Urticaria & itch

Question 1

Define what urticaria is

Answer 1

A transient (lasting <24hrs) eruption of erythematous & oedematous swellings of the dermis (only skin), usually associated with itching

Question 2

Define what angioedema is

Answer 2

This is transient (24-48hrs) swellings in the deeper dermal, S/C & submucosal tissues (skin & mucous membranes)

Question 3

What are the 2 main types of urticaria ?

Answer 3

1. Acute = present < 6 weeks
2. Chronic = daily or episodic wheals or angioedema for > 6weeks

Question 4

Which is more common acute or chronic urticaria ?

Answer 4

• Acute - upto 30% of people will experience it
• Whereas chronic will only be experienced by upto 2% of people

Question 5

What parts of the body may be affected by angioedema ?

Answer 5

• All parts of the body (skin & mucous membranes) most often it is the eyes & lips
• In severe cases the internal lining of the URT & intestines may be affected

Question 6

What parts of the body may be affected by urticaria ?

Answer 6

Only the skin

Question 7

What are the clinical features of angioedema ?

Answer 7

• Marked swelling often around the mouth & eyes (throat, tongue, hands, feet &/or genitals may be affected too)
• Swellings occur below the surface of the skin & may be red (erythematous) or skin coloured
• Swellings may or may not be itchy, but are often painful & tender
• Swellings tend to be more localised

Question 8

What are the clinical features of urticaria ?

Answer 8

• Red patches & weals on the surface of the skin
• Usually very itchy & may have a burning sensation
• Pain & tenderness uncommon
• Can affect any skin site & tends to be distributed widely, weals shape is variable - may be round, form rings, map-like, target like lesion or form giant patches

Question 9

Describe what a weal is

Answer 9

This is a superficial skin coloured or pale swelling, surrounded by erythema

Question 10

What is shown in the pic ?

Answer 10

Angioedema

Question 11

What is shown in the pic ?

Answer 11

Urticaria - pic demonstrates the variable shape

Question 12

What is the difference between urticaria & angioedema ?

Answer 12

Angioedema & urticaria are very similar in many ways & can co-exist/overlap. The main differences are outlined in the table

Question 13

What is the underlying cause of urticaria & angioedema ?

Answer 13

• Result from release of chemical mediators from mast cells & basophils. For urticaria it is regulated by histamine, platelet-activating factor & cytokines whereas bradykinin mediares angioedema.
• The mediators activate sensory nerves, cause dilatation of blood vessels & leakage of fluid into surrounding tissues

Question 14

List the causes of urticaria & angioedema

Answer 14

• Allergy (type 1 IgE mediated)
• Direct chemical effects e.g. salicylates (e.g. aspirin), & other drugs
• Physcial - dermographism (from stroking), delayed pressure, virbation, aquagenic (after contact with water), solar (sun), cold & cholingeric
• Autoimmune diseases - e.g. SLE, thyroid, coeliacs
• Infections
• Idiopathic

Angioedema is the above causes + inherited or aquired C1 esterase inhibtor def. or ACE inhibitors

Question 15

How is angioedema or urticaria diagnosed ?

Answer 15

Clinically

Question 16

What is the treatment of angioedema or urticaria ?

Answer 16

If underlying cause identified then treat that

If no identifiable cause or seeing them acutely with symptoms treatment focuses on suppression of episode:

• 1st line = 2nd gen. anti-histamines for upto 6 weeks +/- if severe add oral corticosteroid for 7 days
• 2nd line = alternative 2nd gen. anti-histamine
• 3rd line = Leukotriene antagonist, sertonin antagnosits etc may be tried

Note - for angioedema if airways compromise this takes priority

Question 17

List the main different 2nd gen. anti-histamines

Answer 17

• Certirizine
• Loratidine
• Fexofenadine