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Dermatology Diploma > Urticaria > Flashcards

Urticaria Flashcards

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1
Q

What is urticaria?

A

Urticaria is a disease characterised by the development of wheals (also known as hives), angioedema or both.

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2
Q

What gender is more likely to get angioedema?

A

Women

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3
Q

What % of the population get urticaria?

A

20%

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4
Q

What are the 3 features of wheels?

A
  • Pink or white raised areas of skin of variable size that resemble nettle stings
  • They are usually itchy
  • They have a fleeting nature with the skin returning to its normal appearance within 24 hours although the condition itself may last longer
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5
Q

What takes longer to resolve: angioedema or urticaria?

A

Angiooedema - it can take up to 72 hours to resolve.

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6
Q

What % of patients with urticaria will also get angioedema?

A

30%

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7
Q

What is the pathophysiology of urticaria?

A
  • Degranulation of mast cell -> histamine & platelet activating factor release. -> Pruritus and vasodilation and increased permeability (leakiness) of blood vessels causing swelling and redness of the skin.
  • Cutaneous nerves stimulation may release neuropeptides, either directly onto the blood vessel or via the mast cell, which can generate the wheal and flare urticated response.
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8
Q

Describe the Triple Response of Lewis.

A
  1. Red spot: due to capillary dilatation
  2. Flare: redness in the surrounding area due to arteriolar dilatation mediated by axon reflex
  3. Wheal: due to exudation of fluid from capillaries and venules
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9
Q

What are the 3 types of Urticaria?

A
  1. Acute spontaneous urticaria (ASU) < 6 weeks.
  2. Chronic spontaneous urticaria (CSU) > 6 weeks.
  3. Physical Urticaria
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10
Q

Aprt form length of time, what is the difference between ASU and CSU?

A

ASU usually has a trigger - Drugs, Antibiotics or Food.

CSU usually has no trigger.

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11
Q

What physical reactions occur in ASU and CSU?

A

Spontaneous wheels +/- angioedema.

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12
Q

In what age group does CSU occur in?

A

20-30 years.

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13
Q

What test can you do in ASU (acute spontaneous urticaria)?

A

RAST test or a Skin Prick Test

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14
Q

What are subtypes of physical urticaria?

A
  • Dermographism
  • Delayed Pressure urticaria
  • Cholinergic urticaria
  • Cold induced urticaria
  • Solar urticaria
  • Aquagenic urticaria
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15
Q

What is the main management for physical urticaria?

A

Avoid the physical trigger

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16
Q

Tell me about Dermographism

A
  • 10% of population have it.
  • Wheal lasts 30-60 mins.
  • Symptomatic dermographism/factitious urticaria - severe cases of dermographism.
17
Q

Tell me about delayed pressure urticaria

A
  • Due to prolonged pressure to the skin.
    • Clapping - causes the hands to swell
    • Prolonged kissing - lips can swell.
      *
18
Q

Describe cholinergic urticaria.

A
  • Micropapular urticaria that occursover the body after sweating.
  • Not actually caused by acetylcholine but by neuropeptides released from nerve endings.
19
Q

Describe cold urticaria

A
  • Urticarial response after cold response.
  • To diagnose:
    • Put ice cube on skin
    • The urticarial response will occur on Re-Warming the skin.
20
Q

Describe solar urticaria

A
  • Very rare
  • Needs to be differentiated from polymorphic light eruption.
  • Response is immediate.
  • Light form the sun causes antigenic changes to proteins which mast cells then respond to by releasing histamine.
21
Q

Describe Contact Urticaria

A
  • Very common
  • Usually due to contact with a foreign agent.
22
Q

Describe the history taking

A
  • Ask about the history of urticaria - where on the body, how long.
  • Dietary history and correlation with food
  • Medication history
  • Allergy
  • FH of atopy and urticaria
  • Any concomitant medical history (e.g. bullous pemphigoid, SLE etc)
  • Determine if angioedema+/- bronchospasm
  • Recent infection or foreign travel.
23
Q

In urticaria, what investigations should be done?

A
  • Often no further invetigation is needed.
  • Allergy avoidance
  • RAST test or prick test can be organised.
  • If CSU - no investigations are needed.
24
Q

What conditions can mimic Chronic Spontaneous Urticaria (CSU)?

