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Dermatology Diploma > Urticaria > Flashcards

Flashcards in Urticaria Deck (38)
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1

What is urticaria?

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

2

What gender is more likely to get angioedema?

Women

3

What % of the population get urticaria?

20%

4

What are the 3 features of wheels?

  • 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

5

What takes longer to resolve: angioedema or urticaria?

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

6

What % of patients with urticaria will also get angioedema?

30%

7

What is the pathophysiology of urticaria?

  • 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

8

Describe the Triple Response of Lewis.

  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

9

What are the 3 types of Urticaria?

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

10

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

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

CSU usually has no trigger.

11

What physical reactions occur in ASU and CSU?

Spontaneous wheels +/- angioedema.

12

In what age group does CSU occur in?

20-30 years.

13

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

RAST test or a Skin Prick Test

14

What are subtypes of physical urticaria?

  • Dermographism
  • Delayed Pressure urticaria
  • Cholinergic urticaria
  • Cold induced urticaria
  • Solar urticaria
  • Aquagenic urticaria

15

What is the main management for physical urticaria?

Avoid the physical trigger

16

Tell me about Dermographism

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

17

Tell me about delayed pressure urticaria

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

18

Describe cholinergic urticaria.

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

19

Describe cold urticaria

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

20

Describe solar urticaria

  • 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

Describe Contact Urticaria

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

22

Describe the history taking

  • 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

In urticaria, what investigations should be done?

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

24

What conditions can mimic Chronic Spontaneous Urticaria (CSU)?

  • 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

Describe the Urticaria Activity Score (UAS)

26

What is the treatment for Urticaria?

  • 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

Describe the hereditary causes of angioedema without urticaria

  • 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

Describe the causes of Acquired Angioedema without wheals.

  • No cause identified
    • Idiopathic histaminergic - IH-AAE.Response to antihistamines -
    • Idiopathic non-histaminergic - InH-AAENo 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

What is the most common cause of Hereditary angioedema?

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

What is the invetigation for hereditary angioedema (HAE)?

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