired angioedema (which is complement C1q deficiency)

28
Q

In urticaria presentation, does only one type tend to present?

A

Different types of urticaria often present together

29
Q

Describe the typical appearance of wheals, in urticaria?

A

Superficial non-scaly plaques/swelling that are red or skin-coloured with clear edges

30
Q

Do wheals always have pale colour and clear edges, in urticaria?

A

No, can be dark red with annular (prominent) edges

31
Q

In urticaria, where do wheals tend to appear on body?

A

Anywhere

32
Q

How does wheals tend to present in chronic urticaria?

A

Faded, pink, flat wheals with no palpable swelling that are widespread

33
Q

How much time does it take for wheals to go down, in the usual presentation of urticaria, and do they leave any marks?

A

Less than 24 hours

Don’t leave marks, but if chronic there can be very faded marks

34
Q

How does contact urticaria usually present?

A

Wheals confined to the contact area, and occurs minutes after exposure

35
Q

When investigating urticaria, when would you do a skin biopsy?

A

Suspected urticarial vasculitis

36
Q

When investigating urticaria, when would you do a skin-pricking test?

A

Suspected allergen/irritant

37
Q

How do you use a TempTest to confirm cold or heat contact urticaria?

A

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

  1. Patient develops urticaria around areas that are 4-24 degrees celsius: Suggests cold urticaria
  2. Patient develops urticaria around areas that are 25-44 degrees celsius: Suggests heat urticaria
38
Q

How do you use dermographing to confirm systemic dermographism?

A

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

39
Q

How can you confirm cholinergic urticaria?

A

Asking patient to exercise and see if urticaria develops after sweating

40
Q

How can you confirm solar urticaria?

A

Phototesting

41
Q

What scoring tool can be used to measure severity of urticaria?

A

Urticaria Activity Score (UAS7): 7-day scoring tool for measurement of disease severity

42
Q

What UAS7 score is needed for a patient to qualify for omalizumab (anti-IgE antibody drug)?

A

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

43
Q

What is the initial management of urticaria caused by a drug/foo/allergen?

A

Stop the offending drug/food/allergen

44
Q

What is the initial management of urticaria caused by infection?

A

Treat infection

45
Q

What is the initial management of urticaria caused by symptomatic dermographism?

A

Wear loose clothing

46
Q

What is the initial management of urticaria caused by cold contact urticaria?

A

Dress warmly, avoid cold water and ice

47
Q

What is the initial management of urticaria caused by delayed pressure urticaria?

A

Use something with narrow contact area instead of broad contact area

48
Q

What is the initial management of urticaria caused by solar urticaria?

A

Sunscreen

49
Q

What 4 types of drugs should be avoided when treating urticaria?

A

NSAIDs

Codeine

Aspirin

Certain antibiotics

50
Q

What kind of antihistamine drug is used to treat urticaria, and how often per day?

A

Second generation H1 antihistamine up to QDS (4 times a day)

e.g. fexofenadine, cetirizine, loratadine

51
Q

If taking second generation H1 antihistamine hasn’t treated urticaria, what drugs can be added?

A

Montelukast 10 mg daily

Cooling moisturisers e.g. menthol in aqueous cream

52
Q

What medication is prescribed to treat urticaria flare ups?

A

Prednisolone 30 mg for 3-5 days

53
Q

When combined antihistamine and montelukast is ineffective in treating urticaria, what drug is used next?

A

Anti IgE: Omalizumab injection

54
Q

What drug can be added to omalizumab injections to make them more effective in treating urticaria?

A

Cyclosporin

55
Q

Give 5 examples of DMARDs that can be prescribed to treat urticaria?

A

Cyclosporin

Azathioprine

Mycophenolate mofetil

Dapsone

Hydroxychloroquine

56
Q

What kind of phototherapy can be used to treat urticaria?

A

UVB phototherapy

57
Q

Which body areas are most affected by angioedema?

A

Face: Eyes, lips, mouth, tongue

Hands

Feet

Genitals