A
  • SLE and other connective tissue diseases
  • Bullous Pemphigoid and other immuno-bullous disorders
  • Atopic eczema / pompholyx
  • Thyroid dysfunction
  • Contact dermatitis
  • H.pylori gastritis
  • Toxic erythema (especially drug reactions)
  • Erythema multiforme
  • Viral exanthema such as measles
25
Q

Describe the Urticaria Activity Score (UAS)

A
26
Q

What is the treatment for Urticaria?

A
  • Antihistamines
    • 1st line - Cetirizine, Loratidine and Fexofenadine
    • 2nd line - Increase up to 4 times the recommended dose.
    • Use antihistamines continously at a low dose rather than PRN.
    • Can take 4 weeks to work.
    • Reduce doses every 3-6 months.
  • Steroids
    • Short courses of 20-50mg/day for 7-10 days.
  • Monteleukast - 3rd line.
  • Further therapy:
    • Ciclosporin - moderate direct effect on mast cells. Effective when used in combination with 2nd generation antihistamines.
    • Omalizumab - 400mg every 4 weeks - useful if antihistamines aren’t working.
    • Dapsone and H2-recetpor antagonists (e.g. ranitidine) - low evidence - consider as 3rd line.
27
Q

Describe the hereditary causes of angioedema without urticaria

A
  • C1-Esterase Inhibitor Deficiency - C1-INH-HAE.
  • Normal C1-Esterase Inhibitor
    • FXII mutation = Hereditary angioedema w FXII mutations - FXII-HAE.
    • Uknown cause - Hereditary Angioedema of unknown origin - U-HAE.
28
Q

Describe the causes of Acquired Angioedema without wheals.

A
  • No cause identified
    • Idiopathic histaminergic - IH-AAE.- Response to antihistamines -
    • Idiopathic non-histaminergic - InH-AAE - No response to antihistamines -
  • Acquired angioedema related to ACE-I - ACEI-AAE. - Caused by ACE-I Treatment.
  • Acquired angioedema with C1-INH deficiency - C1-INH-AAE. - C1-INH Deficiency with no family history.
29
Q

What is the most common cause of Hereditary angioedema?

A

Defect with the enzyme C1 esterase inhibitor (C1-INH)

  • Usually a family history.
  • Can also develop stomach cramps - due to angioedema of the guts
30
Q

What is the invetigation for hereditary angioedema (HAE)?

A
  • Measure C1-INH levels and function.
  • C4 levels are also usually low.
31
Q

What is the difference between Type 1 and Type 2 Hereditary angioedema (HAE)?

A
  • Type 1 disease - low levels of C1-INH.
  • Type 2 disease - poorly functioning.

(Note: Some patients will have a defect in the Factor XII gene)

32
Q

What is the treatment for Hereditary Angioedema (HAE)?

A
  • Emergency setting
    • Adrenaline and resuscitation.
    • Fresh frozen plasma or C1 esterase inhibitor concrete.
    • Many patients will have their own concrete in their fridge for emergency situations.
  • Long term management
    • Need a Medic Alert Bracelet.
    • Close access to C1 Esterase Inhibitor Concrete.
    • Anabolic steroids - Danazol or Stanozol.
33
Q

What is urticarial vasculitis?

A
  • Urticated rash with wheals, flare and itching.
  • Lesions last >24 hours.
  • They may resolve with purpura or bruising.
  • Systemic symptoms: joint pain, fever, abdominal pain and photosensitivity.
  • Associated with Connective Tissue Disease.
34
Q

How is urticarial vasculitis classified?

A
  • Normocomplementaemic
  • Hypocomplementaemic - Connective Tissue Disease and Systemic Symptolms are most common in this.
35
Q

How is the diagnosis of urticarial vasculitis made?

A

With a skin biopsy.

36
Q

What is the treatment for urticarial vasculitis?

A
  • Anti-histamines
  • NSAIDs
  • Recalcitrant disease - Dapsone, Colchicine, Hydroxychloroquine or a course of oral steroids.
37
Q

What is a mastocytoma?

A
  • A congregation of small individual lesions of mastocytes.
  • They urticate on rubbing (Darier’s sign)
  • Usually occur in children.
  • No pathological significance.
38
Q

What is Urticaria pigmentosa?

A
  • Widespread reddish brown macules
  • Urticate on rubbing (Darier’s sign).
  • Gradually resolve with time but will leave areas of hyperpigmentation
  • Treatment: antihistamines and sometimes PUVA. Ketotifen is sometimes used.

Dermatology Diploma (39 decks)

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